Biology today may 2017 by mimimi945

Vol. XIX

No. 5

May 2017

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1. Heterosporous pteridophytes show certain characteristics, which are precursor to the â&#x20AC;&#x2DC;seed habitâ&#x20AC;&#x2122; in gymnosperms. One of such characteristics is (a) presence of vascular tissues (b) external water required for fertilisation (c) presence of embryo stage (d) development of embryo inside the female gametophyte. 2. The scientific name of Java man is (a) Homo habilis (b) Homo sapiens neanderthalensis (c) Homo erectus erectus (d) Australopithecus boisei. 3. Identify the incorrect statement regarding retrovirus? (a) Its DNA has no role in its life cycle. (b) There is a gene for RNA dependent DNA polymerase. (c) Genetic material is RNA. (d) None of these.

7. Unidirectional transmission of a nerve impulse through nerve fibre is due to the fact that (a) nerve fibre is insulated by a medullary sheath (b) sodium pump starts operating only at the cyton and then continues into the nerve fibre (c) neurotransmitters are released by dendrites and not by axon endings (d) neurotransmitters are released by the axon endings and not by dendrites. 8. Given below is a pedigree chart of a family with five children. It shows the inheritance of attached ear-lobes as opposed to the free ones. The squares represent the male individuals and circles, the female individuals. Which one of the following conclusions is correct?

4. Graft between individuals of different species is called (a) xenograft (b) isograft (c) autograft (d) allograft. 5. Taxonomic hierarchy refers to (a) stepwise arrangement of all categories for classification of plants and animals (b) a group of senior taxonomists who decide the nomenclature of plants and animals (c) a list of characteristics of organisms ranging from less important to most important for taxonomic purposes (d) classification of a species based on fossil record. 6 . In which one of the following, the genus name, its two characters and its phylum are not correctly matched? Genus name Characters Phylum (a) Pila (i) Body segmented Mollusca (ii) Mouth with radula (b) Asterias (i) Spiny skinned Echinodermata (ii) Water vascular system (c) Sycon (i) Pore bearing Porifera (ii) Canal system (d) Periplaneta (i) Jointed appendages Arthropoda (ii) Chitinous exoskeleton 8

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Attached Ear - lobe Free Ear - lobe

(a) (b) (c) (d)

Key : Male Female

The parents are homozygous recessive. The trait is Y-linked. The parents are homozygous dominant. The parents are heterozygous.

9. In mammals, the opening of inferior vena cava in the right auricle is guarded by (a) Mitral valve (b) Eustachian valve (c) tricuspid valve (d) Thebasian valve. 10. Which type of ecosystem will be present in a place if there is an annual rainfall of over 250 cm? (a) Tropical forests (b) Grasslands (c) Deciduous forests (d) Temperate forests 11 . Study the given statements about gymnosperms and select the correct option. (i) Mode of fertilisation is siphonogamy. (ii) Male and female cones are borne on same tree in Pinus.

(iii) (a) (b) (c) (d)

Endosperm represents female gametophyte. Statements (i) and (ii) are correct Statements (ii) and (iii) are correct Statements (i) and (iii) are correct Statements (i), (ii) and (iii) are correct

12. Excitation of chlorophyll molecule due to light is a (a) photo-oxidation reaction (b) endergonic reaction (c) thermochemical reaction (d) photochemical reaction. 13. Frameshift mutation occurs when (a) base is substituted (b) base is deleted or added (c) anticodons are absent (d) none of these. 14. Which one of the following categories of animals, is correctly described with no single exception in it? (a) All reptiles possess scales, have a three chambered heart and are cold blooded (poikilothermal). (b) All bony fishes have four pairs of gills and an operculum on each side. (c) All sponges are marine and have collared cells. (d) All mammals are viviparous and possess diaphragm for breathing. 15. Mendel was not able to say anything about recombination and crossing over because (a) he did not have a large and strong microscope (b) he choose only contrasting characters (c) traits he choose, were not linked and present on different chromosomes or were far apart (d) traits he choose had no genes. 16. Select the mismatched pair out of the following. (a) Rhizome – Dryopteris, Nelumbo nucifera (b) Corm – Crocus sativus, Amorphophallus (c) Sucker – Curcuma domestica, Zingiber officinale (d) Tuber – Helianthus tuberosus, Solanum tuberosum 17. Which one of the following four secretions is correctly matched with its source, target and nature of action? Secretion (a) Gastrin

Target Action Oxyntic cells Production of HCl (b) Inhibin HypothInhibition of alamus secretion of gonadotropin releasing hormone (c) Enterokinase Duodenum Gall bladder Release of bile juice (d) Atrial Cardiocytes of JuxtaInhibition of Natriuretic atria glomerular release of renin Factor apparatus (ANF) (JGA)

Source Stomach lining Sertoli cells

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18. Pollen grains are well preserved as fossils because of the presence of (a) sporopollenin (b) lignin (c) suberin (d) pectin. 19. Which of the following is incorrect statement about the plasmids ? (a) It is the extra chromosomal DNA in bacteria. (b) It is not an integral part but inert genetic material. (c) Host chromosome can be integrated with the plasmid. (d) Transfer of plasmid can be done from one cell to another without killing the host. 20. Cu ions released from copper-releasing intrauterine devices (IUDs) (a) make uterus unsuitable for implantation (b) decrease phagocytosis of sperms (c) suppress sperm motility (d) prevent ovulation. 21. What is the source of Ti plasmid which is used as a cloning vector to deliver the desirable genes into plant cells? (a) Agrobacterium tumefaciens (b) Thermophilus aquaticus (c) Pyrococcus furiosus (d) Aedes aegypti A 22. In a condensed schematic RuBP Unstable compound representation of dark PGA reaction of photosynthesis B given below, steps are indicated by alphabets. RuMP C 1, 3 Di PGA Select the option where the D 3 PGA alphabets are correctly Glucose identified. (a) A-CO2 fixation, B-Reduction, C-Phosphorylation, D-Regeneration (b) A-Regeneration, B-CO2 fixation, C-Reduction, D-Phosphorylation (c) A-CO2 fixation, B-Phosphorylation, C-Reduction, D-Regeneration (d) A-CO2 fixation, B-Phosphorylation, C-Regeneration, D-Reduction 23. Specimen A is an example of symbiotic association between B and C. Both B and C have cell wall, B lacks photosynthetic ability while C is capable of it. Identify A, B and C. A B C (a) Lichen Algae Fungi (b) Lichen Fungi Algae (c) Lichen Bacteria Algae (d) Mycorrhiza Fungi Algae 24. Thermococcus, Methanococcus and Methanobacterium exemplify (a) bacteria whose DNA is relaxed or positively supercoiled but which have a cytoskeleton as well as mitochondria (b) bacteria that contain a cytoskeleton and ribosomes

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(c) archaebacteria that contain a monolayer of branched chain lipids in the cell membrane. (d) archaebacteria that possess histones resembling those found in eukaryotes but whose DNA is negatively supercoiled. 25. Which one is correct sequence of urine formation? (a) Secretion, reabsorption, filtration (b) Filtration, reabsorption, secretion (c) Reabsorption, filtration, secretion (d) Reabsorption, secretion, filtration

33. Biolistic technique is used in (a) tissue culture (b) gene transfer (c) hybridisation process (d) germplasm conservation. 34. Study the given flow chart and identify A and B. Atmospheric N2 Biological Industrial Electrical N2 fixation N2 fixation N2 fixation A

26. Ulothrix can be described as a (a) filamentous alga lacking flagellated reproductive stages (b) membranous alga producing zoospores (c) filamentous alga with flagellated reproductive stages (d) non-motile colonial alga lacking zoospores.

NH3

30. If in a population, natality is balanced by mortality then there will be (a) decrease in population growth (b) zero population growth (c) increase in population growth (d) over population. 31. Which of the following is not an effect of the sympathetic nervous system? (a) Dilation of pupil (b) Reduction of peristalsis (c) Elevation of blood pressure (d) Stimulation for saliva secretion 32. Mammalian lungs have an enormous number of minute alveoli (air sacs). This is to allow (a) more surface area for diffusion of gases (b) more space for increasing the volume of inspired air (c) more nerve supply to keep the lungs working (d) more spongy texture for keeping lung in proper shape. 12

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NO3– Uptake

27. Non-cellular layer that connects inner surface of the epithelial tissue to the connective tissue is (a) basement membrane (b) epidermis (c) dermis (d) either (b) or (c). 28. Antigen binding site in an antibody is found between (a) two light chains (b) two heavy chains (c) one heavy and one light chain (d) either between two light chains or between one heavy and one light chain depending upon the nature of antigen. 29. In double fertilisation (a) two male gametes fuse with two eggs (b) one male gamete fuses with the egg and the other fuses with the secondary nucleus (c) one male gamete fuses with the egg and the other fuses with the antipodal (d) one male gamete fuses with the antipodal and the other fuses with the diploid nucleus.

NO2– Soil

Decaying biomass

Plant biomass

Animal biomass

(a) (b) (c) (d)

A Mineralisation Ammonification Denitrification Denitrification

B Demineralisation Denitrification Ammonification Mineralisation

35. Populations are said to be sympatric when (a) two populations live together and freely interbreed to produce sterile offspring (b) two populations are physically isolated by natural barriers (c) two populations are isolated but occasionally come together to interbreed (d) two populations share the same environment but cannot interbreed. 36. The conidiophores of Pencillium are (a) uninucleate and colourless (b) uninucleate and pigmented (c) nucleate and colourless (d) anucleate and pigmented. 37. The flower shown in the following diagram is

(a) (b) (c) (d)

homochlamydeous, unisexual and hypogynous homochlamydeous, bisexual and epigynous dichlamydeous, bisexual and hypogynous heterochlamydeous, bisexual and epigynous.

38. Based on cellular mechanisms there are two major types of regeneration found in the animals. Which one of the following is the correct example of the type mentioned? (a) Morphallaxis – Regeneration of two transversely cut equal pieces of a Hydra into two small Hydra. (b) Epimorphosis – Replacement of old and dead erythrocytes by the new ones (c) Morphallaxis – Healing up of a wound in the skin (d) Epimorphosis – Regeneration of crushed and filtered out pieces of a Planaria into as many new planarians 39. Which of the following statements is correct regarding short day plants (SDPs)? (a) They can flower in complete darkness if supplied with exogenous nutrients. (b) They are the same as long day plants. (c) They do not have a critical photoperiod. (d) All of these 40. Severe Acute Respiratory Syndrome (SARS) (a) is caused by Pneumococcus pneumoniae (b) is caused by a corona virus (c) is an acute form of asthma (d) is characterised by replacement of lung tissue by fibrous connective tissue. 41. Myxomycetes are (a) saprobes or parasites, having mycelia, asexual reproduction by fragmentation, sexual reproduction by fusion of gametes (b) slimy mass of multinucleate protoplasm, having pseudopodia-like structures for engulfing food, reproduction through fragmentation or zoospores (c) prokaryotic organisms, cellular or acellular, saprobic or autotrophic, reproduce by binary fission (d) eukaryotic, single-celled or filamentous, saprobic or autotrophic, asexual reproduction by fusion of two cells or their nuclei. 42. Select the correct explanation for the labels A, B, C and D. A

B C D

(a) A represents the fertilised zygote. (b) B represents the stage of morula formation.

(c) C represents the blastocyst. (d) D represents the blastocyst implantation. 43. Which one of the following statement pertaining to pollutants is correct? (a) DDT is a non-biodegradable pollutant. (b) Excess fluoride in drinking water causes osteoporosis. (c) Excess cadmium in drinking water causes black foot disease. (d) Methylmercury in water may cause itai itai disease. 44. In the prothallus of a vascular cryptogam, the antherozoids and eggs mature at different times. As a result (a) there is high degree of sterility (b) one can conclude that the plant is apomictic (c) self fertilisation is prevented (d) there is no change in success rate of fertilisation. 45. Stink gland is found in (a) 4th and 5th terga of cockroach (b) 5th and 6th terga of cockroach (c) 5th and 6th sterna of cockroach (d) 4th and 5th sterna of cockroach. 46. A pome fruit is said to be false because (a) the pericarp is inconspicuous (b) the endocarp is prominent (c) the fruit is present in fleshy edible thalamus (d) the pericarp is divided into epicarp, mesocarp and endocarp. 47. In India, we find mangoes with different flavours, colours, fibre content, sugar content and even shelf-life. The large variation is on account of (a) species diversity (b) induced mutations (c) genetic diversity (d) hybridisation. 48. In which one of the following sets of three items each belong to the category mentioned against them? (a) Lysine, glycine, thiamine –– amino acids (b) Myosin, oxytocin and gastrin –– hormones (c) Rennin, helicase and hyaluronidase –– enzymes (d) Optic nerve, oculomotor, vagus –– sensory nerves 49. Which one of the following statements pertaining to plant structure is correct? (a) Cork lacks stomata, but lenticels carry out transpiration. (b) Passage cells help in transfer of food from cortex to phloem. (c) Sieve tube elements possess cytoplasm but no nuclei. (d) The shoot apical meristem has a quiescent centre. 50. In the development of the human body, the ectoderm is responsible for the formation of (a) sweat glands (b) lens of the eye (c) nervous system (d) all of these. MT BIOLOGY

TODAY | MAY ‘17

51. Match column I with column II and choose the correct option. Column I Column II (Scientist) (Concept) I. Meselson and Stahl A. Lac operon II. Hershey and Chase B. DNA replicates semi-conservatively III. Beadle and Tatum C. One gene one enzyme hypothesis IV. Jacob and Monod D. DNA is the genetic material E. Transcription (a) I - B, II - E, III - A, IV - C (b) I - C, II - D, III - B, IV - A (c) I - B, II - D, III - C, IV - A (d) I - A, II - E, III - D, IV - B 52. DNA finger printing technique was first developed by (a) Jeffreys, Wilson and Thien (b) Boysen and Jensen (c) Schleiden and Schwann (d) Edward and Steptoe. 53. Choose the correct pair. (a) Coconut, Cucurbits - dioecious (b) Honey bee, Rotifers - parthenogenesis (c) Ornithorhynchus, Whale - viviparous (d) Frog, Peacock - external fertilisation 54. Which one of the following correctly describes homologous structures ? (a) Organs with anatomical similarities, but performing different functions (b) Organs with anatomical dissimilarities, but perform same function (c) Organs that have reduced or do not perform any function (d) Organs that appear only in embryonic stage and disappear later in the adult 55. Retting is a process by which bacteria bring about (a) curdling of milk (b) separation of fibres (c) synthesis of various vitamins (d) both (a) and (c). 56. Select the group of the three codons which could bring a halt in protein synthesis. (a) UGG, UCG, UAU (b) UUC, UUA, UAC (c) UAG, UGA, UAA (d) UUG, UCA, UCG 57. Select the correct pair of microorganism and the product obtained from it. (a) Monascus purpureus - produces large holes in Swiss cheese (b) Saccharomyces cerevisiae - used for the distillation of wine and beer 14

MT BIOLOGY

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(c) Streptococcus - produces streptokinase which is used to remove clots (d) Aspergillus niger - produces citric acid and butyric acid 58. Fats absorbed into lacteals as chylomicrons are (a) monoglycerides (b) fatty acids (c) triglycerides (d) glycerol. 59. Which of the following disorders are caused due to recessive autosomal mutations? (a) Turner’s syndrome and sickle cell anaemia (b) Edward’s syndrome and Down’s syndrome (c) Cystic fibrosis and phenylketonuria (d) Alzheimer’s disease and Huntington’s chorea 60. Which one of the following has incorrect description? (a) Lubb - sharp closure of AV valves at the beginning of ventricular systole (b) Dup - sudden opening of semilunar valves at the beginning of ventricular diastole (c) Pulsation of the radial artery - valves in the blood vessels (d) Initiation of the heart beat - Purkinje fibres 61. An oocyte is released from the ovary under the influence of LH (a) before completing meiosis I and before polar bodies are released (b) after completing meiosis I (c) after completing meiosis II (d) before completing meiosis I and after release of polar bodies. 62. In most simple type of canal system of Porifera, water flows through which one of the following ways ? (a) Ostia → Spongocoel → Osculum → Exterior (b) Spongocoel → Ostia → Osculum → Exterior (c) Osculum → Spongocoel → Ostia → Exterior (d) Osculum → Ostia → Spongocoel → Exterior 63. The quiescent centre in root meristem serves as a (a) site for storage of food which is utilised during maturation (b) reservoir of growth hormones (c) reserve for replenishment of damaged cells of the meristem (d) region for absorption of water. 64. Which property among these listed below is not a criteria for a molecule to act as a genetic material? (a) Chemically and structurally stable (b) Mutate slowly to facilitate evolution (c) Express itself in the form of Mendelian characters (d) Destroy itself after every cell cycle 65. Which one of the following poultry birds is not an English breed ? (a) Sussex (b) Australorp (c) Orpington (d) Minorca

66. Match the source gland with its respective hormone and function and select the correct option. Source Hormone Function (a) Anterior pituitary Oxytocin Contraction of uterus muscles during child birth (b) Posterior pituitary Vasopressin Stimulates reabsorption of water in the distal tubules of the nephron (c) Corpus luteum Estrogen Supports pregnancy (d) Thyroid Thyroxine Regulates blood calcium level 67. In photorespiration, glycine moves from (a) chloroplast to peroxisome (b) peroxisome to mitochondrion (c) mitochondrion to peroxisome (d) chloroplast to mitochondrion. 68. Standing crops refers to (a) all the photosynthetic living forms in an area (b) all the living forms in an area (c) the amount of living matter present in a unit area of an ecosystem at any time (d) all the crop plants in an area. 69. In which population interaction one species is harmed whereas the other is unaffected? (a) Amensalism (b) Commensalism (c) Parasitism (d) All of these 70. If a homozygous dominant red-flowered plant is crossed with a homozygous recessive white-flowered plant, the offsprings will be (a) 50% white flowers (b) 50% red flowers (c) 100% white flowers (d) 100% red flowers. 71. Read the following statements and select the correct options. 1. Synaptic cleft of neurons secrete adrenaline. 2. Myelinated nerve fibres have Schwann cells which form a myelin sheath around the axon. 3. In non-myelinated nerve fibres Schwann cells do not form myelin sheath. 4. Spinal cord and cranial nerves are made of nonmyelinated nerve fibres. (a) 1, 2 and 3 are correct while 4 is incorrect (b) 3 and 4 are correct while 1 and 2 are incorrect (c) 1 and 4 are correct while 2 and 3 are incorrect (d) 2 and 3 are correct while 1 and 4 are incorrect. 72. The loss or excretion of water in the form of liquid droplets from the leaves and other parts of an uninjured or intact plant is called (a) guttation (b) transpiration (c) plasmolysis (d) translocation.

73. The order of blood flow from right ventricle to left ventricle in mammalian heart is (a) Right ventricle → pulmonary arteries → lungs → pulmonary veins → left atrium (b) Right ventricle → pulmonary veins → lungs → pulmonary arteries → left atrium (c) Right ventricle → right atrium → lungs → pulmonary veins → left atrium (d) Right ventricle → systemic aorta → lungs → pulmonary veins → left atrium. 74. Choose the correct statement. (a) Oxygen is vital in respiration to drive the process by removal of hydrogen. (b) Pyruvate is formed in the mitochondrial matrix. (c) There is complete oxidation of glucose in fermentation. (d) During the oxidation of succinic acid a molecule of ATP is synthesised. 75. The food chain, in which micro-organisms breakdown the energy rich compounds synthesised by the producers is called (a) grazing food chain (b) detritus food chain (c) parasitic food chain (d) predator food chain. 76. Find out the mismatched pair. (a) Primary CO2 fixation product of C4 plants (b) Primary CO2 acceptor of C3 plants (c) Calvin pathway of C4 plants occur in (d) C3 plant

→ OAA → RuBP → Bundle sheath → Maize

77. Myxoedema occurs due to (a) hypersecretion of thyroid hormone (b) hyposecretion of thyroid hormone (c) hypersecretion of parathormone (d) hyposecretion of parathormone. 78. Urea synthesis takes place primarily in liver because (a) NH3 and CO2 are present in liver only (b) hormone ADH is found in liver only (c) enzyme arginase is present in liver only (d) kidney is smaller than liver. 79. According to Central Pollution Control Board (CPCB), the size of particulate matter that is most harmful is (a) 25 mm (b) 2.5 mm (c) 0.25 mm (d) 0.025 mm. 80. Hotspots of biodiversity means (a) areas of the earth that contain many endemic species (b) species that serve as proxy for entire communities in particular area (c) species in particular niche/area (d) species diversity at particular area. MT BIOLOGY

TODAY | MAY ‘17

81. The hormone used in a suspension culture is (a) 2, 4-D (b) BAP (c) NAA (d) none of these.

86. Excess proteins, carbohydrates and fats are stored in body as (a) fat (b) glycogen (c) starch (d) ATP.

82. Match column I with column II and choose the correct option. Column I Column II (Types of joints) (Bones involved) A. Ball and socket 1. Carpal and metacarpal of thumb of hand B. Hinge 2. Atlas and axis C. Pivot 3. Frontal and parietal bone D. Saddle 4. Knee 5. Humerus and pectoral girdle (a) A – 5, B – 4, C – 2, D – 1 (b) A – 1, B – 3, C – 4, D – 5 (c) A – 5, B – 4, C – 3, D – 1 (d) A – 1, B – 2, C – 5, D – 4

87. What is true about Bt toxin? (a) Bt protein exists as active toxin in the Bacillus. (b) The activated toxin enters the ovaries of the pest to sterilise it and thus prevent its multiplication. (c) The concerned Bacillus has antitoxins. (d) The inactive protoxin gets converted into active form in the insect gut.

83. Which of the following is exhibited by C4 plants? A. Kranz anatomy B. The product of photosynthesis is oxaloacetic acid C. Both PEP carboxylase and Ribulose-bisphosphate carboxylase act as carboxylating enzymes (a) A and B only (b) B and C only (c) A and C only (d) A, B and C 84. Match the items of column I with column II and select the correct option. Column I Column II A. Electrostatic 1. Removes gases like SO2 precipitator B. Scrubber 2. Reduces automobile emission C. Catalytic converter 3. Removes particulate matter (a) A – 2, B – 3, C – 1 (b) A – 3, B – 2, C – 1 (c) A – 1, B – 2, C – 3 (d) A – 3, B – 1, C – 2 85. Match column I with column II and select the correct option from codes given below. Column I Column II A. Phosphoenol p. 6-carbon compound pyruvate (PEP) B. Ribulose q. 2-carbon compound biphosphate (RuBP) C. Oxaloacetic acid r. (OAA) D. Acetyl co-enzyme-A s. t. (a) A-t, B-s, C-r, D-q (b) (c) A-t, B-p, C-q, D-r (d) 16

MT BIOLOGY

88. Ozone depletion in stratosphere would result in increased (a) forest fires (b) global warming (c) skin cancer incidences (d) none of these. 89. Golden rice is a transgenic crop of the future with the following improved trait (a) insect resistance (b) high lysine (essential amino acid) content (c) high protein content (d) high vitamin A content. 90. Cell wall consists of (a) lignin, hemicellulose, tubulin and lipid (b) hemicellulose, cellulose, tubulin and lignin (c) lignin, hemicellulose, tubulin and lipid (d) lignin, hemicellulose, pectin and cellulose.

ANSWER 1. 6. 11. 16. 21. 26. 31. 36. 41. 46. 51. 56. 61. 66. 71. 76. 81. 86.

TODAY | MAY ‘17

2. 7. 12. 17. 22. 27. 32. 37. 42. 47. 52. 57. 62. 67. 72. 77. 82. 87.

3. 8. 13. 18. 23. 28. 33. 38. 43. 48. 53. 58. 63. 68. 73. 78. 83. 88.

ANSWERS

4-carbon compound 5-carbon compound 3-carbon compound A-r, B-s, C-t, D-p A-q, B-r, C-s, D-t

(d) (a) (d) (c) (a) (c) (d) (b) (b) (c) (c) (c) (b) (b) (d) (d) (a) (b)

1. 2. 3. 4.

Peroxisomes Nuclear matrix Typhoid Toxoid vaccine

(d) (d) (d) (a) (b) (c) (b) (a) (a) (c) (b) (c) (c) (c) (a) (c) (d) (c)

KEY 4. 9. 14. 19. 24. 29. 34. 39. 44. 49. 54. 59. 64. 69. 74. 79. 84. 89.

(a) (b) (b) (b) (c) (b) (c) (a) (c) (c) (a) (c) (d) (a) (a) (b) (d) (d)

5. 10. 15. 20. 25. 30. 35. 40. 45. 50. 55. 60. 65. 70. 75. 80. 85. 90.

(a) (a) (c) (c) (b) (b) (d) (b) (b) (d) (b) (a) (d) (d) (b) (a) (a) (d) 

WHO AM I ... Pg. Pg. Pg. Pg.

34 39 63 72

PRACTICE PAPER

AIIMS

1. According to Steward’s starch hydrolysis theory, which one of the following is the principle reason for the opening of stomata during daytime? (a) Influx of K+ ions into guard cells under the influence of ABA hormone. (b) Conversion of sugar into starch in guard cells. (c) Efflux of K+ ions from guard cells under the influence of ABA hormone. (d) Photosynthetic utilisation of CO2 in guard cells. 2. An insect bite may result in inflammation of that spot. This is triggered by chemicals such as (a) histamine and dopamine (b) histamine and kinins (c) interferon and opsonin (d) interferon and histone. 3. When a stimulus several times greater than the threshold stimulus is provided to a muscle fibre, it will (a) contract with a smaller force (b) contract with a larger force (c) contract with the same force (d) fail to contract.

4. Match column I with column II and choose the correct answer. Column I Column II A. Cleistogamy m. Insect pollination B. Geitonogamy n. Bud pollination C. Entomophily o. Pollination between flowers in the same plant D. Xenogamy p. Wind pollination q. Cross pollination (a) A-o; B-m; C-q; D-n (b) A-m; B-q; C-n; D-o (c) A-n; B-o; C-m; D-q (d) A-q; B-p; C-o; D-n 5. Evolutionary convergence is characterised by (a) development of dissimilar characteristics in closely related groups (b) development of a common set of characteristics in groups of different ancestry (c) development of characteristics by random mating (d) replacement of common characteristics in different groups.

Exam on 28th May

6. Apart from corticotropin releasing hormone (CRH), which other hormone also stimulates the release of adrenocorticotropic hormone (ACTH)? (a) Epinephrine (b) Aldosterone (c) Insulin (d) Vasopressin 7. The state, during which the respiratory centre is inhibited, is termed as (a) anoxia (b) asphyxia (c) suffocation (d) choking. 8. Which of the following option is incorrect with respect to electron transport system (ETS)? (a) It involves cytochrome–b, cytochrome–c, cytochrome–a, cytochrome–a3. (b) Each NADH2 gives 3 ATP (through ETS) and each FADH2 gives 2 ATP (through ETS). (c) There is a progressive increase in energy level of electron through ETS. (d) ETS reaction is a redox reaction. 9. Select the mismatched pair. (a) PCT - Absorption of hormones and vitamins (b) DCT - Absorption of glucose (c) Henle’s loop - Concentration of urine (d) Bowman’s capsule - Glomerular filtration 10. Study the given diagram and identify the cells labelled as A, B, C and D, and choose the correct option.

(a) (b) (c) (d)

A-Eosinophil, B-Erythrocyte, C-Neutrophil, D-Basophil A-Eosinophil, B-Lymphocyte, C-Neutrophil, D-Basophil A-Erythrocyte, B-Basophil, C-Neutrophil, D-Lymphocyte A-Eosinophil, B-Monocyte, C-Neutrophil, D-Lymphocyte MT BIOLOGY

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11. Which one of the following is a pair of endangered species? (a) Garden lizard and Mexican poppy (b) Rhesus monkey and sal tree (c) Clouded leopard and carrot grass (d) Hornbill and Indian aconite 12. Which one of the following is a correct statement? (a) “Bt” in “Bt-cotton” indicates that it is a genetically modified variety produced through biotechnology. (b) Somatic hybridisation involves fusion of two complete plant cells carrying desired genes. (c) The anticoagulant hirudin is being produced from transgenic Brassica napus seeds. (d) “Flavr savr” variety of tomato has enhanced the production of ethylene which improves its taste. 13. Select the correct statement given below which mentions the characteristics of monocot stem anatomy. (a) Hypodermis is sclerenchymatous, vascular bundles are closed, phloem parenchyma is present. (b) Hypodermis is sclerenchymatous, vascular bundles are closed, phloem parenchyma is absent. (c) Hypodermis is sclerenchymatous, vascular bundles are open, phloem parenchyma is absent. (d) Hypodermis is collenchymatous, vascular bundles are closed, phloem parenchyma is present. 14. The cell organelle involved in the glycosylation of proteins is (a) ribosome (b) peroxisome (c) mitochondrion (d) Golgi apparatus. 15. Conditioned reflexes are different than unconditioned reflexes in which of the following ways ? (a) Conditioned reflexes are limited to brain (b) Conditioned reflexes are inheritable (c) Unconditioned reflexes depend on previous experience (d) Unconditioned reflexes are limited to brain 16. How many NADPH and ATP are required for the production of one molecule of glucose in Calvin cycle? (a) 12 NADPH, 18 ATP (b) 18 NADPH, 12 ATP (c) 8 NADPH, 12 ATP (d) 2 NADPH, 3 ATP 17. Which one of the following is the most likely root cause of absence of menstruation in a human female having normal menstrual cycles? (a) Maintenance of the hypertrophical endometrial lining (b) Maintenance of high concentration of sex-hormones in the blood stream (c) Degeneration of corpus luteum (d) Low production of luteinising hormone 18. In mature human oocyte, which of the following parts contains acid mucopolysaccharides? (a) Cortical granules (b) Zona pellucida (c) Corona radiata (d) Perivitelline space 18

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19. Read the following statements and choose the correct option with respect to DNA. A. Nitrogenous base is linked to the pentose sugar through a N-glycosidic linkage. B. Phosphate group is linked to 5’-OH of a nucleoside through phosphoester linkage. C. Two nucleosides are linked through 3’ – 5’ N-glycosidic linkage. D. Negatively charged DNA is wrapped around positively charged histone octamer to form nucleosome. (a) A, B and C are wrong (b) D alone is wrong (c) C alone is wrong (d) A alone is wrong 20. Tissue culture technique can produce infinite number of new plants from a small parental tissue. The economic importance of the technique is in raising (a) genetically uniform population identical to the original parent (b) homozygous diploid plants (c) new species (d) hybrids of sexually reproducing plants. 21. Drinking of mineral water with very low level of pesticides (about 0.02 ppm) over a long period may (a) produce immunity against amoebic dysentery (b) cause rheumatoid arthritis in most people (c) cause Wernicke’s syndrome (d) lead to accumulation of pesticide residues in body. 22. Quarantine regulation are concerned with (a) spraying of diseased plants with insecticide (b) prevention of entry of diseased plants in country (c) growing or entry of diseased plants in country (d) hybrids of sexually reproducing plants. 23. Which one out of A – D given below correctly represents the structural formula of Lysine?

NH2

COOH

C COOH CH2

NH2 H

CH2

NH2

CH2

COOH

CH2

C O

CH2OH

CH2 NH2

(a) C (c) A

(b) D (d) B

24. Which of the following options correctly mentions mustard family and its characteristics? (a) Brassicaceae – tetramerous flowers, six stamens, bicarpellary gynoecium, siliqua type fruit (b) Brassicaceae – pentamerous flowers, many stamens, pentacarpellary gynoecium, capsule type fruit (c) Solanaceae - pentamerous flowers, five stamens, bicarpellary gynoecium, berry type fruit (d) Poaceae – trimerous flowers, three stamens, monocarpellary gynoecium, caryopsis type of fruit 25. In spermatogenesis, reduction division of chromosome occurs during conversion of (a) spermatogonia to primary spermatocytes (b) primary spermatocytes to secondary spermatocytes (c) secondary spermatocytes to spermatids (d) spermatids to sperms. 26. The major limiting factors of an animal population, food and space operate through which of the following determinants to bring about comparative stability of the population? (a) Natality (b) Immigration (c) Emigration and mortality (d) All of these 27. Which one is mismatched? (a) Hydra vulgaris - sea water (b) Hydra gangetica - fresh water (c) Obelia - sea water (d) Physalia - sea water 28. Chiasmata are most appropriately observed in meiosis during (a) diakinesis (b) diplotene (c) metaphase-II (d) pachytene. 29. Which of the following synthetic growth regulators is used to promote flowering in pineapple? (a) Indolebutyric acid (b) Phenylmercuric acetate (c) Benzyl aminopurine (d) 2-chloroethylphosphonic acid 30. A person saw a snake in his room when he opened the door. Which one of the following is likely to happen in his neuro-hormonal control system? (a) Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal medulla. (b) Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal cortex. (c) Hypothalamus activates the parasympathetic division of brain. (d) Neurotransmitters diffuse rapidly across the cleft and transmit a nerve impulse.

31. Keystone species deserve protection because these (a) are capable of surviving in harsh environmental conditions (b) indicate presence of certain minerals in the soil (c) have become rare due to overexploitation (d) play an important role in supporting other species. 32. The function of leghaemoglobin, during biological nitrogen fixation in root nodules of legumes, is to (a) convert atmospheric N2 to NH3 (b) convert ammonia to nitrite (c) transport oxygen for activity of nitrogenase (d) protect nitrogenase from oxygen. 33. Red snow is caused by which of the following in alpine vegetation? (a) Oscillatoria (b) Chlamydomonas (c) Batrachospermum (d) Sargassum 34. What will happen if the secretion of parietal cells of gastric glands is inhibited? (a) In the absence of HCl secretion, inactive pepsinogen is not converted into the active enzyme pepsin. (b) Gastric juice will be deficient in gastric amylase. (c) Enterokinase will not be released from the duodenal mucosa so, trypsinogen is not converted to trypsin. (d) Gastric juice will be deficient in pepsinogen. 35. A female delivers a baby suffering from stunted growth, mental retardation, low intelligence quotient and reduced metabolic rate. This is the result of (a) hyposecretion of growth hormone (b) hypersecretion of pituitrin (c) deficiency of iodine in diet (d) cancer of the adrenal gland. 36. A common characteristic for both bacterial and fungal cell wall structure is (a) it is made of cellulose (b) it has mucopeptide (c) it is made up of N-acetylglucosamine (d) it has lipid bilayer. 37. During an injury, nasal septum gets damaged and for its recovery the cartilage preferred is (a) elastic cartilage (b) hyaline cartilage (c) calcified cartilage (d) fibrous cartilage. 38. In photorespiration, glycine enters from (a) chloroplast to mitochondrion (b) peroxisome to mitochondrion (c) mitochondrion to peroxisome (d) chloroplast to peroxisome. MT BIOLOGY

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39. Cleistogamy is advantageous because (a) hundreds of pollen grains are transferred by each visit of a pollinator (b) more efficient and widespread seed dispersal (c) seed set is not dependent on pollinators (d) it leads to greater genetic diversity. 40. An amniocentesis test on a pregnant woman shows an extra barr body in the embryo, the syndrome which is likely to be associated with embryo is (a) Down’s syndrome (b) Edward’s syndrome (c) Klinefelter’s syndrome (d) Cri du chat syndrome. Directions : In the following questions (41-60), a statement of assertion is followed by a statement of reason. Mark the correct choice as : (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true but reason is not the correct explanation of assertion. (c) If assertion is true but reason is false. (d) If both assertion and reason are false. 41. Assertion : Stomata are found on the surface of leaves in gymnosperms. Reason : In gymnosperms, cuticle of leaves is thin. 42. Assertion: Generally, a woman does not conceive during the first six weeks of lactation period. Reason: The hormone ‘prolactin’ initiates and maintains lactation in a postpartum woman. 43. Assertion: Chromosomal aberrations are caused by a break in the chromosome or its chromatid. Reason: Duplication, deletion, transversion and translocations are the result of chromosomal aberrations. 44. Assertion: The stem tubers are the swollen ends of specialised underground stem branches, which help in vegetative propagation of the plant. Reason: Solanum tuberosum is an example of a stem tuber which stores inulin as the main reserve food material. 45. Assertion : The collenchyma is a thick walled living tissue. Reason : The collenchyma is thickened due to the deposition of pectin and cellulose. 46. Assertion : “Rosie”, the first transgenic cow, produced human protein-enriched milk. Reason : The milk contained the human alpha-( a ) lactalbumin and was more balanced product for human babies than natural cow milk. 47. Assertion : Nitrogen-fixing bacteria in legume root nodules survive in oxygen-depleted cells of nodules. Reason : Legheamoglobin completely removes oxygen from the nodule cells. 20

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48. Assertion : The atmospheric concentration of CO2 at which photosynthesis just compensates for respiration is referred to as CO2 compensation point. Reason : The CO2 compensation point is reached when the amount of CO2 uptake is less than that generated through respiration because the level of CO2 in the atmosphere is more than that required for achieving CO2 compensation point. 49. Assertion : Mitochondria and chloroplasts are semiautonomous organelles. Reason : They are formed by division of pre-existing organelles as well as contain DNA but lack protein synthesising machinery. 50. Assertion : A person who has received a cut and is bleeding needs to be given anti-tetanus injection. Reason : Anti-tetanus injection provides immunity by producing antibodies against tetanus. 51. Assertion : Natural selection is the outcome of differences in survival and reproduction among individuals that show variation in one or more traits. Reason : Adaptive forms of a given trait tend to become more common; less adaptive ones become less common or disappear. 52. Assertion: Acetylcholine participates in the nerve impulse transmission across a synapse. Reason: Acetylcholine is secreted by adrenergic fibres. 53. Assertion : Aschelminthes are called as pseudocoelo-mates. Reason : In Aschelminthes, mesoderm is present as scattered pouches in between ectoderm and endoderm. 54. Assertion : Self-incompatibility is a genetic mechanism which prevents self-pollen (from the same flower or other flowers of the same plant) from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil. Reason : In gametophytic self-incompatibility, the incompatibility reaction is determined by the genotype of the sporophytic tissue of the plant from which the pollen is derived. 55. Assertion : Offsite collections can be used to restock depleted populations, reintroduce species in the wild and restore degraded habitats. Reason : Offsite collections have been successful in saving black-footed ferret and californian condor from extinction. 56. Assertion : A population growing in a habitat with limited resources shows initially a lag phase, followed by phases of acceleration and deceleration and finally an asymptote, when the population density reaches the carrying capacity. Reason : This type of population growth is called VerhulstPearl Logistic growth, in which a plot of N (population density) at time (t) results in a sigmoid curve.

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57. Assertion : Anaerobic respiration sometimes occurs in our skeletal muscles during strenuous exercise. Reason : Pyruvic acid is reduced to lactic acid by lactate dehydrogenase in the absence of oxygen. 58. Assertion : Phenylketonuria is a disease in which excretion of phenylalanine occurs in urine. Reason : It is due to dietary imbalance. 59. Assertion : Aldosterone is a steroid hormone and is important in the control of sodium and potassium ion concentration in mammals. Reason : It upgrades sodium ion concentration in the ECF by promoting reabsorption of sodium ions from renal tubules and excretion of potassium ions in urine. 60. Assertion : Digested and semi-digested food is absorbed directly by body surface in tapeworms. Reason : Digestive organs are absent in tapeworms.

ANSWER 1. 6. 11. 16. 21. 26. 31. 36. 41. 46. 51. 56.

(d) (d) (d) (a) (d) (d) (d) (c) (d) (a) (a) (b)

2. 7. 12. 17. 22. 27. 32. 37. 42. 47. 52. 57.

(b) (a) (c) (b) (b) (a) (d) (b) (b) (a) (c) (a)

3. 8. 13. 18. 23. 28. 33. 38. 43. 48. 53. 58.

KEY 4. 9. 14. 19. 24. 29. 34. 39. 44. 49. 54. 59.

5. 10. 15. 20. 25. 30. 35. 40. 45. 50. 55. 60.

(b) (d) (a) (a) (b) (a) (c) (c) (a) (a) (b) (a) 

RUDOLF VIRCHOW

FATHER OF MODERN PATHOLOGY

udolf Ludwig Carl Virchow, was a renowned and influential German physician and pathologist of the 19th century. He was a pioneer in veterinary pathology and social medicine. He was also an anthropologist, biologist, writer, editor of several medical journals and a statesman noted for his efforts in advancing public health. He was born on October 13, 1821. He was the only child of Carl Christian Siegfried Virchow and Johanna Maria in Schievelbein in Pomerania, Prussia (now known as Swidwin in Poland). He did his elementary schooling in Schievelbein. He graduated from Gymnasium in 1839 and was awarded a military fellowship to study at Berlin’s Friedrich-Wilhelms Institute (now Humboldt University of Berlin) from where he got his medical degree in 1843. After his graduation, he worked under Johannes Peter Muller as a subordinate physician and later did his internship at Berlin’s Charite Hospital. In 1844, Virchow joined Robert Froriep, a prosector, who was also editor of a journal that dealt specially with international work. He studied microscopy under Froriep and developed an interest in pathology. Virchow published his first scientific paper in 1845 in which he wrote the earliest known pathological descriptions of leukemia. He qualified the medical licensure examination in 1846, and immediately succeeded Froriep as hospital prosector at the Charité. In 1847, he was appointed to his first academic position with the rank of privatdozent. With colleague, Benno Reinhardt, he started a journal Archiv für pathologische Anatomie und Physiologie und für klinische Medizini (now known as Virchow’s Archies) in 1847. To fight political injustice he founded Die medicinische Reform (Medical Reform), a weekly newspaper for promoting social medicine, 1848. The newspaper ran under the banners “medicine is a social science” and “the physician is the natural attorney of the poor”. 22

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His first major work was a six-volume Handbuch der speciellen Pathologie und Therapie (Handbook on Special Pathology and Therapeutics) published in 1854. In 1855, he published his famous work describing “omnis cellula e cellula“ (All cells come from cell). He contributed to understand cellular pathology and stated that diseases could be characterised and accurately diagnosed by typical anatomical changes. Among his books, Cellular Pathology, published in 1858 is regarded as root of modern pathology and also popularised, the third dictum of cell theory ‘Omnis Cellula e cellula‘. He created the field of comparative pathology. He founded Zeitschrift für Ethnologie (Journal of Ethnology). The latter is published by German Anthropological Association and the Berlin Society for Anthropology, Ethnology and Prehistory, the societies of which he was the founder. Virchow married Ferdinande Rosalie Mayer (Rose Virchow) in 1850. They had three sons and three daughters. Rudolf died of heart failure, on 5 September 1902, in Berlin. In 1892, he was awarded the British Royal Society’s Copley Medal. His contributions include: • was first person to identify leukemia in 1847. In 1857, he was the first to describe a type of tumor called chordoma that originated from the clivus. • He also explained the mechanism of pulmonary thromboembolism for the first time. • He developed a systematic method of autopsy. • Virchow was the first to analyse hair in criminal investigation and made the first forensic report in 1861. • He also described the life cycle of Trichinella spiralis (roundworm). Virchow was an opponent of Darwin’s theory of evolution. Virchow also contributed to anthropology, paleontolgy and archeology. He believed that the Neanderthal man was a modern Homo sapiens, in which deformations were caused by rickets and arthritis.

Maximise your chance of success in NEET by reading this article. This section is specially designed to optimise your preparation by practising more and more. It is a unit wise series having chapterwise question bank, allowing you to prepare systematically and become more competent. Recall question or single concept question – indicated by a single finger. Application question or question which requires 2 or 3 concepts - indicated by 2 fingers. Application question or question which requires 3 or more concepts - indicated by 3 fingers.

UNIT-II : STRUCTURAL ORGANISATION IN PLANTS AND ANIMALS CHAPTER-5 : MORPHOLOGY OF FLOWERING PLANTS

Multiple Choice Questions 1. Select the incorrectly matched pair. (a) Creepers - stems have roots at intervals (b) Herbs - may have underground stem (c) Trailers - woody climbers (d) Twiners - weak stemmed plants 2. Which of the following statements is correct? (a) Perennial plants can also be monocarpic. (b) Psammophytes grow in rocky substrate. (c) Halophytes are found only in marshy habitats. (d) Lithophytes are adapted to grow in dry habitats. 3. In addition to normal roots, Asparagus is characterised by presence of (a) fasciculated roots (b) palmate roots (c) tuberous roots (d) beaded roots. 4. Which of the following statements is correct regarding the flattened petiole or rachis of a leaf found in desert plants? (a) This flattened structure is called phylloclade which performs photosynthesis. (b) This structure takes part in vegetative reproduction. (c) It bears nodes and internodes. (d) They are rarely succulent. 5. Which of the following inflorescence is a modified spike having bisexual flowers on flattened peduncle?

(a) Umbel (c) Hypanthodium

(b) Capitulum (d) Cyathium

6. Capsules of Papaver, Gossypium and lady’s finger differ in their mode of dehiscence. Select the option that correctly represents their mode of dehiscence in respective manner. (a) Pore, longitudinal slit, irregular manner (b) Pore, longitudinal slit, longitudinal slit (c) Apical teeth, pore, longitudinal slit (d) Septicidal slit, pore, irregular manner 7. Endosperm is fleshy and edible in (a) litchi (b) cashewnut (c) banana (d) rice. 8. Gynandrous condition refers to (a) attachment of stamens with petals (b) attachment of stamens with carpel (c) attachment of stamens with petals as well as carpels (d) stamens with fused anthers. 9. Which of the following is an example of parietal placentation? (a) Tomato (b) Mustard (c) Sunflower (d) Lemon 10. Colchicine is used to introduce polyploidy. It is obtained from Colchicum autumnale that belongs to Family (a) Liliaceae (b) Solanaceae (c) Fabaceae (d) Leguminosae. MT BIOLOGY

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Match The Columns 11. Match Column I with Column II. Column I Column II A. Ligule (i) Broadened hypopodium that completely encloses stem B. Pulvinus (ii) Fused stipules that surrounds the stem C. Amplexicaul (iii) Outgrowth between leaf base and lamina D. Ochreate (iv) Swollen leaf base 12. Match Column I with Column II. (There can be more than one match for items in Column I). Column I Column II A. Hypogynous (i) Mustard B. Epigynous (ii) Racemose C. Perigynous (iii) Monoadelphous D. Stamen (iv) Guava E. Inflorescence (v) China rose (vi) Cucumber (vii) Diadelphous (viii) Rose (ix) Cymose (x) Peach

15. Assertion : Flowers are modified shoot, which perform sexual reproduction. Reason : Different whorls of flower are arranged successively on internodes. 16. Assertion : The mangrove plants possess horizontal cable roots. Reason : Horizontal roots develop both upright aerial roots and downward absorbing roots. 17. Assertion : Viscum has non-green stems and leaves. Reason : Viscum sends primary and secondary haustoria into the host for absorbing food only. 18. Assertion : Floral organs borne on thalamus are commonly arranged in whorls. Reason : Sepals protect floral organs while petals attract pollinating insects.

Figure Based Questions 19. Refer to the given floral diagram and answer the following questions.

Passage Based Question 13. Complete the given passage with appropriate words or phrases. The monocotyledonous seeds possess a single (i) and are generally (ii) . The seed coat is membranous and (iii) with the fruit wall. The main bulk of the grain is (iv) , which store (v) . Endosperm is separated from the embryo by a distinct layer known as (vi) . The embryo is small and occurs in a groove at one end of the endosperm. It consists of one shield-shaped cotyledon known as (vii) , an embryonal short axis with (viii) and (ix) . A sheath called (x) covers the plumule. Likewise, the radicle is protected by (xi) .

(a) State the characteristics of androecium and gynoecium that can be inferred from the above given floral diagram. (b) Identify the plant and the family to which the floral diagram belongs. (c) Give any two economical importance of plants of this family. 20. Refer to the given L.S. of a fruit and answer the following questions. P

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Q R S T

(a) Identify P, Q, R, S and T. (b) Which type of fruit is this? (c) From which parts the outer hard covering and inner papery white covering around the group of seeds are formed in this fruit?

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CHAPTER-6 : ANATOMY OF FLOWERING PLANTS

Multiple Choice Questions 1. Which of the following is not the part of stele? (a) Pericycle (b) Vascular bundle (c) Pith (d) Endodermis 2. Which of the following statements is/are incorrect for the companion cells? I. They are the conducting part of phloem. II. Their nuclei control the activities of sieve tube cells. III. They are associated with the phloem parenchyma through compound plasmodesmata. IV. They help in maintaining the pressure gradient in sieve tube cells. (a) I and II (b) I and III (c) III and IV (d) II and IV 3. Select the correct statement. (a) Vessels do not help in transport but provide mechanical strength. (b) Wood parenchyma helps in lateral conduction of sap. (c) Calyptrogen differentiates in dicots and gives rise to root cap. (d) In sunken stomata, subsidiary cells lie below the guard cells. 4. According to histogen theory of Hanstein (a) dermatogen forms epiblema and root cap in dicots (b) periblem forms cortex, endodermis and pericycle in both root and shoot (c) plerome forms vascular strand and pith in shoot (d) dermatogen forms root cap and cortex in roots. 5. Select the mismatched pair. (a) Hadrocentric bundle - Phloem surrounds xylem (b) Open collateral bundle - Fascicular cambium present (c) Bicollateral bundle - Xylem on both inner and outer side of phloem (d) Radial bundle - Xylem and phloem are on separate radii 6. Endodermis is considered as a ‘biological check post’ because (a) it is present between stele and pericycle (b) it is barrel-shaped and do not have intercellular spaces (c) it is rich in starch grains and have starch sheath (d) it possesses ligno-suberised Casparian strip. 26

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7. Elongation of bamboo and grass stem occurs due to the activity of (a) lateral meristem (b) apical meristem (c) intercalary meristem (d) secondary meristem. 8. Which of the following sequence correctly represents the arrangement of tissues from inner to outer side, after the secondary growth in a dicot stem? (a) Secondary xylem → Primary xylem → Primary phloem → Crushed phloem → Secondary phloem → Phellem → Phellogen → Phelloderm (b) Primary phloem → Secondary phloem → Crushed xylem → Secondary xylem → Primary xylem → Phellem → Phelloderm → Phellogen (c) Primary xylem → Secondary xylem → Secondary phloem → Crushed phloem → Primary phloem → Phellogen → Phelloderm → Phellem (d) Primary xylem → Secondary xylem → Secondary phloem → Crushed phloem → Phelloderm → Phellogen → Phellem 9. Cork cambium in a dicot stem produces (a) cork on outer side and secondary cortex on inner side (b) cork on both outer and inner sides (c) secondary cortex on both the sides (d) secondary vascular tissues on inner side and secondary cortex on outer side. 10. Consider the following statements and select the correct pair of statement regarding secondary growth in stem. I. Cells of xylem rays differentiate to form interfascicular cambium. II. In spring wood, fibres and tracheids are less abundant than in autumn wood. III. Hardwood is porous wood while softwood is nonporous wood. (a) I and II (b) I and III (c) II and III (d) None of these

Match The Columns 11. Match Column I with Column II. Column I Column II A. Mesophyll (i) Passage cells B. Periderm (ii) Isobilateral leaf C. Endodermis (iii) Lenticels D. Subsidiary cells (iv) Accessory cells E. Bulliform cells (v) Palisade cells

12. Match Column I with Column II. (There can be more than one match for items in Column I). Column I Column II A. Exarch xylem (i) Proxylem towards outer side B. Endarch xylem (ii) Centripetal development C. Prickles (iii) Epidermal outgrowth with some inner tissues D. Trichomes (iv) Strictly epidermal outgrowth (v) Centrifugal development (vi) Proxylem towards centre (vii) Absence of vascular supply (viii) Digestive glands of insectivorous plants

Figure Based Questions 19. Refer to the given diagram and answer the following questions. P (a) Identify P, Q, R, S and T. Q (b) Identify the type of vascular bundle in the given figure. R (c) Describe the S characteristics of xylem present in this type of T vascular bundle. 20. Consider the given figure and answer the following questions.

Passage Based Question 13. Complete the given passage with appropriate words or phrases. Dicot stems produce (i) in outer cortical cells. It divides on the outer side to form (ii) , while on the inner side produces (iii) . The phellem or cork cells are (iv) and have deposition of (v). Phellem, phellogen and phelloderm collectively form (vi) . The function of periderm is protective. Bark includes periderm, (vii), (viii), primary and secondary (ix) .

Assertion & Reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as : (a) if both A and R are true and R is the correct explanation of A (b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 14. Assertion : Epidermal cells of cereals have a deposition of silica. Reason : Silica is abrasive and provides stiffness. 15. Assertion : Root apical meristem appears cup-shaped. Reason : Quiescent centre is present in the centre of the root apex. 16. Assertion : Epiblema is also called piliferous layer. Reason : Epiblema bears root hair. 17. Assertion : Leaves of maize gets rolled up to reduce the loss of water in water deficient condition. Reason : Maize have palisade parenchyma in their mesophyll. 18. Assertion : Lenticels are found in woody trees as well as in climbers. Reason : Lenticels are produced by phelloderm.

(a) Identify the structure X. (b) Where is X found? (c) Explain how X is formed. CHAPTER-7 : STRUCTURAL ORGANISATION IN ANIMALS

Multiple Choice Questions 1. Tendon is made up of (a) white fibrous tissue (b) yellow elastic tissue (c) loose connective tissue (d) both (a) and (c). 2. Select the mismatched pair. (a) Merocrine gland - Salivary glands (b) Apocrine gland - Mammary glands (c) Holocrine gland - Gonads (d) Heterocrine gland - Pancreas 3. Which of the following statements are incorrect regarding connective tissues? I. White fibres are made up of collagen fibres and fibroblasts. II. Yellow fibres form ligament that connect skeletal muscle to a bone. III. Tendons are formed by yellow elastic connective tissues. IV. Yellow fibres make cartilage more flexible. (a) I and II (b) I and III (c) III and IV (d) II and III MT BIOLOGY

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4. Pseudostratified ciliated columnar epithelium is found in (a) trachea (b) olfactory mucosa (c) bronchi (d) both (a) and (c). 5. Which of the following is a mismatched pair? (a) Squamous epithelium - Walls of blood vessels (b) Ciliated epithelium - Inner surface of bronchioles (c) Columnar epithelium - Lining of stomach (d) Cuboidal epithelium - Lining of intestine 6. Adipose tissues help in (a) prevention of heat loss (b) production of blood corpuscles (c) absorption of shock by some vital organs (d) all of these. 7. Which of the following is a specialised connective tissue? (a) Cartilage (b) Bone (c) Blood (d) All of these 8. Long bones are covered with ____ at their ends. (a) muscles (b) adipose tissues (c) areolar tissues (d) spongy bones. 9. The stratified columnar epithelium is found in (a) cornea of eye (b) lining of salivary and pancreatic ducts (c) lining of mammary gland ducts (d) lining of larynx and soft palate. 10. Blood of cockroach has the respiratory pigment (a) haemoglobin (b) haemocyanin (c) haemoerythrin (d) none of these.

Match The Columns 11. Match Column I with Column II. Column I Column II A. Tight junctions (i) Minute projections of membrane that connects adjacent cells B. Gap junctions (ii) Helps in anchoring neighbour cells C. Zonula adherens (iii) Prevent exchange of chemicals between adjacent cells D. Intercellular bridges (iv) Exchange chemicals between adjacent cells 12. Match Column I with Column II. (There can be more than one match for items in Column I). 28

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A. B. C. D.

Column I Striated muscle Smooth muscle Cardiac muscle Simple squamous epithelium

(i) (ii) (iii) (iv)

Column II Voluntary Uninucleate fibres Pavement epithelium Pharynx

(v) Involuntary (vi) Alveoli (vii) Intercalated discs (viii) Urinary bladder

Passage Based Question 13. Complete the given passage with appropriate words or phrases. Muscles are made up of highly specialised thin and elongated cells called (i) . Muscular tissues are derived from (ii) layer of embryonic germ cells. Muscular cells are also called (iii) or (iv). These develop from (v) . Each muscle fibre consists of fine fibrils, present in cytoplasm known as (vi) and the membrane of each fibre is known as (vii) . A muscle consists of many muscle fibres arranged in bundles called (viii) which is surrounded by a connective tissue sheath (ix) . Each muscle fibre is surrounded by this connective tissue sheath (x) . The connective tissue that covers the whole muscle is called (xi) .

Assertion & Reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as: (a) if both A and R are true and R is the correct explanation of A (b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 14. Assertion : Endocrine glands do not have ducts. Reason : Endocrine glands secrete saliva and mucus. 15. Assertion : Calcium is necessary for the contraction of muscles. Reason : In presence of calcium ions and ATP, actomyosin is formed. 16. Assertion : Blood can prevent its own excessive loss. Reason : Thrombocytes release platelet factors such as thromboplastin. 17. Assertion : Red bone marrow is present at the epiphyses. Reason : Red bone marrow is gradually replaced by yellow bone marrow. 18. Assertion : Ciliated epithelium helps in the movement of secretions from glands, urine and semen. Reason : Cells of ciliated epithelium are unequal in size and only long cells have cilia at their surface.

Figure Based Questions 19. Refer to the given figure of various human blood corpuscles and answer the following questions.

(a) Identify the cells A, B, C and D and write their major functions. (b) What is the percentage of each of these cells in human blood?

(a) Identify the structures labelled as L, M, N, O and P in the given figure. (b) Which physiological process is performed by these organs? (c) State the role of P during the process performed by the given figure.

20. Study the given figure and answer the following questions.

SOLUTIONS CHAPTER-5 : MORPHOLOGY OF FLOWERING PLANTS

1. (c) 2. (a) 3. (a) 4. (d) 5. (b) 6. (b) 7. (d) 8. (b) 9. (b) 10. (a) 11. A-(iii); B-(iv); C-(i); D-(ii) 12. A-(i, v); B-(iv, vi); C-(viii, x); D-(iii, vii), E-(ii, ix) 13. (i) cotyledon (ii) endospermic (iii) fused (iv) endosperm (v) food (vi) aleurone layer (vii) scutellum (viii) plumule (ix) radicle (x) coleoptile (xi) coleorhiza 14. (a) 15. (c) 16. (b) 17. (d) 18. (b) 19. (a) Androecium of this flower possess five stamens, polyandrous, alternipetalous and epipetalous. Anthers are bithecous, basifixed and inferior. Gynoecium is bicarpellary, syncarpous, ovary is superior, placed obliquely and bilocular. Placentation is axile with many ovules in each loculus. (b) The given floral diagram is of Solanum nigrum which belongs to family Solanaceae. (c) Plants of this family are used as (i) Vegetables e.g., Potato, tomato, brinjal, etc. (ii) Medicines e.g., Atropa belladona yields belladona which is used as topical pain reliever for dilation of pupil of the eye. Roots of Withania somnifera (Ashwagandha) are used to cure rheumatism and general weakness. Different parts of Solanum surattense are useful in treating asthma, bronchitis, leucoderma, etc. 20. (a) P is fused epicarp and thalamus, Q is mesocarp, R is papery endocarp, S are seeds and T represents placenta in fruit.

(b)

(c)

The given figure is of pomegranate (Punica granatum) which is a balausta berry. It is a pseudocarpic berry in which the syncarpous pistil consists of two rows of fused carpels. The hard rind of pomegranate is made up of exocarp and part of mesocarp while the white papery layer that covers the individual groups of seeds is derived from endocarp.

CHAPTER-6 : ANATOMY OF FLOWERING PLANTS

1. (d) 2. (b) 3. (b) 4. (a) 5. (c) 6. (d) 7. (b) 8. (d) 9. (a) 10. (c) 11. A-(v), B-(iii), C-(i), D-(iv), E-(ii) 12. A-(i, ii), B-(v, vi), C-(iii, vii), D-(iv, viii) 13. (i) phellogen (ii) phellem (iii) phelloderm (iv) dead (v) suberin (vi) periderm (vii) cortex (viii) pericycle (ix) phloem 14. (b)

15. (a)

16. (a)

17. (c)

18. (d)

19. (a) P-Bundle sheath, Q-Protophloem, R-Metaxylem, S-Protoxylem, T-Protoxylem cavity (b)

(c)

The given figure shows the conjoint, collateral and closed type of vascular bundle. These are found in monocot stem where a large number of vascular bundles are scattered in ground tissue i.e., atactostele. Xylem is endarch and arranged in the form of letter Y. Metaxylem generally consists of two large oval or rounded vessels lying at the upper two angles of xylem. The metaxylem vessels have pitted walls. Protoxylem has a few (2-3) small oval vessels. They lie at lower angle of xylem. The vessels of protoxylem show spiral and annular thickenings. Xylem parenchyma and a few fibres are found just outside them. Some of the protoxylem vessels and xylem parenchyma cells dissolve or separate during the MT BIOLOGY

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rapid growth of the stem to form a cavity called protoxylem cavity or lacuna. 20. (a) The balloon like structures ‘X’ represent tyloses in dicot stem. (b) Tyloses are found in the heartwood or duramen of older stems. (c) They are formed when tracheids and vessels of the heartwood get plugged by the ingrowth of the adjacent xylem parenchyma into the lumen of xylem vessels through the pits. CHAPTER-7 : STRUCTURAL ORGANISATION IN ANIMALS

1. (a) 2. (c) 3. (d) 4. 6. (d) 7. (d) 8. (d) 9. 11. A-(iii), B-(iv), C-(ii), D-(i) 12. A-(i, iv), B-(v, viii), C-(ii, vii), D-(iii, vi) 13.

(i) (iii) (v) (vii) (ix) (xi)

14. (c)

muscle fibre myocytes myoblasts sarcolemma perimysium epimysium 15. (a)

(ii) (iv) (vi) (viii) (x) 16. (a)

(d) (c)

5. (d) 10. (d)

mesodermal sarcocytes sarcoplasm fasciculi endomysium

17. (b)

18. (d)

19. (a) A is monocyte. It is phagocytic in nature and engulf germs and cellular debris.

(b)

B is eosinophil that is non-phagocytic but its number increases during allergy and plays important role in immune response. C is neutrophil which phagocytose germs and dead cells. D are platelets that help in blood clotting by releasing certain clotting factors. Monocytes - 2-10% Eosinophils - 1-6% Neutrophils - 40-70% Platelets - 2,50,000 per mm3 of blood

20. (a) The given figure shows the structure that constitutes the respiratory system of cockroach. Here, L is spiracle, M is tracheal epithelium, N is atrial muscles, O is tracheae and P are tracheoles. (b)

These structures play an important role during breathing or respiration of the insect.

(c)

Labelled part ‘P’ is tracheoles that terminate blindly in the tissues and contain a tissue fluid at the distal end which plays a significant role during the diffusion of the gases. When the air enters the spiracles, tracheae and tracheoles, oxygen from the air is dissolved into the tissue fluid present in the tracheoles from which it is diffused into the body cells.

Unscramble the words given in column I and match them with their explanations in column II. Column I Column II 1. IEPCLOEN

(a)

The study of reptiles and amphibians.

2. ARPMALYNO

(b)

A covering of dead spongy tissue over aerial roots.

3. RAARCNGIENE

(c)

A false septum that develops between the two parietal placentae in the members of Brassicaceae.

4. REPELOGOYHT

(d)

A gelatin like substance that can be obtained by boiling cartilage in water.

5. LAEVNME

(e)

Fixed macrophages in bone.

6. PEULMR

(f)

Phycocolloid used as a clearing agent in liquors.

7. NOHDCNIR

(g)

Specialised complex carbohydrate as reserve food in Euglenoids.

8. SAEOSLTOSTC

(h)

Epoch known for the divergent evolution of modern mammals.

9. ONALNLI

(i)

The individuals that have exact copies of genetic characteristics of their parent.

10. ESARTM

( j)

A wax that forms a protective water insoluble coating on animal fur.

Readers can send their responses at editor@mtg.in or post us with complete address by 25th of every month to win exciting prizes. Winners’ names will be published in next issue.

MT BIOLOGY

TODAY | MAY ‘17

H GH

YIELD FACTS

Class XI

–

2016

• We have already discussed the general organisation of prokaryotic and eukaryotic cells along with the endomembrane system in previous issue. In continuation to that remaining cell organelles are discussed here. • Cytoplasm contains a variety of organelles. Mitochondria, plastids and peroxisomes are not considered as a part of endomembrane system because their function is not coordinated with the organelles of endomembrane system.

Cell : The Unit of Life - II

– 4 – 1 J&K

3 2

– 1 K-CET

3 Kerala

–

– –

4 2

1 –

AIIMS

AMU

4 4

2014 2013

3 6

2012

AIPMT/NEET

• Mitochondria are cylindrical, double membranous structure having length of about 1.0 - 4.1 µm and a diameter of 0.2 - 1.0 µm. • The outer membrane is smooth and permeable to many metabolites due to presence of protein channels called porins. • The inner membrane is folded into finger like projections called cristae. • Inner membrane and cristae possess mushroom-like projections called elementary particles or oxysomes (F0 - F1 particles). • These particles are related to ATP synthesis during oxidative phosphorylation. • Mitochondrial matrix contains ribosomes (55S to 70S type), double stranded circular DNA (mDNA or mt DNA), RNA and enzymes of Krebs cycle. • Mitochondria are semi-autonomous in nature as they have their own DNA which can replicate independently and produce its own mRNA, tRNA and rRNA to syntheise some of their proteins. New mitochondria are produced by pre-existing mitochondria.

Analysis of various PMTs from 2012-2016

Structure

2015

MITOCHONDRIA • They were first observed by Kolliker in 1880 while the name “mitochondrium”, was given by Benda (1897). • Mitochondria are organelle of aerobic eukaryotes and are absent in prokaryotes and mature RBCs. • They are called power house of cell because they help in cellular respiration and energy generation.

Functions • • • •

Synthesise and store ATPs by oxidation of respiratory substrates i.e., carbohydrates, proteins and fats. Its matrix is the site of aerobic respiration i.e., Krebs cycle. Electron transport system and oxidative phosphorylation takes place in inner mitochondrial membrane. Synthesis of fatty acids, many amino acids as well as storage and release of calcium when required. Ribosomes Mitochondrial matrix (Inner chamber) Outer membrane Inner membrane Intermembrane space (Outer chamber)

Oxysomes Outer chamber

Elementary particles (oxysomes) Head

Porin

Stalk Base

Inner membrane Outer membrane

Intracristal Crista space Respiratory chain A

Cristae Fig.: Ultrastructure of mitochondrium

Fig.: A. Inner membrane with elementary particles, B. Elementary particle.

PLASTIDS • The term ‘plastid’ was introduced by E. Haeckel in 1866 but its clear definition was given by A. Schimper in 1883. • Like mitochondria, they are also semi-autonomous organelles having DNA, ribosomes and RNA molecules. • Plastids have double membrane envelope which store or synthesise various types of organic compound. They are restricted only to plant cells, with exception of some protists. • They develop from colourless precursors called proplastids. They are of three main types depending on colour.

Types of Plastid Leucoplasts

• Colourless, no pigment. • Generally found in non-green cells. • Depending on the type of stored food they are

of 3 types: – Amyloplasts-store starch e.g., potato, rice, wheat. – Elaioplasts-store fats and oil e.g., tube rose. – Aleuroplasts-store protein e.g., aleurone cells of maize grain, endosperm cells of castor.

Chloroplasts • Green in colour, chlorophyll and carotenoid pigments present. • Synthesis of food from inorganic raw materials in the presence of radiation energy. • Chromatophores are chloroplasts found in algae that are non-green, e.g., rhodoplasts in red algae, phaeoplasts in brown algae.

Chromoplasts

• Yellow or reddish in colour, carotenoid pigments present, chlorophyll absent. • Formed from leucoplasts or chloroplasts. • Provide colour to flowers and fruits, which in turn help in their pollination and dispersal. They are also the site of synthesis of membrane lipids.

Structure of Chloroplast • They have various shapes, such as ribbon-like (e.g., Spirogyra), cup-shaped (e.g., Chlamydomonas) and plate-like (e.g., Ulothrix). Chloroplasts of higher plants are generally disc-shaped. 32

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• • • • • • • •

Their size varies in different species. Chloroplasts of higher plants are 4-10 µm in length and 2-4 µm in breadth. Chloroplast has three parts: envelope, matrix and thylakoids. The chloroplast is covered by two membranes, separated by intermembrane space. Matrix or stroma consists of circular dsDNA, RNA, ribosomes (70S), starch grains and enzymes of light and dark reactions of photosynthesis. Thylakoids are membrane lined flattened structures in the stroma. They are stacked at places to form grana. Each granum has 2-100 thylakoids. Thylakoids present between two grana are called Fret channel or stroma thylakoids. Flat membranous tubules that connect the thylakoids of different Outer membrane grana are called stroma lamellae. Inner membrane Thylakoid membrane contains photosynthetic pigments (Chl a, Ribosome Chl b, carotenes, xanthophylls) coupling factors (involved in ATP synthesis) and photosystems I and II. Stroma lamella

Functions • It is the site of photosynthesis as it traps solar energy to convert Starch grains inorganic compounds into organic compounds (carbohydrates). Thylakoid Granum Stroma DNA (stack of (aqueous space) • It liberates oxygen and utilises CO2 to keep the balance of gases thylakoids) in the atmosphere. Fig.: Ultrastructure of chloroplast • It produces ATP and reducing power NADPH for various biochemical reactions. • It stores starch and lipids. • It can change into chromoplasts and provide colour to flowers and fruits for attracting various pollinators.

MICROBODIES • They are small, single membrane bound organelles associated with oxidation reactions (other than those involved in respiration). • These are of two types:

Microbodies

• • • • • • • •

Glyoxysomes

Peroxisomes Discovered by De Duve et al. (1965) by fractionation. Found in all eukaryotic cells i.e., both plant and animal cells. Spherical sac-like structure of size 0.5 - 1.0 µm. Contain enzymes for peroxide biosynthesis. E.g., catalase, special docking proteins called peroxins for obtaining materials from cytosol and ER. In animal cells, they metabolise number of toxic substances and also detoxify alcohol in liver. Breakdown of unusual substances or xenobiotics, which cannot be metabolised by normal enzymes. In plants, they perform photorespiration in association with chloroplast and mitochondria. In root nodules, they convert fixed nitrogen into ureids for transport.

• These are specialised peroxisomes.

• They contain enzymes

for b-oxidation and glyoxylate pathway (conversion of fatty acids into carbohydrates). • Fo u n d i n p l a n t s, germinating oil seeds and some fungi.

Oleosomes (Sphaerosomes) - They are the small, spherical vesicles (0.5 - 1.0 µmin diameter) bound by single membrane. These synthesise and store lipids. They arise from endoplasmic reticulum (ER) and occur abundantly in the endosperm cells of oil seeds. In some tissues, they have hydrolytic enzymes, therefore are considered to have lysosomic activity.

RIBOSOMES • They were discovered by Robinson and Brown in 1953 in plant cells and by Palade in 1955 in animal cells. Palade also coined the term ‘ribosome’. ° and diameter of • They are ribonucleoprotein protoplasmic particles (RNP) without membrane, having length of 200 - 340 A ° 170 - 240 A. MT BIOLOGY

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• • • •

Each ribosome consists of one larger and one smaller subunit. The smaller subunit fits over larger one and requires Mg2+ for binding. They are found in all living cells except RBCs. They occur in cytoplasm of the cell and in organelles like mitochondria and chloroplast. The cytoplasmic ribosomes may remain free in cytoplasm or attached to ER. They are the sites of protein synthesis and are known as protein factories. Chemically ribosome is made of two parts: proteins and rRNA. It has 4 sites for specific attachments: mRNA binding site, A or aminoacyl binding site, P or peptidyl site and E or exit site. The size of ribosome is measured by sedimentation coefficient in the centrifuge and is measured as Svedberg unit called S. Two subunits of 80S ribosome are 60S and 40S while 70S ribosome has 50S and 30S subunits. 33 proteins 18S RNA ° 300 – 340A 5S RNA 28S RNA 40 proteins

Subunit 40S

Subunit 60S 5.8S RNA

21 proteins 16S RNA 5S RNA 23S RNA 34 proteins

Subunit 30S 200 – 290A° Subunit 50S

80S 70S Fig.: Components of 80S and 70S ribosomes.

Functions • Protein factories: Ribosomes are sites for polypeptide or protein synthesis and therefore act as protein factories. • Free ribosomes synthesise structural and enzymatic proteins for use inside the cell. The attached ribosomes synthesise proteins for transport. • Ribosomes provide enzymes (e.g., peptidyl transferase) and factors for condensation of amino acids to form polypeptide. • Ribosome contains rRNAs for providing attaching points to mRNA and tRNAs. Ribosome also has a tunnel for mRNA so that it can be translated properly. • It also provides protection to newly synthesised polypeptide by enclosing it in groove of larger subunit of ribosome.

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CYTOSKELETAL STRUCTURES • They are minute, fibrous and tubular structures that form the structural framework inside the cell and maintain shape of cell, regulate orientation and distribution of cell organelles, intracellular transport and cellular movement.

Cytoskeletal Structures Three types are

• • • • • •

Microfilaments Long, narrow protein filaments, made up of actin, occur in plant and animal cells. Often associate to form hexagonal bundles. Generally occur below plasma membrane and are connected with spindle fibres, ER, chloroplasts, etc. Associated with cleavage furrow at the time of cytokinesis in animal cells. Present in myofibrils of muscle fibres. Form contractile machinery of cell which aids in motility like pseudopodia, plasma membrane undulations, endocytosis, cytoplasmic streaming and movement of cell organelles, microvilli formation, etc.

Microfilament

Actin monomer

Intermediate filaments

• Unbranched, about 10 nm thick, made up of variety of proteins often arranged in a network. • They are of four types: (a) Keratin filaments - Form tonofibrils of desmosomes and keratin of skin (b) Neurofilaments - Form lattice with bundles of microtubules in axons and dendrons of nerve cells to provide strength (c) Glial filaments - Found in astrocytes (d) Heterogeneous filaments - Found in muscles, around nucleus and connected to centriole, plasmalemma, etc. • Provide support to all biomembranes including plasma membrane and nuclear membrane, sarcomeres, desmosomes. • Also provide mechanical strength to axons and dendrons of nerve cells and astrocytes.

6 nm

8-10 nm

Microtubules

• Unbranched, hollow tubules of protein tubulin.

• Present in cytoplasm and is constituent

of spindle fibres, chromosome, centrioles, basal bodies, flagella, cilia, sperm tail, etc.

• Diameter is 25 nm with lateral projection

of 100 – 400A° length. • Help in intracellular transport, movement of nuclei during division, movement of chromosomes during anaphase and movement of cilia and flagella. • Determine the place of cell plate formation. • Play a vital role during differentiation. Protofilaments

a-tubulin b-tubulin

a and b tubulin heterodimers

Intermediate filament

Section of a microtubule

FLAGELLA AND CILIA • They are hair-like microscopic locomotory structures. • Both are structurally similar and have similar parts: – Basal body or Kinetosome - It is also called basal granule. Basal body occurs embedded in the outer part of the cytoplasm below the plasma membrane. It has nine triplet fibrils present on the periphery without a central fibril, though a hub of protein is present. Only sub-fibre A is complete (having 13 protofilaments) while sub-fibres B and C are incomplete as they share some of their protofilaments. – Rootlets - They are striated fibrillar outgrowths which develop from the outer lower part of the basal body and are meant for providing support to the basal body. The rootlets are made of bundles of microfilaments. – Basal plate - It is an area of high density which lies above the basal body at the level of plasma membrane. In the region of basal plate, one sub-fibre of each peripheral fibril disappears. The central fibrils develop in this area. – Shaft - It is the hair-like projecting part of flagellum or cilium. The shaft is covered on the outside by a sheath which is the extension of plasma membrane. Internally, it contains a semifluid matrix having an axoneme of 9 peripheral doublet fibrils and 2 central singlet fibrils. This arrangement is called 9 + 2 or 11-stranded. The two central singlet fibres are covered by a proteinaceous central sheath. They are connected by a double bridge. Each peripheral fibril consists of two microtubules or sub-fibres B and A. The sub-fibre A bears two bent arms, the outer one having a hook made up of protein dynein with ATPase activity. Movement of flagella or cilia occurs due to sliding motion in which dynein arm establishes temporary connection with subtubule B of adjacent doublet fibre. The peripheral doublet fibrils are interconnected by A-B linkers of protein nexin between B sub-fibre of one and inner side arm of A sub-fibre of adjacent fibril. Each of their A sub-fibres sends a radial proteinaceous column to the centre which is called spoke. MT BIOLOGY

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Peripheral doublet fibril (tubulin) Spoke (proteinaceous) Head Central singlet fibril (tubulin)

B A

Linker Flagellar sheath Outer side arm Inner side arm B A

B A

Protofilaments

A B A

A B

A A

Central sheath

Matrix

A B

Transition junction Fig.: Ultrastructure of flagellum

Table:

Fig.: Doublet fibril without arms

Differences between cilia and flagella Cilia

Flagella

(i)

The number of cilia per cell is usually very large (300-14000). The number of flagella per cell is usually 1-4.

(ii)

They are smaller (5-20 µm in length), have smooth surfaces They are longer (100-200 µm in length), may have smooth and occur throughout or major part of the surface of a cell. or possess flimmer surface and are commonly found at one end of the cell.

(iii) They beat in a coordinated rhythm either simultaneously The flagella beat independently. (isochronic or synchronous rhythm) or one after the other (metachronic rhythm). (iv) Cilia produce a sweeping or pendular stroke.

The flagella produce undulatory motion.

(v)

Flagella help in locomotion.

Cilia help in locomotion, aeration, feeding, circulation, etc.

(vi) Cilia may fuse to form undulating membrane.

Fusion of flagella is unknown.

(vii) Flame cells of worms, larval bodies of many invertebrates, Many protists, motile algae, spermatozoa of animals, epithelium of respiratory tract, renal tubules, oviducal funnel, bryophytes and pteridophytes, choanocytes of sponges, etc. gastrodermal cells of coelenterates, zoospores and gametes of thallophytes.

Functions • • • • • • •

Help in locomotion. Create current for obtaining food from aquatic medium. Circulate food in the gastrovascular cavity of coelenterates and help in movement of food and egestion in tunicates. Help in oxygen supply and quick diffusion of carbon dioxide in aquatic organisms. Eliminate dust particles which come with inhaled air in the respiratory tract of land animals. Help in passage of eggs in oviduct, excretory substances in kidneys, etc. Function as sensory organs and help in fusion of gametes.

CENTRIOLES • • • • • •

They are non-membranous organelles having (9 + 0) microtubular arrangement. They are approximately 0.3 – 0.5 µm in length and 0.15 µm in diameter. Usually they are arranged in a group of two at right angles to each other, forming a pair called diplosome. Diplosome is present in specialised part of cytoplasm called centrosphere or kinoplasm. Centrosome is a complex structure formed of centrioles and centrosphere. They are found in almost all eukaryotic animal cells, protozoan protists (except some forms like Amoeba), some fungi and the cells of all those eukaryotic plants where flagellate structures are present in the life cycle. They are absent in angiosperms, higher gymnosperms, some algae and fungi. MT BIOLOGY

TODAY | MAY ‘17

Massule or pericentriolar satellite

9 Triplets

C-A connective (proteinaceous linker)

Y A

Triplet fibril

Central rod (HUB) 9 Spokes Centrosphere Centriole Fig.: Centrosome with pair of centrioles (Diplosome)

Cart-wheel structure

Centriole

Fig.: Ultrastructure of centriole

• Centrioles replicate with the help of massules in S or G2 phase to coordinate in animal cell division. Before nuclear division, the two centrosomes separate and move to opposite ends at the place of spindle pole formation.

Functions • • • •

Centrioles help in cell division by forming microtubule-organising centres (MTOCs). Out of the two centrioles in a spermatozoan, the distal one forms axial filament or tail. Centrioles can be transformed into basal bodies to give rise to cilia and flagella. Centrioles are capable of forming new centrioles with the help of massules which function as nucleating centres.

NUCLEUS • Nucleus was first observed by Leeuwenhoek in RBCs and was first studied by Robert Brown in orchid root cells. • It is the largest cell organelle having double membrane and carry all the genetic information. • Commonly cells are uninucleate, Paramecium caudatum is binucleate having (macronucleus for controlling metabolic activities and micronucleus that contains hereditary information). Cells of bone narrow, striated muscles, several fungi and algae are multinucleate. • A typical interphase nucleus is 5-25 µm in diameter and differentiated into nuclear envelope, nucleoplasm, nuclear matrix, chromatin and nucleolus. Outer nuclear membrane Inner nuclear membrane Nuclear envelope Perinuclear space

Endoplasmic reticulum Nucleoplasm

Euchromatin Heterochromatin Chromatin Fibrous lamina Ribosomes

Nucleolus

Nuclear pore

Chromocentre Karyosome (False nucleolus)

Fig.: Ultrastructure of interphase nucleus

MT BIOLOGY

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Nucleus Nuclear envelope

• Separates nucleus from cytoplasm. It is made up of two lipoprotein and

° thickness. trilaminar membranes, each of 60-90A • Inner membrane is smooth while outer may be smooth or have ribosomes like RER. • Two membranes are separated by 100-500 A° wide space called perinuclear space. • Contains large number of pores that regulate transport of substances inside and outside of the nucleus, e.g., ribosomes, RNAs, proteins, etc.

Nucleoplasm

• Transparent, semifluid, colloidal substance that fills inside the nucleus.

• Contains nucleosides and enzymes for DNA and RNA

synthesis and functioning of nucleoproteins, DNA, RNA, etc. Some proteins of nucleoplasm help in spindle formation. Nuclear matrix

Chromatin

• Hereditary, DNA-protein complex, named by Flemming in 1879. • Occurs in the form of fine overlapping coiled fibres which form a network

• Comprises of two types of intermediate filaments, lamin

• • •

nuclear lamina in which ends of chromatin fibres are embedded. • Nuclear matrix and nuclear lamina form scaffold for chromatin. Attachment sites to telomeric parts, components of nuclear pore complex and impart mechanical strength to nuclear envelope.

• •

called chromatin reticulum. Are distributed throughout the nucleoplasm. Differentiated into two regions-euchromatin and heterochromatin. Based on its size, heterochromatin is known as chromocentre, karyosome or false nucleolus. The whole of chromatin is not functional, generally, only a portion of euchromatin takes part in transcription. During prophase, chromatin condenses to form chromosomes.

A and lamin B.

• Forms a dense layer below the nuclear envelope called

Nucleolus

Perinucleolar chromatin Intranucleolar chromatin

• Discovered by Fontana (1781), described by Wagner (1840) and named by Bowman (1840).

Matrix (Pars amorpha)

• Naked, round or irregular structure, attached to chromatin at specific regions called

Granular portion (Ribosomal precursor)

nucleolar organiser region (NOR).

• Generally 1-4 nucleoli are found in a nucleus. • It is the principal site for the development of ribosomal RNAs, centre for the formation of ribosome components, stores nucleoproteins and is essential for spindle formation during nuclear division.

Table: (i) (ii) (iii) (iv)

Fibrillar portion (RNA fibrils) Fig.: Detailed structure of nucleolus

Differences between euchromatin and heterochromatin

Euchromatin It is narrower, 10-30 nm in diameter. It is somewhat diffused and lightly stained. It forms the bulk of chromatin. It contains active genes and takes part in transcription.

Heterochromatin It is thicker, 100 nm in diameter. It is condensed and darkly stained. It is present at certain places in the chromatin. Heterochromatin does not possess active genes and hence transcription is absent.

(v)

Euchromatin is affected by a number of factors like Heterochromatin is not influenced by these factors. pH, temperature and hormones.

(vi)

Crossing over is quite common.

Hetertochromatin inhibits crossing over.

(vii) It replicates early.

It replicates late in the S-phase.

(viii) Nucleosome strand has minimum coiling.

Nucleosome strand has solenoid coiling.

Functions • It stores genetic information and transmit it to the next generation. • It controls cellular activities like growth, development, reproduction and metabolism. 38

MT BIOLOGY

TODAY | MAY ‘17

• It controls the synthesis of RNAs (mRNA, rRNA, tRNA), enzymes and structural proteins. • It directs cell differentiation, nucleus replication and cell division.

CHROMOSOMES

Two identical

chromatids • They are rod-shaped or thread-like condensed chromatin fibres which appear only during Short arm karyokinesis (late prophase and metaphase). • Their number is fixed in all individuals of same species. Centromere • Shape and size of chromosomes varies in individuals. The shape is more clearly visible in late Scaffold prophase and metaphase when primary constriction becomes distinct. Chromatin loops • Two chromatids are attached by centromere to form a single chromosome. (chromonema) • Depending upon the position of centromere, chromosomes are of four types: – Telocentric - Terminal centromere Long arm – Acrocentric - Centromere is situated close to end Fig.: Structure of chromosome – Sub-metacentric - Centromere occurs slightly away from the middle of chromosome – Metacentric - Centromere present in the middle of chromosome. Satellite Secondary constriction Short Arm Centromere Long Arm Telocentric

Acrocentric

Submetacentric

Metacentric

Fig.: Types of chromosome on the basis of position of centromere

Giant Chromosomes Polytene chromosomes • First reported by E.G. Balbiani in 1881. • Commonly found in salivary glands of insects and thus, also known as salivary chromosomes. Also present in antipodal cells, endosperm cells, etc.

• Length can be 2000 µm (1000 – 16000 times larger than ordinary somatic chromosomes).

• Formed by somatic paring between homologous chromosomes and repeated replication of their chromonemata.

• Conspicuous swellings on polytene chromsomes during certain developmental stages are called puffs. Larger swellings are called Balbiani rings. • In region of puffs or Balbiani rings, DNA strands uncoil, become active and produce number of copies of messenger or mRNA. Puff

Knob Dark bands

Interbands Fig.: Polytene chromosome showing puff

Lampbrush chromosomes • • • •

First seen by Flemming (1882) but described by Ruckert (1892). Highly elongated special kind of diplotene chromosome bivalents. Occur in diplotene stage of animal oocytes, spermatocytes, etc. Total length may be up to 5900 µm or three times the aggregate length of total polytene chromosomes. • Occur in pairs, consist of homologous chromosomes. • Chromomeres give out lateral projections or loops, which provide lampbrush-like appearance to the chromosome pair. Loops are uncoiled parts of chromomere with one to several transcriptional units. Loops are region for rapid transcription of mRNA meant for synthesis of yolk and other substances required for growth and development of meiocytes.

Main axis of chromosome Filament (DNA) Loops Matrix (Protein +RNA)

Matrix (Protein +RNA)

Chromosome axis

Chromomere pair

Fig.: Lampbrush chromosome MT BIOLOGY

TODAY | MAY ‘17

Functions • • • • • •

Contain genes hence, transmit genetic information. Control synthesis of proteins, enzymes, hence regulate cell division, growth and metabolism. Satellite chromosomes produce nucleoli for synthesis of ribosomes. Sex chromosomes (e.g., X and Y) determine sex of individuals. Introduce variations through crossing over. Produce mutations due to change in gene chemistry.

1. Nucleic acids are not present in (a) ribosomes (b) mitochondria (c) chloroplasts (d) peroxisomes. 2. Functional independence of mitochondria and chloroplast from rest of the cellulose machinery is due to (a) presence of double membrane (b) presence of DNA and RNA (c) occurrence of electron transport chain (d) their symbiotic association with prokaryotic cells. 3. Microbodies are involved in the process of (a) respiration (b) photorespiration (c) lipid synthesis (d) protein folding. 4. Match column I with column II and select the correct option. Column I Column II A. Chromonema (i) Fine fibres of DNA protein complex B. Chromatid (ii) Coiled filament that makes chromosome C. Chromatin (iii) Point where chromatids are attached D. Centromere (iv) Identical halves of a chromosome (a) A-(iii), B-(i), C-(ii), D-(iv) (b) A-(i), B-(iii), C-(iv), D-(ii) (c) A-(iv), B-(ii), C-(iii), D-(i) (d) A-(ii), B-(iv), C-(i), D-(iii) 5. Refer to the given figure and select the correct option for A, B, C and D. A C

(a) 40

A is impermeable to biomolecules. MT BIOLOGY

TODAY | MAY ‘17

(b) (c) (d)

Electron transport system is present in B. C has the enzymes for the synthesis of fatty acids. D is responsible for the paternal inheritance.

6. Select the incorrect statement. (a) Different ribosomes of polyribosome are connected by thick strand of mRNA. (b) New chloroplasts arise by the division of proplastids. (c) Microtubules take part in endocytosis and are contractile elements of muscles. (d) Microfilaments are solid structures made of actin proteins. 7. Select the correctly matched pair. (a) Nucleolus - Double membrane (b) Centriole - Without membrane (c) Ribosome - Single membrane (d) Glyoxysome - Without membrane 8. Identify the cytoskeletal structure from the following statements. I. It is a solid filament absent in unicellular eukaryotes. II. It is unbranched and have thickness of about 10 nm. III. It provides mechanical strength to axons and dendrons. IV. It protects skin from abrasions. (a) Microtubule (b) Microfilament (c) Intermediate filaments (d) Both (a) and (b) 9. Which of the following helps in the formation of new centrioles? (a) Centriolar DNA (b) Nuclear DNA (c) Kinoplasm (d) Pericentriolar satellite 10. Given diagram represents the process of formation of ribosomes and its dimer. Select the correct statement in support of this process.

(a) (b) (c) (d)

At higher concentration of Mg2+, ribosomal subunits get separated. Mg2+ is required for binding two subunits of ribosome. Ribosome may occur as monosomes or polysomes. Mg2+ do not play any role in the formation of ribosome.

11. More ribosomes would be found in (a) meristematic cells of plant (b) parenchymatous cells of plant (c) lignified cells of plant (d) dead cells. 12. Lampbrush chromosomes can be seen during (a) diplotene stage (b) metaphase (c) anaphase (d) zygotene stage. 13. Specialised microbody that can be extracted from the endosperm of germinating groundnut seed is (a) ribosome (b) peroxisome (c) lysosome (d) glyoxysome. 14. Study the given table and identify A, B, C and D. Organelle

Function

Nucleolus

Centriole

(a) (b) (c) (d)

Cytoplasmic streaming, endocytosis and exocytosis

Provides sites for polypeptide synthesis and protects newly synthesised polypeptide from cytoplasmic enzymes.

A - Transcription, B - Cytoskeleton formation, C - Microtubule, D - Peroxisome A - Spindle formation, B - Cell plate formation, C - Micro-filament,D - Mitochondria A - rRNA synthesis, B - Sensory organ, C - Intermediate filament, D - Nucleus A - Stores nucleoproteins, B - Synthesise sperm tail, C - Microfilament, D - Ribosome

15. Which of the following is a characteristic of euchromatin? (a) Inhibits crossing over (b) Presence of active genes (c) Distributed throughout the nucleoplasm (d) Does not replicate 16. Puffs or Balbiani rings in polytene chromosomes are sites of (a) DNA replication (b) translation (c) transcription (d) both (a) and (c). 17. Chloroplast ribosomes are (a) 60S (b) 70S (c) 55S (d) 80S.

18. Match column I with column II and select the correct option. Column I Column II A. Free ribosome (i) Endocytosis B. Bound ribosome (ii) Synthesis of ribosomal RNAs C. Chloroplast (iii) Synthesise proteins to be used inside the cell D. Peroxisome (iv) Alcohol detoxification E. Glyoxysome (v) Synthesise proteins for transport (vi) b-oxidation of fatty acids (vii) Synthesise fatty acids (a) A-(ii); B-(i); C-(vi); D-(vii); E-(iv) (b) A-(iii); B-(v); C-(i); D-(vi); E-(iv) (c) A-(v); B-(iii); C-(i); D-(iv); E-(vii) (d) A-(iii); B-(v); C-(vii), D-(iv), E-(vi) 19. Nucleoproteins are synthesised in the (a) nucleolus (b) nucleoplasm (c) cytoplasm (d) nuclear membrane. 20. Microtubule : Tubulin :: Microfilament : ________. (a) Keratin (b) Myosin (c) Actin (d) Both (a) and (c) 21. Ribosomes in animal cells were discovered by (a) Robinson (b) Brown (c) Palade (d) Benda. 22. Chromosome with sub-terminal centromere is called (a) telocentric (b) acrocentric (c) submetacentric (d) acentric. 23. Oxysomes are present in (a) peroxisomes (b) ribosome (c) mitochondria (d) rough endoplasmic reticulum. 24. What is the common feature of chloroplast, chromoplast and leucoplast? (a) They are bound by double membrane and contain photosynthetic pigments. (b) They have thylakoids and grana. (c) They store starch, proteins and lipids. (d) They have the ability to multiply by binary fission. 25. Which of the following does not belong to cell inclusions? (a) Reserve food (b) Secretory product (c) Sap vacuole (d) Mineral matter

ANSWER KEY 1. 6. 11. 16. 21.

(d) (c) (a) (c) (c)

2. 7. 12. 17. 22.

(b) (b) (a) (b) (b)

3. 8. 13. 18. 23.

(b) (c) (d) (d) (c)

MT BIOLOGY

4. 9. 14. 19. 24.

(d) (d) (d) (c) (d)

TODAY | MAY ‘17

5. 10. 15. 20. 25.

(b) (b) (b) (c) (c)  41

-1

Class XI

his specially designed column enables students to self analyse their extent of understanding of specified chapters. Give yourself four marks for correct answer and deduct one mark for wrong answer. Self check table given at the end will help you to check your readiness. • The Living World • Biological Classification Total Marks : 160

Duration : 40 Min.

1. A system of classifying living and extinct organisms in the historical order in which they have evolved from common ancestors, according to their characters, is called (a) cladistics (b) classical taxonomy (c) phenetics (d) numerical taxonomy. 2. Identify the organisms having following features. (i) They are unicellular, usually marine and photosynthetic. (ii) Cells are usually covered by cellulosic plates called theca. (iii) A toxin produced by them causes paralytic shell fish poisoning in humans. (iv) Some of them cause red tides and some show bioluminescence. (a) Chrysophytes (b) Dinoflagellates (c) Slime moulds (d) Euglenoids 3. The book Historia Naturalis was written by (a) Linnaeus (b) John Ray (c) Pliny the Elder (d) Theophrastus. 4. Consider the following statements and select the correct option stating which ones are true (T) and which ones are false (F) regarding binomial nomenclature. (i) The specific epithet can be single or compound and begins with a small letter. (ii) The name of the author is written in Greek script. (iii) The names of families and sub-families should be based on name of genus. (i) (ii) (iii) (a) T F F (b) T T T (c) F F T (d) T F T 42

MT BIOLOGY

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5. Study the given table and identify A, B and C. Feature (i)

Cell wall

Bacteria

Cyanobacteria

1-2 layered

Present

Cyanophycean starch

(ii) Flagella (iii) Carbohydrate reserve food (a) (b) (c) (d)

A 2-layered 3-layered 4-layered 1-2 layered

B Present Absent Absent Present

C Glycogen Starch Glycogen Starch

6. Select the correct option to fill up the blanks in the following statements. (i) _____ has all information about a particular taxon. (ii) A handy book that contains instructions for the collection, identification and occurrence of species in an area is called _______. (iii) ______ contains a list of characters and their alternates to identify various taxa. (i) (ii) (iii) (a) Catalogue monograph Manual (b) Monograph manual Key (c) Key catalogue Manual (d) Monograph manual Catalogue 7. Genus, Family and Class of housefly respectively are (a) Domestica, Diptera, Insecta (b) Musca, Insecta, Arthropoda (c) Domestica, Musca, Insecta (d) Musca, Muscidae, Insecta.

8. Match the following and select the correct option. Column I Column II A. Red rot of sugarcane (i) Alternaria B. Soft rot of apple (ii) Ustilago C. Early blight of potato (iii) Rhizopus D. Loose smut of wheat (iv) Colletotrichum (a) A-(i), B-(iii), C-(ii), D-(iv) (b) A-(ii), B-(i), C-(iii), D-(iv) (c) A-(iv), B-(i), C-(ii), D-(iii) (d) A-(iv), B-(iii), C-(i), D-(ii) 9. Select the incorrect statement regarding mycoplasma. (a) Mycoplasmas are the simplest and smallest free living prokaryotes. (b) It possesses 70S ribosomes and naked DNA. (c) Absence of cell wall makes the organism pleomorphic. (d) None of these. 10. The name ‘Drosophila of plant kingdom’ is given to (a) Aspergillus (b) Claviceps (c) Neurospora (d) Trichoderma. 11. Consider the following figures and identify the correct option regarding A and B.

(a) A is an animal virus with ssRNA and B is a plant virus with dsRNA. (b) A is a bacteriophage containing dsDNA and B is a plant virus having dsRNA. (c) A is plant virus with dsDNA and B is a bacteriophage with dsDNA. (d) A is a plant virus with ssRNA and B is an animal virus with ssRNA.

12. Which of the following is not a useful feature of herbarium? (a) It provides information about the ecology of different places. (b) It provides living plant material for systemic work. (c) It helps in identifying the morphological differences among species. (d) It provides information about flowering season of various plants. 13. Sexual reproduction in deuteromycetes (a) occurs through planogametic copulation (b) occurs through gametangia copulation

14. Identify the organism from the given characteristics. (i) They are the smallest self replicating particles discovered by Diener. (ii) They are known to cause diseases only in plants. (iii) Initiation codon is absent for protein synthesis. (a) Prions (b) Viroids (c) Virus (d) Mycoplasmas 15. Match column I with column II and select the correct option given below. Column I Column II A. John Ray (i) Father of Botany B. Aristotle (ii) Historia Generalis Plantarum C. Theophrastus (iii) New systematics D. Julian Huxley (iv) Father of Zoology (a) A-(ii), B-(iv), C-(i), D-(iii) (b) A-(i), B-(iii), C-(ii), D-(iv) (c) A-(ii), B-(i), C-(iv), D-(iii) (d) A-(iii), B-(iv), C-(i), D-(ii) 16. Which of the following statements is correct regarding cats and leopards? (a) Both belong to Genus Felis (b) Both belong to Family Felidae (c) Both have different genus and family (d) Cats belong to Family Felidae and leopards belong to Family Canidae 17. Which of the following is not a method of reproduction in lichens? (a) Oidia (b) Progressive death and decay (c) Isidia (d) Soredia 18. Clostridium butylicum and Bacillus megatherium respectively are used for preparing (a) chloromycetin, bacitracin (b) riboflavin, cobalamine (c) terramycin, bacitracin (d) cobalamine, ascorbic acid. 19. Which of the following features is not correct for the bacterial cell wall? (a) It provides shape and structural support to the cells. (b) It is 20-80 nm thick, smooth and single layered in Gram negative bacteria. (c) The cell wall contains teichoic acids that form receptor sites and surface antigens in Gram positive bacteria. (d) It protects the bacterial cell from bursting in hypotonic solution. MT BIOLOGY

TODAY | MAY ‘17

20. Select the mismatched pair. (a) Order - Primata (b) Genus - Mangifera (c) Class - Poales (d) Family - Canidae 21. Complete the following table by correctly identifying X, Y and Z in context to photosynthetic protists.

(i)

Group

Reserve food

Example

Dinoflagellates

Noctiluca

Leucosin and oils

Euglena

(ii) Chrysophytes (iii) Euglenoids (a) (b) (c) (d)

X Starch and oils Glycogen Paramylum bodies Starch and oils

Y Cymbella Phacus Pleurosigma Amphipleura

Z Glycogen Woronin bodies Starch and oils Paramylum bodies

27. Which of the following are characteristics of members of Kingdom Protista? (i) Nucleus is present and DNA is associated with histone proteins. (ii) All organisms are heterotrophic with absorptive type of nutrition. (iii) Sap vacuoles are absent. (iv) Cytoplasmic ribosomes are 80S while organelle ribosomes are 70S. (a) (ii) and (iv) only (b) (i), (iii) and (iv) only (c) (i) and (iv) only (d) (i), (ii) and (iii) only 28. ______ created a separate kingdom for organisms on the basis of presence and absence of true nucleus. (a) Linnaeus (b) Copeland (c) Haeckel (d) R.H. Whittaker 29. Select the correct set of differences among the following types of taxonomy.

22. Identify the incorrect pair. (a) Superfamily - Obligate category (b) Symbiotic protist - Trichonympha (c) Simpson - Systematics (d) Weed of laboratory - Aspergillus 23. Which of the following principles is not used as a criterion for delimiting a species of prokaryotes? (a) Morphological differences (b) Interbreeding (c) Chemotaxonomy (d) Cytotaxonomy 24. Select the option which depicts correct taxonomical hierarchy. (a) Species → Genus → Family → Class → Order (b) Species → Genus → Class → Order → Family (c) Genus → Family → Order → Class → Phylum (d) Genus → Family → Order → Phylum → Class 25. Which of the following characteristics can be considered as a defining property for a living organism? (i) Consciousness (ii) Organisation (iii) Growth (iv) Reproduction (v) Metabolism (a) (i), (ii), (iii) and (v) only (b) (i), (ii), (iv) and (v) only (c) (ii), (iii) and (iv) only (d) (i), (ii) and (v) only 26. Identify the correctly matched pair. (a) Symbiotic bacteria - Frankia (b) Parasitic bacteria - Pseudomonas (c) Saprotrophic bacteria - Xanthomonas citri (d) Chemoautotrophic bacteria - Chlorobium limicola 44

MT BIOLOGY

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Classical taxonomy

Modern taxonomy

(i)

It deals with biological species.

It deals with morphology of species.

(ii)

It has a typological concept.

It has a biosystematic concept.

(iii) Species are considered to be dynamic.

Species are considered to be static.

(iv) It is not based on evolution and inter-relationships of species.

It is based on primitiveness, advancement and inter-relationships of species.

Contributed by : Saurabh Kalra, Chandigarh

SOLUTIONS TO MARCH 2017 CROSSWORD 1

T E

A 8

O 22

N 20

K 12

13 16 21

P H

Y T

T I

N 25

O N

T M

O A

(a) (i), (ii) and (iv) only (c) (i) and (iii) only

(b) (ii), (iii) and (iv) only (d) (ii) and (iv) only

F F

T T

T F

30. Which of the following statements are correct regarding the characteristics of halophiles? I. In anaerobic conditions they may reduce sulphur to H2S. II. They are able to survive in high salt conditions due to mucilage covering and high internal salt content. III. Red carotenoid pigment in their cell membrane protects them from harmful solar radiations. (a) I and III (b) I and II (c) II and III (d) I, II and III.

35. The branch of science that deals with principles and procedures for identification, nomenclature and classification of organisms is called (a) characterisation (b) biosystematics (c) classification (d) taxonomy.

31. Read the following statements and select the correct option. Statement A : Scientific names are either derived from Latin language or are latinised. Statement B : Latin is used extensively all over the world and has not changed with time. (a) Both statements A and B are correct and statement B is the correct explanation of statement A. (b) Both statements A and B are correct but statement B is not the correct explanation of statement A. (c) Statement A is correct but statement B is incorrect. (d) Both statements A and B are incorrect.

37. The phylogenetic system of classification was first proposed by (a) Engler and Prantl (b) Hutchinson (c) Julian Huxley (d) Takhtajan.

32. Which of the following is a flagellated protozoan? (a) Plasmodium (b) Paramecium (c) Monocystis (d) Leishmania 33. Ananya saw a black fungus growing on some stale bread. She must classify it under the Class (a) Deuteromycetes (b) Basidiomycetes (c) Ascomycetes (d) Phycomycetes. 34. Read the given statements and select an option stating which ones are true (T) and which ones are false (F)? (i) Prions are highly resistant glycoproteins causing infections such as scrapie of sheep. (ii) Genus is always polytyptic. (iii) Largest botanical gardens in India is in Kolkata. (iv) A class is a taxonomic category which includes one or more related families. (i) (ii) (iii) (iv) (a) T T F F (b) T F F T

36. Which of the following is not a method of ingestion in Amoeba? (a) Invagination (b) Circumvallation (c) Cyclosis (d) Circumfluence

38. Choose the incorrect statement out of the following. (a) Euglenoids have dual mode of nutrition - photosynthetic in light and holozoic in dark. (b) Sexual reproduction in unicellular yeast is similar to that of some multicellular fungi. (c) Phenetic classification is based on evolutionary relationships of organisms. (d) Mode of nutrition was a criteria for classification of organisms into the five kingdoms by Whittaker. 39. Read the following statements and select the option that correctly fill the blanks. (i) In Paramecium, the undigested food is passed out through _____. (ii) In Entamoeba histolytica, the infective stage is _____. (iii) In Euglena, the eye spot contains a red pigment called _____. (i) (ii) (iii) (a) cytostome minuta halorhodopsin (b) cytopyge tetranucleate cyst astaxanthin (c) cytostome microcyst halorhodopsin (d) cytoproct binucleate cyst astaxanthin 40. Which of the following protozoan is an endoparasite and lacks locomotory organelle? (a) Leishmania (b) Entamoeba (c) Monocystis (d) Balantidium Key is published in this issue. Search now! J

Check your score! If your score is > 90%

ExcELLEnT wOrk !

You are well prepared to take the challenge of final exam.

No. of questions attempted

……

90-75%

GOOD wOrk !

You can score good in the final exam.

No. of questions correct

……

74-60%

sATIsfAcTOrY !

You need to score more next time.

Marks scored in percentage

……

< 60%

nOT sATIsfAcTOrY! Revise thoroughly and strengthen your concepts.

MT BIOLOGY

TODAY | MAY ‘17

SYNAPSE

CONCEPT

MAP

Synapse is an anatomically specialised junction between two neurons, where the axon (or some other portion) of one cell (neuron) terminates on the dendrites or some other portion of another cell. The term 'synapse' was first introduced by Charles Sherrington (1924). Transmission of nerve impulse takes place across a synapse between neurons or neurons and an effector. The neuron which sends messages is called presynaptic cell whereas the neuron which receives messages is postsynaptic neuron. Sending neuron Receiving neuron

STRUCTURE OF SYNAPSE Most of the synapses comprise the following structures: (i) Synaptic knob – Terminal bulbous ending of presynaptic axon which is devoid of neurofilaments but its cytoplasm contains: (a) Synaptic vesicles – Small vesicles present in presynaptic cytoplasm that contain neurotransmitters (for excitation or inhibition), like acetylcholine, GABA, etc. (b) Mitochondria, ER and microtubules. (c) Presynaptic membrane – Nerve membrane which is in close approximation with membrane of postsynaptic cell. (ii) Sub-synaptic and postsynaptic membrane – The surface of the cell membrane involved in the synapse is called the sub-synaptic membrane and the remaining of the motor neuron cell membrane is called the postsynaptic membrane. Receptor sites for neurotransmitters are usually located on the subsynaptic membrane.

Sending neuron Action potential Vesicle containing neurotransmitters Axon terminal

Synaptic gap

Presynaptic membrane Postsynaptic membrane

Receptor sites on receiving neuron

TYPES OF SYNAPSE

Neurotransmitter

Axo-dendritic Synapse Axo-dendritic synapse Axo-axonal synapse

Axo-axonal Synapse Synapse between axons of two neurons. It is present in spinal cord.

Synapse between fine terminal branches of axon of one neuron and dendrites or cell body of another neuron. It is located in motor neurons in spinal cord, excitatory synapse in the cerebral cortex, etc.

Synapse between dendrites of two neurons, but is rare. It is present between mitral and granule cell in the bulb.

Signals are transmitted across synaptic cleft in form of chemical messenger – a neurotransmitter, released from presynaptic axon terminal. Chemical synapse operates only in one direction, as neurotransmitter is stored on the presynaptic side of synaptic cleft, whereas receptors for neurotransmitters are on postsynaptic side.

Electrical Synapse

Presynaptic neuron

Chemical Synapse

Microtubule Cytoplasm

Presynaptic neuron

Synaptic vesicle

Mitochondrion

Myelin Gap junction Presynaptic membrane

Postsynaptic neuron

Postsynaptic neuron Ions flow through gap junction channels

Axo-somatic synapse

Dendro-dendritic Synapse l

Dendrite

Axon

Dendro-dendritic synapse

Chemical Synapse

hy s y

ox vo imi us t y a sys nd tem

asi so fp

g lo io

r fp r s o ne asi e b thin On th ion wi locat

On the b

Synaptic vesicle fusing

Neurotransmitter released

Presynaptic membrane

Synaptic cleft

Axo-somatic Synapse Synapse between axon of one neuron and soma of another neuron. It is present in motor neurons in spinal cord and autonomic ganglia.

Postsynaptic membrane

Gap junction channels

Postsynaptic neurotransmitter Ions flow through Postsynaptic receptor postsynaptic channels membrane

Electrical Synapse l l

Here pre-and postsynaptic membrane are joined by gap junctions, through which ions can pass easily. Impulse transmission across electrical synapse is faster than chemical synapse because of the direct flow of electrical current from one neuron to another through gap junction,

MECHANISM OF IMPULSE CONDUCTION

At Electrical Synapse

PROPERTIES OF SYNAPSE l

Convergence and Divergence : Many presynaptic neurons converge on any single postsynaptic neuron, e.g., in spinal motor neurons, some inputs come from dorsal root, some from long descending spinal tracts and many from interconnecting neurons. The axons of most presynaptic neurons divide into many branches that diverge to end on many postsynaptic neurons. Fatigue : Repeated stimulation of presynaptic neuron leads to gradual decrease and finally disappearance of the postsynaptic response. This is due to exhaustion of chemical transmitter, as its synthesis is not as rapid as the release. Synaptic Delay : When an impulse reaches the presynaptic terminal, there is a gap of about 0.5 msec., before a response is obtained in postsynaptic neuron. This is due to the time taken by synaptic mediator to be released and to act on postsynaptic membrane. Synaptic Plasticity : Plasticity implies the capability of being easily moulded or changed. Synaptic conduction thus can be increased or decreased on the basis of past experience. These changes can be presynaptic or postsynaptic in location and play an important role in learning and memory.

At Chemical Synapse Mechanism of chemical transmission across a synapse is as follows: Action potential arrives at axon terminal

Voltage gated Ca2+ ion channels open and electrochemical gradient favours influx of Ca2+ and Ca2+ flows into axon terminal

Ca2+ ions cause synaptic vesicles to move to the surface of the knob and fuse with synaptic membrane terminal

Vesicles release neurotransmitters by exocytosis

Neurotransmitters diffuse across synaptic cleft and bind to receptors on postsynaptic membrane

This causes depolarisation and generation of action potential in the postsynaptic membrane.

l Gap junctions in electrical synapse allow the local currents resulting from arriving action potentials to flow directly across the junction from one neuron to the other. l This depolarises the membrane of the second neuron to threshold, continuing the propagation of the action potential.

The syllabus for NEET is very vast which impedes students from acquiring indepth knowledge and covering the entire syllabus at the same time. An essential topic for NEET is therefore presented here to enable students grasp the topic, analyse the type of questions and SCORE HIGH.

HUMAN FEMALE REPRODUCTIVE SYSTEM

Primary sex organs

Secondary sex organs

Ovaries Oviducts

MT BIOLOGY

Uterus

TODAY | MAY ‘17

Cervix

Vagina

Female Reproductive System

Human beings exhibit sexual dimorphism, i.e., male and female individuals are differentiated externally. Such characters that distinguish the males and females externally are referred to as secondary sex characters. While anatomically, they show distinct specific set of organs constituting the reproductive system. The male and female reproductive systems have evolved according to their respective functions and contributions in the events of human reproduction. The reproductive system in general comprises of: • Primary sex organs, i.e., gonads that produce gametes as well as sex hormones. • Secondary sex organs that do not produce gametes or hormones but play an important functions in process of reproduction. • External genitalia • Accessory glands Vulva External genitalia

Mammary glands

Vestibular glands

Accessory glands

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Infundibulum Funnel-shaped fimbriated free end of the oviduct, opens into the body cavity by an aperture called ostium.

Vaginal artery

Isthmus Short, narrow thick-walled portion that follows the ampulla.

Uterine part Passes through the uterine wall and communicates with uterine cavity.

Broad ligament supports uterine tubes, uterus and vagina

Uterine tube

Cornua Upper corners where the oviducts enter the uterus.

Ovarian ligament attaches the ovary to the uterus.

Round ligament of uterus

Mesovarium anchor the ovary in between.

Ovary Paired, almond-shaped structures, 2-4 cm in length. Located in upper pelvic cavity and held in place by several ligaments. The ovary is covered by germinal epithelium and tunica albuginea. The ovarian stroma consists of cortex (outer dense layer) and medulla (inner less dense layer).

Vagina About 10 cm long tube, extends from the cervix to the outside of the body. The opening of the vagina is called the vaginal orifice. It is partially covered by a membrane called hymen.

Cervix Small narrow cylindrical inferior extremity of uterus which is about 2.5 cm in length, communicates above with the body of the uterus by an aperture called internal os and with the vagina below by external os.

Uterine cavity or uterus A hollow muscular, inverted pear shaped structure, lies in the pelvic cavity between urinary bladder and rectum.

Body of Uterus The main part of uterus. It is broad towards the fundus and narrows down towards the cervix.

Internal os (internal orifice)

Fundus Upper domeshaped region of the uterus which lies above the level of entry of oviducts.

Parts of Uterus

Fig.: Female reproductive system showing primary and secondary sex organs

Cervical os (external orifice)

Cervical canal (cavity of cervix) The cavity between the internal os and external os.

Uterine artery and vein

Endometrium: Inner glandular layer that lines the uterine cavity and undergoes cyclical changes during menstrual cycle.

Myometrium: Middle thick layer of smooth muscle fibres which shows strong contraction during delivery of the baby.

Perimetrium: Outer thin covering of peritoneum.

Ampulla The widest and the longest part of Fallopian tube where fertilisation of the ovum generally takes place.

Fallopian tubes or oviducts 10-20 cm long and comprises of following regions

Suspensory ligament anchor the ovary laterally to the pelvic wall.

Fimbriae Help in collection of the ovum after ovulation, have folds lined with cilia that produce a slow current towards ostium for the passage of liberated ovum towards inside of oviduct.

Wall of Uterus

External Genitalia (Vulva): The external genitalia in human female is collectively called vulva. Mons pubis is anterior most portion, cushion of fatty tissues covered by skin and pubic hair. Clitoris Homologous to glans penis of male, contains erectile tissue.

Clitoral hood Labia majora Two large fleshy folds of skin, homologous to the scrotum of male.

Urethral opening Small opening of urethra below clitoris through which urine is excreted.

Labia minora Two smaller folds of skin, homologous to penile urethra of male.

Hymen remnants Vaginal opening Opening of vagina which provides passage for menstrual flow and insertion of penis.

Fourchette Posteriorly fused labia minora. Perineum Extends from fourchette to anus.

Anus Opening of rectum to outside through which faecal material is expelled out.

Fig.: External genitalia in human female

Accessory Glands Vestibular glands • These are present in external genitalia. They are of two types: Lesser vestibular glands /Paraurethal glands/ Glands of Skene

Greater vestibular glands/Bartholin’s glands

• Numerous small glands present on both sides of the urethral

• Paired glands present one on each side of the vaginal opening. • Homologous to the Cowper’s glands of male and secrete viscid

opening.

• Homologous to the male prostate and secrete mucus.

fluid for lubrication.

Mammary glands • Mammary glands or breasts are modified sweat glands comprising of glandular tissues that form mammary glands, connective tissues and adipose tissue. Fat Mammary skin Mammary duct alveoli open into mammary tubules that join to form a mammary duct.

Ribs

Intercostal muscles Mammary ampulla Muscles between ribs Wider opening of several mammary duct where some milk may be stored temporarily. Pectoralis major muscle Lactiferous duct Mammary lobes Carries milk from one of the lobes to exterior. Approx. 15-25 lobes radiate Nipple around and open at the nipple. Multiporous tip for the release of milk, through this milk is sucked out. Interlobular connective tissue Areola Supports alveoli and the ducts. Circular pigmented area around nipple due to presence of numerous sebaceous glands. Mammary alveoli Produce milk in lactating woman. Fig.: Females’s breast in sagittal section

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• Lactation (milk secretion and ejection) is the main function of mammary glands. • During pregnancy, mammary glands grow under the influence of hormones estrogen and progesterone. At the time of

infant’s birth, the hormone prolactin stimulates the production of milk and the hormone oxytocin causes release of milk as the infant sucks the breast.

Functions of Female Reproductive System Ovaries • Production and secretion of female sex hormones. • Germinal epithelial cells of ovary produce ova by oogenesis.

Fallopian tubes

Uterus

Vagina

• Convey the ovum from

• If fertilisation takes place, then the embryo

• It provides a passage

the ovary to the uterus by peristalsis. • These are sites of fertilisation, i.e., fusion of gametes in ampullary isthmic junction.

gets attached to the uterine wall which protects and nourishes the developing fetus, i.e., implantation. • It is involved in uterine movements and also goes through menstrual cycle, after puberty.

for the menstrual flow and receives sperms during intercourse. • It also acts as a birth canal during labour.

Secondary Sexual Characteristics in Female • General build up – less muscular

• Breathing – shows axillary hair growth and • Shoulders development of pubic hair • Mammary glands – well developed • Shape • Skin – less hairy and coarse • Voice – high pitched • Hair growth

– predominantly thoracic – are not so broad as compared to men – attains feminine shape, i.e., widening of pelvis, deposition of fat in thighs, buttocks and face

OOGENESIS • The process of formation of a mature female gamete (ovum) is called oogenesis. It occurs in ovaries and involves three • •

• • •

phases-mutliplication, growth and maturation. At birth, ovaries contain approx. 2 to 4 million oogonia (egg mother cells). No more oogonia are formed and added after birth. During fetal life, all the oogonia develop into primary oocytes. Then they undergo a first meiotic division by replicating their DNA, however, they do not complete the division in the fetus. Accordingly, all the primary oocytes present at birth are said to be in a state of meiotic arrest containing 46 chromosomes, each with two sister chromatids. The first polar body may divide to form two second polar bodies. They did not play any role in reproduction and soon degenerate due to lack of cytoplasm and food. The actual female gamete is ovum. From one oogonium, one ovum and three polar bodies are formed. The steps in oogenesis can be illustrated as:-

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Stages in Oogenesis

Chromosomes number per Events mitosis cell Oogonia 46 Cells of germinal epithelium divide to (Multiplication Fetal life phase) produce oogonia which multiply by mitotic Mitosis divisions forming the primary oocytes. differentiation 46 Meiosis begins in the primary oocytes soon Primary oocyte after their formation. However, the oocytes Birth are arrested in the meiotic prophase I. This (Growth phase) 1st meiotic division is the first resting stage. They undergo a (begins in utero, round of DNA synthesis, and chromosome completed prior to Childhood pairing takes place. There is accumulation ovulation) of food materials and other resources for Puberty nourishment of the oocyte. First polar 23 Primary oocyte continues meiosis I and Secondary oocyte body (Maturation produces first polar body and secondary Second phase) Adult 2nd meiotic division polar oocyte. reproductive (completed after body life The secondary oocyte proceeds with meiosis fertilisation) II but gets arrested in metaphase II stage. This is the second resting stage. Ovum Only those primary oocytes destined for ovulation complete the first meiotic division which occurs just before the mature follicle is ovulated. The second meiotic division occurs in Fallopian tube after ovulation, but only if the secondary oocyte is fertilised, i.e., penetrated by a sperm.

Hormonal Control of Oogenesis

Hypothalamus GnRH

• Induces rupture of mature

Anterior lobe of pituitary

Graafian follicle and release of secondary oocyte (ovulation). • Stimulates development of corpus luteum which secretes progesterone.

• Stimulates growth of Graafian

FSH

follicle and development of oocyte within follicle to complete meiosis I to form secondary oocyte.

Ovary

• Stimulates formation of estrogen.

Significance of Oogenesis Formation of one ovum and three polar bodies.

Crossing over in meiosis I brings about variations.

Maintains half the number of chromosomes in ovum (haploid condition) by forming polar bodies.

ANSWER KEY

MPP-1 CLASS XI MARCH 2017 1-c- PLASMOTOMY 2-i- NYCTINASTY 3-a- PELOTONS 4-f-ELECTROFUSION 5-h- CHAPERONES 6-e-FIBRILLATION 7-j- HISTAMINE 8-d- HOLOGYNIC 9-g- ATAVISM 10-b-VITELLOGENESIS Winners : Joydeep Saha (West Bengal) , Rida Sood (Delhi), Tanmay Kumar (Ranchi), Gaurang Sodani (Gurugram), Aadvik Ahuja (Nainital)

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1. 6. 11. 16. 21. 26. 31. 36.

(a) (b) (d) (b) (d) (a) (c) (c)

2. 7. 12. 17. 22. 27. 32. 37.

(b) (d) (b) (a) (a) (c) (d) (a)

3. 8. 13. 18. 23. 28. 33. 38.

4. 9. 14. 19. 24. 29. 34. 39.

(d) (d) (b) (b) (c) (d) (d) (b)

5. 10. 15. 20. 25. 30. 35. 40.

Follicular Development • During the course of maturation, the primary oocyte become surrounded by a single layer of squamous follicular cells, to

form basal lamina called primordial follicle. It remains arrested at the diplotene stage of the first meiotic division till the onset of puberty. • At puberty, oogenesis is resumed and the basal lamina around the primary oocyte becomes cuboidal to form primary follicle. • As the development proceeds in primary follicle, the follicular cells keep dividing to form several layers around the primary

oocyte and are known as granulosa cells. • The primary oocyte secretes an acellular glycoprotein layer around itself, called the zona pellucida. The innermost layer of

granulosa cells around the zona pellucida consists of columnar cells and is known as the corona radiata. • The granulosa cells are in communication with the growing oocyte by microvilli on their surface which interdigitate with

those on the surface oocyte to facilitate the exchange of material between them. • As the granulosa cells keep on dividing, a small cavity appears between these cells called the antrum which is filled with

a fluid, liquor folliculi, secreted by the granulosa cells. At this stage the follicle is known as an antral follicle or the secondary follicle. • Around the granulosa cells, connective tissue of ovarian stroma gets differentiated into two layers: a vascular theca

interna and a fibrous theca externa. • Blood vessels in the thecal layer cannot transverse the membrane, so the granulosa layer is completely avascular. • The antrum keeps enlarging with the developing oocyte so that the oocyte is suspended in this fluid-filled cavity by a stalk

of granulosa cells surrounding this oocyte. These are known as cumulus oophorous. • The fully formed mature dominant follicle with a large antrum is called Graafian follicle. It has a primary oocyte, which

is still in meiotic arrest. Just before ovulation this primary oocyte completes its first meiotic division to form a haploid secondary oocyte and a polar body. Meiosis II is initiated but arrested at the metaphase stage. • This secondary oocyte, along with its cumulus oophorous, is released in the peritoneal cavity at ovulation from where it is

picked up by the fimbriae of the oviduct. • The ovulated secondary oocyte is carried into the Fallopian tube where fertilisation occurs. • The remnants of the ovulated follicle in the ovary form the corpus haemorrhagicum that has a blood clot in the centre due

to rupturing of the blood vessels supplying the thecal layer. • This clot is dissolved later and the granulosa and thecal cells of the ruptured follicle are transformed and converted into lutein

cells having yellow carotene pigment or lutein. These transformed cells form corpus luteum which secretes the hormones progesterone and estrogen. The corpus luteum is maintained for about 20 days. • If fertilisation occurs and a conceptus is formed, then the corpus luteum receives a signal from the conceptus and the corpus

luteum is maintained for a long time to support pregnancy. • In the absence of any such signal from the conceptus, the corpus luteum degenerates. This degenerating corpus luteum is

known as the corpus albicans and leads to menstruation. Follicular growth and atresis – Only one ovarian follicle matures and ovulates in an adult woman in every menstrual cycle, alternatively by the two ovaries. So, only about 450 of the total follicles mature during the entire reproductive span. The rest of them degenerate at different times. The degenerating process is called follicular atresia. This is an example of programmed cell death or apoptosis. – Due to this developmental pattern, eggs ovulated near age 50 are 35 to 40 years older than those ovulated just after puberty. Certain chromosomal defects or abnormalities among children born to older women may be the result of ageing changes in the eggs. MT BIOLOGY

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Granulosa cells Zona pellucida Oocyte with nucleus

Secondary follicle (early) Oocyte Basal lamina

Primary follicle

Theca Granulosa cells

Theca Graafian follicle (secondary follicle-mature)

Primordial follicles Germinal epithelium Mesovarian

Theca externa Theca interna Granulosa cells Antrum with estrogen rich follicular fluid

Blood vessels Corpus albicans Regressing corpus luteum

Ruptured follicle Released ovum

Mature corpus luteum

Atretic follicle Blood clot (corpus haemorrhagicum)

Young corpus luteum Fig.: Cross-section of ovary showing stages of follicular growth

Structure of Ovum

Cells of the Zona pellucida Human ovum is spherical in shape. corona radiata Plasma membrane It is alecithal, i.e., free of yolk. Cytoplasm Polar bodies Cytoplasm is called ooplasm. Nucleus Nucleus is large with prominent nucleolus, and is called germinal vesicle. The cytoplasm is enveloped by plasma membrane, below which are present small Cortical Ovum cortical granules. To its outerside is present a narrow perivitelline space. granules • A thick noncellular zona pellucida is present outer to perivitelline space and outer to this a very thick cellular corona radiata is present. • The side of ovum extruding polar bodies is called animal pole while the opposite Fig.: Structure of ovum side is called vegetal pole.

• • • • •

Differentiation of Oocyte into Ovum • Oocyte shows certain structural and cellular changes while differentiating into an ovum. Such as: • Nuclear changes – Production of large amount of nuclear sap resulting in enlarged nucleus. Nucleolus also

increases in its size. • Cytoplasmic changes – Mitochondria increase in number during growth of the oocyte.

– Golgi bodies either disappear or are converted to some other structures. – ER are devoid of ribosomes but their membranes remain perforated by pores. – Formation of cortical granules, these are spherical bodies containing mucopolysaccharides, bound by a simple membrane.

MENSTRUAL CYCLE • Menstruation is the bleeding from the uterus of adult females at an average interval of 28/29 days. The cycle of events

starting from one menstruation till the next one is called menstrual cycle. • The first menstruation begins at puberty and is called menarche. • The menstrual cycle comprises of four phases: menstrual, follicular, ovulatory and luteal phase. 54

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The uterine lining detaches leading to menstruation

e c re t o r y p h a s

or s

l ea

Ovulation

6 7 8 9 10 11

• The rapid rise in plasma LH level, known

as the LH surge leads to final maturation of Graafian follicle. • Follicle ruptures and a secondary oocyte is released on about Day 14. • Shortly after onset of midcycle LH surge, plasma estradiol levels drop and a further rise in plasma progesterone occurs.

• Ovarian follicles begin to enlarge through proliferation of their granulosa cells. • The FSH stimulates ovarian follicle to secrete estrogen, that stimulates the proliferation of the endometrium of the uterine wall. • New blood capillaries develop and the epithelial lining of oviduct develops more cilia. The activity of secretory cells is enhanced. Muscles of the genital tract become more active. Cervix develops mucous strings which form channels for guiding movements of sperms.

Growing follicle

Ovulation

Corpus luteum

Corpus albicans

37°C 36°C Luteinising hormone (LH) Follicle-stimulating hormone (FSH)

Progesterone

Estrogen

Endometrium

Ovarian hormones

Anterior pituitary hormones Body temp. Ovarian cycle

Fig.: Schematic representation of menstrual cycle

Uterine cycle

•

16 15 14 13

Follicular or prolifera tive p

•

25 24 23 22 21 20 19 18 17

•

str

•

Men

27 28 1 2

se ha

• Following ovulation, LH stimulates the remnants of ovulated follicle to develop into corpus luteum, which secretes progesterone and some estradiol. Both LH and progesterone help in further growth and thickening of endometrium. The major change is that the endometrial glands become secretory. The uterine wall becomes ready for nourishing and anchoring blastocyst if fertilisation takes place. Progesterone inhibits uterine movements as well as proliferation of new ovarian follicles. The phase lasts for about 10 days. If the oocyte is not fertilised, corpus luteum activity declines and it degenerates into corpus albicans. With decrease in ovarian hormones, release of GnRH, FSH, and LH occurs due to loss of negative feedback suppression by ovarian hormones. This resumes follicular growth.

It continues usually for 3-5 days. Rapid decrease in estradiol and progesterone (secreted by corpus luteum) level induces changes in endometrium. The blood vessels rupture causing bleeding. The uterine tissue and blood, tissue fluid from the endometrial surface pass out through vaginal opening, constituting menstrual flow.

Beginning of cycle

Menses Follicular phase 0 days

Menses

Luteal phase 14 days Ovulation

28 days

Fig.: Summary of events during a menstrual cycle MT BIOLOGY

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Menopause • It is a phase in woman’s life when ovulation and menstruation stop. During this condition, ovaries fail to respond or may become resistant to FSH. In this case FSH levels are very high and the estrogen levels are very low. It occurs between 45 to 55 years of age (in some individuals, it is between 40 to 50 years). • Since there are no developing follicles, the supply of estrogen and progesterone is reduced. This may lead to temporary depression, hot flushes and other physiological and psychological problems during menopause.

HORMONAL CONTROL OF FEMALE REPRODUCTIVE SYSTEM • The growth, maintenance and functions of female reproductive organs are regulated and controlled by various hormones. Hypothalamus secretes GnRH Stimulates Anterior lobe of pituitary

FSH

• Stimulates corpus

• Stimulates growth of ovarian follicles. • Increases development of oocyte within follicle to complete

luteum to secrete progesterone.

meiosis I to form secondary oocyte.

• Stimulates formation of estrogen. • Increased levels of progesterone inhibits the release of GnRH, which in turn, inhibits the production of FSH, LH and

progesterone.

Disorders of Female Reproductive System

• • • •

Menstrual disorder Dysmenorrhoea is painful menstruation. Menorrhagia is excessive menstruation. Oligomenorrhoea is sparse or infrequent menstruation. Amenorrhoea is absence of menstruation.

Cervical cancer It is relatively slow-growing cancer. Its main risk is that it is unnoticed until it has invaded other tissues. Oophorocytosis (Ovarian cysts) Ovarian cysts are fluid-filled tumors of the ovary. Such cysts sometimes rupture and regress during pregnancy. Ectopic pregnancy It is implantation of embryo at a place other than uterus, generally in the oviduct.

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Breast cancer Breast cancer is rarely seen before the age of thirty. Its incidence increases after menopause.

Infertility Infertility in women is the inability to become pregnant. It may be due to failure to ovulate or some anatomical factors that prevents the union of egg and sperm.

Endometriosis It is the growth of endometrial tissue outside the uterus. Its symptoms include premenstrual pain or unusual menstrual pain.

Oophoritis It is inflammation of ovary, usually caused by an infection.

New MCQs 1. Select the option which correctly fills the given blanks. (i) Fallopian tubes are attached to the ovaries through _______. (ii) _______ cells nourish the developing oocyte and begin to secrete estrogens. (iii) Corpus luteum is filled with _________ coloured lutein pigment. (iv) Ovarian stroma is covered by a layer of connective tissue called _________. (i) (ii) (iii) (iv) (a) isthmus Follicular red cortex (b) fimbriae Granulosa yellow tunica albuginea (c) fimbriae Follicular yellow visceral peritoneum (d) infundibulum Granulosa grey germinal epithelium 2. Match column I with column II and select the correct option. Column I Column II 1. Prolactin P. Secretion of estrogen 2. Oxytocin Q. Milk production 3. FSH R. Ovulation 4. LH S. Milk ejection (a) 1 - S ; 2 - Q ; 3 - R ; 4 - P (b) 1 - Q ; 2 - P ; 3 - R ; 4 - S (c) 1 - S ; 2 - Q ; 3 - P ; 4 - R (d) 1 - Q ; 2 - S ; 3 - P ; 4 - R 3. Read the given statements and select the correct option Statement A : Genetic variations occur during oogenesis. Statement B : Crossing over takes place during meiotic division of primary oocyte. (a) Both statements A and B are correct and B is the correct explanation of A. (b) Both statements A and B are correct but B is not the correct explanation of A. (c) Statement A is correct but statement B is incorrect. (d) Statement A is incorrect but statement B is correct. 4. Refer to the given figure and hints. Identify the correct phases of menstrual cycle with their days.

A C

Cycle begins here

I. II. III. (a)

During C, endometrium breaks down. During A, FSH and estrogen secretion increases. During B, progesterone is secreted. A - Menstrual phase, 1st - 3rd days B - Follicular phase, 5th - 18th days C - Luteal phase, 20th - 28th days (b) A - Luteal phase, 10th - 18th days B - Follicular phase, 20th - 28th days C - Menstrual phase, 1st - 10th days (c) A - Follicular phase, 6th - 13th days B - Luteal phase, 15th - 28th days C - Menstrual phase, 1st - 5th days (d) A - Ovulatory phase, 1st - 5th days B - Luteal phase, 6th - 10th days C - Menstrual phase, 10th - 28th days 5. Which of the following events results in the beginning of ovarian cycle? (a) Sudden decrease in level of progesterone (b) Increased level of estrogen (c) Increased secretion of FSH and LH from anterior pituitary (d) Increased secretion of GnRH from hypothalamus 6. Which of the following consists of haploid number of chromosomes? (a) Oogonia (b) Primary oocyte (c) Secondary oocyte (d) None of these 7. First polar body is formed after (a) mitosis (b) meiosis I (c) meiosis II (d) fertilisation. 8. During oogenesis, oogonium produces (a) two functional eggs (b) two functional eggs and three polar bodies (c) one functional egg and three polar bodies (d) one functional egg and one polar body. 9. Which one of the following is the widest and longest part of oviduct? (a) Infundibulum (b) Isthmus (c) Ampulla (d) Fimbriae MT BIOLOGY

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10. Consider the following statements and select the option stating which ones are true (T) and which ones are false (F). (i) Cessation of menstrual cycle in women is called menopause. (ii) Menstrual cycle is controlled by pituitary as well as ovarian hormones. (iii) Oogenesis begins in childhood and gets completed after fertilisation. (iv) Oogenesis is controlled by the pituitary hormones only. (i) (ii) (iii) (iv) (a) T F T F (b) T T F T (c) F F T T (d) T T F F 11. Choose the incorrectly matched pair. (a) Bartholinâ&#x20AC;&#x2122;s gland - Either side of urethral opening (b) Areola - Pigmented area around the nipple (c) Mammary ampullae - May store milk (d) Glands of Skene - Homologous to male prostate 12. Given flow chart represents the events occurred at the attainment of puberty in human female. Identify the hormones X and Y. Pituitary gland X Development of ovary Y Development of secondary sexual characters

(a) X - Gonadotropin releasing hormone, Y - Progesterone (b) X - Growth hormone, Y - Gonadotropic hormone (c) X - Follicle stimulating hormone, Y - Luteinising hormone (d) X - Follicle stimulating hormone, Y - Estrogen 13. Identify the correct statement. (a) Follicular antrum is present in the secondary follicle. (b) Corona radiata is formed of modified granulosa cells. (c) Degeneration of ovarian follicles is called ovarian atresia. (d) The outermost covering of a mature Graafian follicle is cumulus oophoricus. 14. The thick layer of uterus wall involved in strong uterine movements during parturition is (a) perimetrium (b) myometrium (c) endometrium (d) both (b) and (c). 15. Read the following statements and select the incorrect one. (a) Graafian follicle contains granulosa cells which secrete estrogen. (b) Corpus luteum is formed by the germinal epithelium of the ovary. 58

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Exam Section 1. Changes in GnRH pulse frequency in females is controlled by circulating levels of (a) progesterone only (b) progesterone and inhibin (c) estrogen and progesterone (d) estrogen and inhibin. (NEET Phase-I 2016) 2. What is the inner lining of the uterus called? (a) Cervix (b) Oviduct (c) Endometrium (d) Fimbriae (J & K 2015) 3. Which of the following events is not associated with ovulation in human female? (a) Release of secondary oocyte (b) LH surge (c) Decrease in estradiol (d) Full development of Graafian follicle (AIPMT 2015) 4. The part of Fallopian tube closest to the ovary is (a) infundibulum (b) isthmus (c) ampulla (d) cervix. (J & K 2015) 5. The main function of mammalian corpus luteum is to produce (a) estrogen only (b) progesterone (c) human chorionic gonadotropin (d) relaxin only. (AIPMT 2014) 6. The figure shows a section of human ovary. Select the option which gives the correct identification of either A or B with function/characteristic. A

(a) (b) (c) (d)

B- Corpus luteum - Secretes progesterone A- Tertiary follicle - Forms Graafian follicle B- Corpus luteum - Secretes estrogen A- Primary oocyte - It is in the prophase-I of the meiotic division (NEET - Karnataka 2013)

7. The secretory phase in the human menstrual cycle is also called (a) luteal phase and lasts for about 6 days (b) follicular phase and lasts for about 6 days (c) luteal phase and lasts for about 13 days (d) follicular phase and lasts for about 13 days. (AIPMT Mains 2012)

8. The figure given below depicts a diagrammatic sectional view of the human female reproductive system. Which set of three parts out of I-VI have been correctly identified?

I II

III IV V VI

(a) (b) (c) (d)

(II) Endometrium, (III) Infundibulum, (IV) Fimbriae (III) Infundibulum, (IV) Fimbriae, (v) Cervix (IV) Oviducal funnel, (V) Uterus, (VI) Cervix (I) Perimetrium, (II) Myometrium, (III) Fallopian tube (I) (AIPMT Prelims 2011)

9. The second maturation division of the mammalian ovum occurs (a) shortly after ovulation before the ovum makes entry into the Fallopian tube (b) until after the ovum has been penetrated by a sperm (c) until the nucleus of the sperm has fused with that of the ovum (d) in the Graafian follicle following the first maturation division. (AIPMT Prelims 2010) 10. Which one of the following is the correct matching of the events occurring during menstrual cycle? (a) Proliferative phase : Rapid regeneration of myometrium and maturation of Graafian follicle (b) Secretory phase : Development of corpus luteum and increased secretion of progesterone (c) Menstruation : Breakdown of myometrium and ovum not fertilised (d) Ovulation : LH and FSH attain peak level and sharp fall in the secretion of progesterone (CBSE-PMT 2009) 11. Some important events in the human female reproductive cycle are given below. Arrange the events in a proper sequence. A – Secretion of FSH, B – Growth of corpus luteum, C – Growth of the follicle and oogenesis, D – Ovulation, E – Sudden increase in the levels of LH (a) A → D → C → E → B (b) B → A → C → D → E (c) C → A → D → B → E (d) A → C → E → D → B (Karnataka-PMT 2009) 12. Which hormone level reaches peak during luteal phase of menstrual cycle ? (a) Luteinising hormone (b) Progesterone (c) Follicle stimulating hormone (d) Estrogen (J & K-PMT 2008)

13. In the human female, menstruation can be deferred by the administration of (a) combination of FSH and LH (b) combination of estrogen and progesterone (c) FSH only (d) LH only. (CBSE-PMT 2007) 14. Withdrawal of which of the following hormone is the immediate cause of menstruation? (a) Progesterone (b) Estrogen (c) FSH (d) FSH-RH (CBSE-PMT 2006) 15. A human female reaches menopause around the age of (a) 50 years (b) 15 years (c) 70 years (d) 25 years. (Karnataka-PMT 2000)

Assertion & Reason The following questions consist of two statements each : assertion (A) and reason (R). To answer these questions, mark the correct alternative as directed below: (a) If both A and R are true and R is the correct explanation of A. (b) If both A and R are true but R is not the correct explanation of A. (c) If A is true but R is false. (d) If both A and R are false. 1. Assertion : 1st mitotic division in primary oocytes results in the formation of two equal sized cells.

Reason : These cells are equally functional. 2. Assertion : The main function of mammary glands is lactation. Reason : Mammary glands develop under the influence of prolactin and oxytocin. 3. Assertion : Menstrual cyclical changes occur in oviducts and uterus of female.

Reason : Oviducts and uterus are sites of fertilisation.

ANSWER KEY

MPP-1 CLASS XII 1. 6. 11. 16. 21. 26. 31. 36.

(a) (c) (b) (c) (d) (d) (b) (a)

2. 7. 12. 17. 22. 27. 32. 37.

(a) (a) (b) (b) (b) (d) (d) (d)

3. 8. 13. 18. 23. 28. 33. 38.

(a) (b) (a) (c) (b) (d) (a) (c)

MT BIOLOGY

4. 9. 14. 19. 24. 29. 34. 39.

(b) (b) (d) (a) (d) (a) (d) (c)

TODAY | MAY ‘17

5. 10. 15. 20. 25. 30. 35. 40.

4. Assertion : Germinal epithelial cells of ovary produce oogonia. Reason : Oogonia are formed during fetal development. 5. Assertion : The uterus and the vagina gradually become atrophic at the age of 45 to 55 in women.

Reason : Decreased level of estrogen and progesterone leads to menopause.

Short Answer Type Questions 1. Fill in the blanks. (i) Degenerated corpus luteum is called______ . (ii) Formation of polar bodies help in retention of sufficient amount of _______ in the ovum. (iii) During ovulation, concentration of ______ reaches its peak in blood. 2. In which phase of mestrual cycle, formation of corpus luteum takes place? Also mention the name of its degenerated stage. 3. Write a brief note on the hormonal control of female reproductive system. 4. Draw a labelled diagram of human female reproductive system.

ANSWER

KEY

New MCQs 1.

(b)

(d)

(a)

(c)

(b)

(c)

10. (d)

14. (b)

15. (b)

11. (a)

12. (d)

13. (b)

(a)

Exam Section 1.

(a)

(c)

(a)

(c)

(b)

10. (b)

14. (a)

15. (a)

11. (d)

12. (b)

13. (b)

(b)

Assertion & Reason 1.

(d)

(c)

(d)

(b)

(a)

Short Answer Type Questions

of menstrual cycle in females. This phase usually includes cycle days 15 to 28 in a 28 days cycle. Followed by the ovulation, the remaining cells of ovarian, follicles are developed as corpus luteum under the influence of LH. It secrete progesterone to support pregnancy. However, in the absence of fertilisation, the corpus luteum degenerates. The degenerated part of corpus luteum is called corpus albicans. 3. The growth, maintenance and functions of the female reproductive organs are controlled by several hormones. GnRH is secreted by the hypothalamus which stimulates the anterior lobe of pituitary gland to secrete LH and FSH. FSH stimulates the growth of the ovarian follicles and increases the development of oocyte within the follicle to complete the meiosis I to form secondary oocyte. It also stimulates the formation of estrogen. LH stimulates the corpus luteum to secrete progesterone. The rising level of progesterone inhibits the release of GnRH, hence inhibits the production of FSH, LH and progesterone. Females attain puberty when pituitary gland starts producing of follicle-stimulating hormone (FSH). It induces the development of ovaries, which in turn produce the hormone estrogen. This hormone is responsible for the development of the female secondary sexual characters, like change in voice, development of external genitalia, breast, body hair, pubic hair, widening of the pelvis and deposits of fat in thighs, buttocks, face, etc. 4. Diagrammatic representation of female reproductive system is as follows : Fallopian tube Broad Ovarian Uterine Uterine Uterine ligament ligament fundus cavity part

Wall of uterus

Ovary Perimetrium Myometrium Endometrium

Uterine body

Cervical canal Vagina

Vaginal opening

(ii) cytoplasm (iii) leutinising hormone 2. Corpus luteum is formed during the luteal or secretory phase MT BIOLOGY

Fimbriae

Cervix of uterus

Internal OS External OS

1. (i) corpus albicans

Infundibulum Isthmus Ampulla

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Hymen



Class XII

Human Health and Diseases

– 5 4 8 J&K

–

– 3

1 5

– –

Kerala

K.CET

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1 3

4 12

2016 2015

4 2

2014

6 1

–

AIIMS

Toxin secretion Many microbes produce powerful poisons, called toxins which cause diseases.

AMU

Tissue damage The bacteria responsible for tuberculosis, damage cells and cause lesions in the lungs. The bacteria that cause meningitis attack the protective membranes, called meninges, covering the brain.

Pathogens cause diseases in two ways

2013

•

2012

•

Analysis of various PMTs from 2012-2016

•

dysfunction, distress, social problems, or death to the person afflicted, or similar problems for those in contact with the person. The term disease is used to refer specifically to infectious diseases that result from the presence of pathogenic microbial agents, such as viruses, bacteria, fungi, protozoa, multicellular organisms and aberrant proteins known as prions. A symptom is a sensation or change in health experienced by a patient e.g., fatigue, pain, nausea, etc. Pathogen (pathos-disease, gen-causing) refers to an organism that causes certain diseases in animals and plants, e.g., bacteria, virus, fungi, etc. Vectors are the carriers that do not cause disease themselves but transmit the disease causing pathogens from infected person to a healthy person, e.g., female Anopheles mosquito is the vector of malarial pathogen, Plasmodium.

AIPMT/NEET

often construed as a medical condition associated with specific symptoms and signs.

• In humans, “disease” is often used more broadly to refer to any condition that causes pain,

• Health is a state of optimum physical fitness, mental maturity and social well being. • A disease is a particular abnormal, pathological condition that affects part or all of an organism. It is

Types of toxins Exotoxins These are released as soon as they are produced. The diseases brought about by exotoxins include tetanus, diphtheria and botulism (food poisoning).

Endotoxins These are retained in the bacterial cells and released when bacteria die and disintegrate. The diseases caused by endotoxins include typhoid fever, cholera, bubonic plague and dysentery.

TYPES OF DISEASES Congenital Diseases • Inborn diseases, i.e., diseases with which a person is born. Hereditary/ Genetic diseases These are caused either due to single gene mutation e.g., albinism, haemophilia, colourblindness, etc., or chromosomal aberrations e.g., Down’s syndrome, Turner’s syndrome, etc.

Acquired Diseases • Diseases which are contracted after birth due to various factors like infection, degeneration, diet, etc.

Diseases due to environmental factors These are caused due to influence during the embryonic development, e.g., cleft palate or harelip, etc.

Communicable/ Infectious diseases These disease are caused by pathogens and can spread from infected person to a healthy one.

Contagious diseases Pathogen is transferred to a healthy person through contact, e.g., ringworm.

Deficiency diseases These are produced due to deficiency of nutrients, m i n e r a l s, v i t a m i n s and hormones, e.g., kawashiorkor, beriberi, goitre, etc.

Mental disorders These include emotional instability, behavioural dysregulation, cognitive dysfunction or impairment, e.g., depression, anxiety, schizophrenia, etc.

Allergies These are caused when body becomes hypersensitive to c e r t a i n f o r e i g n substances, e.g., rhinitis.

Non-communicable/ Non-infectious diseases These diseases remain confined to the persons who develop them and do not spread in others.

Non-contagious diseases Pathogen spreads through a vector or vehicle, blood, serum, food, etc.

Organic diseases Th e s e a r e c a u s e d due to physical or physiological changes of some tissue or organ of the body, e.g., heart diseases, epilepsy, etc.

Cancers These are caused by an uncontrolled and abnormal division of cells which destroy surrounding tissues, e.g., breast cancer, lung cancer, etc.

Addictions These are due to drug abuse, alcohol or tobacco, e.g., liver cirrhosis, infertility, etc.

Flow chart : Classification of Diseases

Transmission of Diseases • There are different ways through which diseases can be transmitted. • Two main types of modes of transmission of diseases are :

(i) Direct transmission : • The pathogens are carried directly to the human body without intermediate agents. Various ways of direct transmission are Direct physical contact E.g., Chicken pox

Droplet contact By sneezing, coughing, spitting and talking, e.g., diphtheria, influenza, measles

Contact with soil E.g., Bacteria responsible for tetanus

Through placenta E.g., German measles and syphilis

Animal bites E.g., Rabies

(ii) Indirect transmission : • The pathogens are carried through some intermediate agents. Various ways of indirect transmission are Arthropod vectors E.g., Typhoid, cholera by housefly

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Vehicle borne methods E.g., AIDS, Hepatitis B by blood

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Air borne methods E.g., Epidemic typhus

Fomite borne methods E.g., Influenza

Human carriers E.g., Diphtheria, typhoid

COMMUNICABLE DISEASES • These are classified into nine types according to the nature of

pathogen, i.e., the disease causing agent.

Viral Diseases Viral hepatitis • Viral hepatitis is commonly called jaundice. • In early stage, the liver is enlarged and congested. In later stage, the liver becomes smaller, yellowish or greenish. • The symptoms in early phase include – fever, anorexia, nausea, vomiting, epigastric discomfort, pain in muscles and joints. • The urine is dark in colour. Leukopenia (reduction in the number of WBCs) is followed by lymphocytosis (increase in the number of lymphocytes). Splenic enlargement is sometimes present. Table: Other viral diseases Disease

Pathogen

Mode of transmission/ Incubation period

Symptoms

Prevention

Dengue fever

Flavi-ribo virus

By bite of Aedes aegypti mosquito/3-8 days

Fever, headache, muscles and joint Eliminating mosquito breeding pains, rashes, nausea, vomiting, places and applying mosquito excessive thirst, bleeding from nose, repellents mouth, gums

Common cold Rhino virus

Droplet contact/ 3-7 days

Nasal congestion, running nose, Washing hands frequently and sneezing, sore throat, cough, fever, using face masks headache

Mumps

Paramyxo virus

Droplet contact/ 7-18 days

Fever, painful swelling of parotid Avoiding contact with the sick; MMR vaccine is available glands

Measles

Rubeola virus

Droplet contact/ 8-15 days

Fever, rash, itching, inflammation of Same as that of mumps respiratory passage

Chicken pox

Varicella zoster virus

Direct contact and Fever, rash which changes into Scabs should be collected and droplet contact/ vesicles, pustules and then brown burnt, soiled articles should be 14-21 days scab which falls off washed and boiled. Vaccine is available

Smallpox (Eradicated from earth)

Variola virus

Direct contact and droplet contact/ 12 days

High fever, chill, headache, vomiting, Same as that of chickenpox rash that turn into scabs that fall off

Poliomyelitis

Polio virus

Contaminated food and water/ 7-14 days

Stiffness of neck, paralysis of skeletal Avoiding contaminated food muscles, fever, headache, pain and water. Salk vaccine and OPV vaccine available

Swine flu

Swine influenza (H1N1) viruses

Droplet contact

Fever, cough, bodyaches, headache, Avoiding close contact with the chills sick. Vaccine is available

SARS (Severe Corona virus Acute Respiratory Syndrome)

Droplet contact/ 2-7 days

Fever, chills, muscleache, cough, Avoiding contact with the sick dizziness, running nose, vomiting, diarrhoea

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Bacterial Diseases Typhoid • Typhoid is a common bacterial disease caused by a rod-like bacterium, Salmonella typhi, which is commonly found in the intestine of man. Mode of transmission • Typhoid spreads via faecal oral route, i.e., through food and water contaminated with faeces of the patient. House flies may carry the pathogens from the faeces to the food, milk and water. • Incubation period varies from 1-3 weeks (average 2 weeks). Symptoms • This disease is characterised by the inflammation of ileum and colon, enlargement of liver and spleen, abdominal pain, pea-soup diarrhoea which may become haemorrhagic, constant fever, extreme weakness, vomiting, rash causing rose spots on the upper abdomen and sore throat. • Typhoid is diagnosed by Widal test. Prevention and Treatment Isolation and hygienic disposal of faeces

Proper sewage treatment

Purification of water supplies

Reduction in contamination of food by personal hygiene and control of flies

Giving TAB vaccine which provide immunity for about 3 years

Antibiotics like ciprofloxacin and chloramphenicol

Anthrax • Anthrax is an acute infectious disease caused by air-borne, spore-forming, rod-like, non-motile bacterium, Bacillus anthracis. • Anthrax spores can be produced in a dry form which can be stored as particles that can be used in biological warfare. Mode of transmission • Infected animals shed a large number of bacilli (bacteria) in the discharges from the mouth, nose and rectum which sporulate in the soil. These spores act as source of infection. • It requires thousands of spores to cause human infection. Anthrax does not spread from human to human. Symptoms • Initial symptoms resemble those of common cold. Later there is difficulty in breathing, cough, fever, fast pulse and cardiovascular collapse. • If left untreated, anthrax in all forms can lead to septicemia and death. Prevention and treatment • The only known effective prevention against anthrax is the anthrax vaccine, which was developed from an attenuated strain of B. anthracis. • A suitable antibiotic like ciprofloxacin is quite effective, particularly if used in the initial stages of disease. But in cattle, ciprofloxacin may be effective only in chronic condition. Table:

Other bacterial diseases Disease Pathogen

1. Cholera

Vibrio cholerae

2. Diarrhoeal diseases

E.coli, Shigella, Campylobacter, Salmonella, Clostridium

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Mode of transmission/ Incubation period Contaminated food and drinks / 2 - 3 days Contaminated food and drinks/variable period

Symptoms

Control measures/ Treatment

Vomiting, dehydration, Proper sanitation/ORS, muscular cramps tetracycline Frequent stools with Proper sanitation /ORS blood, dehydration, low blood pressure

Pneumonia

Streptococcus pneumoniae, Direct contact / Haemophilus influenzae 1 - 3 days

Cough, fever, pain in the PCV13 vaccine / lungs Erythromycin, tetracycline

Diphtheria

Corynebacterium diphtheriae

Droplet infection/ 2-5 days

Fever, sore throat

DPT vaccine / Erythromycin

Whooping cough or pertussis

Bordetella pertussis

Direct contact / 10 - 16 days

Cough, breathlessness and vomiting

DPT vaccine/Erythromycin

Tuberculosis Mycobacterium tuberculosis Droplet infection and Constant cough, pain contaminated food and in chest, loss of weight drinks / 3 - 6 weeks and appetite

Tetanus (Lock jaw)

Clostridium tetani

Spores enter the wounds Painful muscular / 3 - 25 days spasms, fever, lock jaw

DPT / Antitetanus serum (ATS), tetanus toxoid

Plague (Black death)

Pasteurella/Yersinia pestis

Bite of infected rat flea Xenopsylla cheopis / 2 - 6 days

Painful buboes, fever, haemorrhages

Streptomycin, oral tetracycline, antiplague vaccine

Leprosy (Hansen’s disease)

Mycobacterium leprae

Prolonged direct contact / 2 - 5 years

Infection of skin, wasting Rifampicin, dapsone, of body parts, deformities clofazimine of fingers, toes, hypopigmentation

BCG/Streptomycin, PAS rifampicin

Protozoan Diseases • Protozoans are diverse group of eukaryotic, unicellular organisms. • Human diseases caused by protozoa are relatively few, but are individually of devastating consequences.

Malaria • Malaria is caused by a digenetic (have two hosts to complete its life cycle) protozoan parasite known as Plasmodium. • The primary host is female Anopheles mosquito and secondary host is man. • Sir Ronald Ross established that malarial parasite is transmitted by the bite of a female Anopheles mosquito for which he got

Nobel Prize in 1902.

Mode of transmission • The malarial parasite, Plasmodium enters the human body as sporozoites (infective stage) through the bite of infected female Anopheles mosquito. • There are four species of Plasmodium which causes four main types of malaria in human.

Types of malaria

Benign tertian malaria

• Caused by Plasmodium vivax. • Fever recurs after every 48 hours. • Incubation period is about 14 days.

Quartan malaria

• Caused by P. malariae. • Fever appears after every 72 hours.

• Incubation period is 28-30 days.

Malignant tertian malaria

Mild tertian malaria

• Caused by P. falciparum. • Caused by P. ovale. • Fever recurs after every 48 • Fever recurs in every 48 hours.

• Incubation period is 12 days.

hours.

• Incubation period is 14 days.

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MOSQUITO (PRIMARY HOST)

Mature infective stages (sporozoites) escape from intestine and migrate to the mosquito salivary glands

HUMAN (SECONDARY HOST)

Ruptured Liver schizont

Erythrocyte

Hepatic schizont

Sporozoites reach the liver through blood

Salivary glands

The parasite reproduces asexually in liver cells, bursting the cell and releasing into the blood.

Merozoites

Early trophozoite (ring stage)

Ruptured schizont Blood stage

Infected hepatocyte

Schizont

Sporozoites

Mature trophozoite

Oocyst ruptures to release sporozoite. Fertilisation and development take place in the mosquito’s stomach.

Ookinete attaches to gut and becomes oocyst Mid-gut Ookinete Fertilised female gamete Female mosquito becomes zygote which takes up gametocytes further forms ookinete. with blood meal.

Parasites reproduce asexually in red blood cells, bursting the red blood cells and causing cycles of fever and other symptoms. Released parasites infect new red blood cells.

Sexual stage (gametocytes) develop in red blood cells.

Fig.: Life cycle of Plasmodium Symptoms • Malaria is characterised by fever at intervals, each attack of malaria fever shows three successive stages: (i) Cold stage - At the onset of fever, patient suffers a severe shaking chill and needs to be covered with huge pile of blankets. It lasts for 20 minutes to one hour. (ii) Hot stage - As chill subsides, the body temperature rises as high as 41-106°F. It lasts for 1-4 hours. (iii) Sweating stage - As the temperature drops, patients sweats profusely. Finally the fever comes down and temperature becomes normal. • Malaria is also accompanied by nausea, headache, laziness and muscular pain. It also results in anaemia and splenomegaly.

Prevention and Treatment Spraying DDT, BHC and other insecticides

Fitting doors and windows with wire nets

Table: Other protozoan diseases Disease Pathogen

Amoebiasis

Entamoeba histolytica

Giardiasis

Giardia intestinalis

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Using mosquito nets and repellants

Use of drugs like chloroquine, quinine, primaquine, etc.

Mode of transmission/ Symptoms Incubation period Faecal - oral route, sexual Abdominal pain, contact, vectors, e.g.,flies. diarrhoea, blood in / 2-4 weeks faeces, passing out of mucus Contaminated food and Epigastric pain, water / 1-3 weeks headache, diarrhoea

Control measures / Treatment Sanitation, protection of food from flies. Emetine, stremetine and metronidazole Clean food and water/ Metronidazole, tinidazole

Trypanosomiasis or African sleeping sickness Kala-azar or Dum-dum fever

Trypanosoma gambiense

Leishmania donovani

Biting of tse tse fly (Glossina sp.)/ Weeks or months

Swelling of lymphatic glands, recurrent fever, anaemia, patient falls asleep Bite of sandfly High fever, spleen Phlebotomus argentipes / enlargement, anaemia, 3-6 months darkening of skin

Pentamidine, atoxyl, tryparsamide, germanin

Sodium antimony tartrate, glyconate, urea stebamine, neostibosan

Helminthic Diseases • Helminths are animals that belong to the Phylum Platyhelminthes (flatworms) and Nematoda (roundworms). • Many parasitic forms of this group, popularly known as parasitic worms are endoparasites of gut and blood in human body

and cause various diseases called as helminthiasis. Table: Helminthic diseases Disease 1. Taeniasis

2. Ascariasis

Pathogen Taenia solium (Pork tapeworm), Taenia saginata (Beef tapeworm) Ascaris lumbricoides

Mode of transmission

Raw or under- cooked pork Abdominal pain, nausea, or beef anaemia, indigestion, epilepsy

Prevention / Treatment Pork or beef to be cooked properly before eating / Camoquin and atabrin

Contaminated fruits, vegetables, food or water, etc., containing Ascaris eggs

Muscular pain, fever, anaemia, blockage of intestinal passage

Preventing exposure to unhygienic conditions/ Chenopodium oil, tetrachloroethylene

Swelling of feet, legs, thighs, scrotal sacs, breast

Take precautions against mosquito bites/ Albendazole, hetrazan,diethyl carbamazine (DEC)

3. Filariasis (Elephantiasis)

Wuchereria bancrofti, Bite of Culex mosquito W. malayi

4. Ancylostomiasis

Ancylostoma duodenale

Symptoms

Juveniles penetrate through Gastrointestinal skin of hands and feet disturbances, anaemia, nervous disorders.

Proper sanitation and hygiene/ Tetrachloroethylene and carbon tetrachloride

Fungal Diseases • The fungal diseases of man are either mycoses (caused by infection of fungi) or toxicoses (caused by toxic fungal metabolites).

Table : Fungal disease Disease Ringworm (Tinea)

Pathogen Microsporum

Mode of transmission/ Incubation period Direct contact or by soil

Symptoms Infect skin, hair and nails

Control measure/ Treatment Drugs like griseofulvin and miconazole inhibit infection

NON-COMMUNICABLE DISEASES • These diseases are not transmitted from infected persons to healthy persons. • Some of the non-communicable diseases are discussed below:

– Diabetes mellitus or hyperglycemia is the most common endocrine disorder of the pancreas which is caused when either insulin is produced insufficiently (insulin dependent diabetes mellitus) or becomes non functional (non-insulin dependent diabetes mellitus). In both disorders, the blood glucose concentration is elevated above the normal range. Glucose is excreted in urine, resulting in excessive urination and dehydration of body tissues. MT BIOLOGY

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– Cardiovascular diseases are those diseases that affect the blood vessels and heart, for e.g., (i) Arteriosclerosis - Hardening and loss of elasticity of the arteries, causes high blood pressure. (ii) Atherosclerosis - Lumpy thickness develops on the inner walls of arteries that prevent dilation of arteries. (iii) Hypertension or high blood pressure - Arterial pressure exceeding 120/80 mmHg; can result in heart failure, kidney damage, etc. (iv) Myocardial infraction - Clot formation in the lumen of coronary artery, results in “heart attack”. – Cerebrovascular accident (CVA) or stroke is the sudden interruption of blood flow to a portion of the brain due to a blockage or rupture of a cerebral blood vessel. Thus, the brain cells do not get sufficient oxygen and glucose. This can cause paralysis, loss of speech, etc.

IMMUNITY • Immunity is the ability of the body to protect against all types of foreign bodies like bacteria, virus, toxic substances, etc., which

enter the body. It is also called disease resistance. The lack of immunity is known as susceptibility. • The study of body’s defence mechanism against pathogens is called immunology. • Edward Jenner (1749 - 1823) is known as the Father of Immunology. • Antigens are substances which when introduced into the body, stimulate the production of antibodies.

Types of Immunity

Innate/Inborn/Non-specific defence mechanism. It is inherited since birth and consists of four types of barriers against the entry of foreign agents into the body.

(i) Physical barriers - Skin, mucous membrane. (ii) Physiological barriers - Bile, cerumen, urine, nasal hair, etc. (iii) Cellular barriers - WBCs, natural killer cells, PMNL-neutrophils, etc. (iv) Cytokine barriers - Interferons, interleukines.

Acquired/Adaptive/Specific defence mechanism. It is acquired after birth during one’s lifetime. It is specific and mediated by antibodies that make the antigen harmless. Unique features of acquired immunity are specificity, diversity, discrimination between self and non-self and memory.

Active immunity

Passive immunity

Person’s own cells produce antibodies in response to infection or vaccination; is slow and takes time to form antibodies, long lasting and harmless.

Develop when readymade antibodies are directly injected into a person to protect the body against foreign agents; gives immediate relief; not long lasting.

Flow chart : Types of Immunity

Components of Acquired Immunity • It has two components:

1. Antibody mediated immune system (AMIS) or humoral immunity • It consists of antibodies that circulate in the body fluids like blood plasma and lymph. Antigen enters body • B-lymphocytes or B-cells produce antibodies that regulate antibody mediated or humoral immunity. Other B-cells “remember” • T-lymphocytes do not secrete antibodies but help B lymphocytes to produce Some B-cells become plasma cells the antigen i.e., memory cells them. • B-cells give rise to: Plasma cells produce Memory cells cause the – Plasma cells (Effector B-cells) : The antigen specific T-cells antibodies production of new plasma cells stimulate specific B-lymphocytes to multiply rapidly, forming clone of when same antigen again enters body. plasma cells. Antibody reacts with antigen – Memory B-cells : Some of the activated B cells do not differentiate into plasma cells but rather remain dormant as memory B-cells until Flow chart: Functioning of Humoral Immunity activated once again by a renewed attack of the same antigen. 68

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2. Cellular immunity or cell-mediated immune system or T-cell immunity (CMIS) • T lymphocytes or T-cells are produced in the bone marrow and mature in thymus. Types of T-cells Other T-cells “remember” the antigen i.e., memory cells. • Cytotoxic or killer T-cells : Directly attack and destroy antigens by secreting a protein perforin. • Suppressor T-cells : Keep a check on entire immune system from attacking the body’s own cells. • Helper T-cells : Stimulate the B-cells to produce antibodies. They form protein mediators called lymphokines. Flow chart : Functioning of Cell-mediated Immunity • Memory cells : Sensitised T-cells retain memory of antigen specificity for future, sometimes lifelong. They proliferate and differentiate into all types of T-cells.

Immune Response

Antibody concentration in serum

• The specific reactivity induced in a host by an antigenic stimulus is known as the immune response.

Primary immune response Reaction of body’s immune system to the first attack of microbe (antigen). It takes longer time to establish immunity and declines rapidly.

Secondary immune response/ Booster response Reaction of the body’s immune system to any subsequent infection of the same microbe antigen. It is more rapid, intense response that lasts for a longer period. Antibody

Total antibody

Plateau IgG IgG

Decline

IgM

Lag period 5 days

15 days

10 days

15 days

Fig.: Primary vs Secondary immune responses

Immune System • The human immune system comprises of lymphoid organs, tissue cells and soluble molecules such as antibodies. • Lymphoid organs are of two types : Primary lymphoid organs where B-and T-lymphocytes mature and acquire antigen-

specific receptors such as bone marrow and thymus and secondary lymphoid organs where mature lymphocytes undergo proliferation and differentiation such as spleen, lymph nodes, tonsils, etc. • Antigen Presenting Cells (APCs) - APCs are the cells that engulf antigens and present fragments to T-cells. E.g., marophages, dendritic cells and B cells.

Antibodies • Antibodies are immunoglobulins (Igs) which are produced in response to antigenic stimulation. • All antibodies are immunoglobulins but all immunoglobulins are not antibodies. • Antibodies are produced by B-lymphocytes and plasma cells. The mature plasma cells produce antibodies which direct antibody mediated immunity. MT BIOLOGY

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Antigen-binding site N

N VH

Antigen-binding site N

Heavy chain (H) VL

CH1

Light chain (L) CL C

S–

S–S S–S

S–

Hinge CH1 region

CH2

Variable regions (V)

CH2 Constant regions (C)

Interchain CH3 disulfide bonds

CH3 C

Fig.: Structure of antibody molecule

Types of Immunoglobulins IgG

• Most abundant, found in blood, lymph and intestine.

• Predominant antibody in the secondary response. • Only antibody to cross the placenta. • Opsonizes i.e., enhance phagocytosis, neutralises toxins,fixes complement.

IgA • Second most abundant antibody. • Found in body secretions including saliva and tears. • Available in colostrum (first milk secreted by a mother).

• Localised protection in external secretions. IgM

• Largest antibody. • Produced early in the primary response. • Most efficient in agglutination, complement fixation.

IgD

• Functions as antigen receptor on surface of B cells. • Present on surface of B-cells and in blood and lymph.

• • • • 70

IgE Least abundant. Bound to mast cells and basophils throughout the body. Mediate immediate hypersensitivity reactions. Involved in allergic reactions.

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VACCINATION AND IMMUNISATION • Vaccine (L. vacca = cow) is a preparation/suspension or extract of dead/attenuated (weakened) germs of a disease which on

inoculation (injection) into a healthy person provides temporary/permanent active/passive immunity by inducing antibodies formation. • The process of introducing a vaccine into an individual to provide protection against a disease is called vaccination. Types of Vaccines

First generation vaccines

Third generation vaccines

Second generation vaccines

Live attenuated Inactivated vaccines Subunit vaccines Dead or nonIsolated antigens vaccines replicating form of that best stimulate Prepared from pathogen, requires the immune system, (weakened) higher doses or e.g., Hepatitis-B, strains devoid of boosters, e.g., influenza. pathogenicity e.g., influenza, cholera, measles, rubella, polio. yellow fever.

Toxoid vaccines Isolated deactivated toxins (toxoids) used to induce immune response, e.g., tetanus, diphtheria.

DNA vaccines Piece of DNA (plasmid) genetically engineered to produce specific antigens. Experimental: veterinary use.

Recombinant vector vaccines Harmless vector expresses antigens stimulating immune response. Experimental : wide range targets.

Conjugate vaccines Type of subunit vaccine, antigen combined with a carrier protein. Flow chart : Types of Vaccines

• Immunisation is the process by which the body produces antibodies against the vaccine preventable diseases through

administration of specific vaccines.

ORGAN TRANSPLANT • Transplantation involves the removal of damaged/injured tissues or organs from the body of a person and their substitution by

similar tissues/organs from a donor. • Tissue matching and blood group matching are essential before undertaking any graft/transplant. Sometimes, the immune system

may reject the transplanted organ by recognising its protein as foreign. Therefore, patient has to take immuno-suppressants (drugs) to prevent organ rejection throughout the life. • The success of tissue and organ transplants depends on the donor’s and recipient’s human leucocyte antigens (HLA) encoded by the HLA genes. The genes for the HLA proteins are clustered in the major histocompatibility complex (MHC), located on the short arm of chromosome 6. Autograft It is grafting of one’s own tissue to another part of the body, e.g., skin graft. It is most successful transplantation.

Isograft It is transplantation from a twin brother or sister, i.e., donor and recipient are genetically identical.

Types of Organ Transplantation Allograft It is transplantation between individuals of same species, but with different genetic background.

Xenograft It is transplantation between animals of different species.

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DISORDERS OF IMMUNE SYSTEM Hypersensitivity (Allergy) • • • • • •

Hypersensitivity or allergy is an exaggerated immune response to common antigens, called allergens. Allergy is due to the release of chemicals like histamine and serotonin from the mast cells. Common examples of allergens are mites in dust, pollens, animal dander, etc. Symptoms of allergic reactions include sneezing, watery eyes, running nose and difficulty in breathing. The use of drugs such as antihistamines, adrenaline and steroids quickly reduce the symptoms of allergy. Common examples of allergy are hay fever and asthma.

Autoimmunity • Autoimmunity refers to abnormal immune responses in which the immune system fails to properly distinguish between self and

non-self and attacks self body proteins. • When the cells act as antigens in the same body, they are called autoantigens. • Some of the examples of autoimmune disorders are Grave’s disease, Rheumatic fever, Myasthenia gravis, Pernicious anaemia, etc.

Immunodeficiency Diseases • Immunodeficiencies occur when one or more of the components of the immune system are inactive due to gene mutations,

infections, malnutrition or accident. • A person suffering from an immunodeficiency disease is liable to suffer from diseases which normally would not occur (opportunistic diseases). • SCID and AIDS are two common immunodeficiency diseases. Severe Combined Immuno Deficiency or SCID • It occurs due to defect in the specialised white blood cells (B and T-cells) that represents a group of rare, sometimes fatal, congenital disorders characterised by little or no immune response. Acquired Immuno Deficiency Syndrome or AIDS • AIDS is a disorder of cell-mediated immune system of the body. There is a reduction in the number of helper T cells which stimulate antibody production by B-cells. • This results in the loss of natural defence against viral infections. • The infection by human immuno-deficiency virus (HIV) causes AIDS. • The incubation period of AIDS ranges between 6 months to 10 years.

Infection by HIV (i) Infection : Virus enters the body of a person and reaches macrophages (cells of immune system). (ii) Reverse transcription : The viral RNA is converted to viral DNA with the help of reverse transcriptase enzyme. (iii) Integration : Viral DNA is incorporated into the host cell’s DNA and gets replicated. (iv) Multiplication : The viral DNA replicates along with infected host cell. Thus, the infected macrophages act as HIV factory. (v) Assembly of virus : The viral proteins formed are assembled to form new viral particles which are released from the infected cell. They mature and target T-cells of body (destroy them). (vi) Since the number of helper T lymphocytes decrease in the body, the person becomes susceptible to infections of bacteria, viruses, fungi and even parasites like Toxoplasma. (vii) The patient gets immune deficient and he/she is unable to protect himself/herself against these infections. 72

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• Symptoms of HIV infection include fever, lethargy, pharyngitis, nausea, headache, rashes, etc. • For prevention, one should avoid sharing needles, syringes and should have safe sex. • Although there is no cure for AIDS, use of certain drugs can prolong the life of AIDS patient. Use of contaminated needles and syringes to inject drugs or vaccines. Sexual intercourse with an infected partner without a condom.

Use of contaminated razors. Use of contaminated needles for boring pinnae.

Transmission of AIDS virus

Organ transplantation.

Artificial insemination.

Transfusion of infected blood. From infected mother to child through placenta.

Cancer • Cancer is an abnormal and uncontrolled proliferation of cells without any differentiation. • Due to uncontrolled divisions, an abnormal growth called tumor occurs. • Tumor or neoplasm is any abnormal swelling, lump or mass in the body. Tumor is of two types : Benign and malignant. Benign

tumor remains confined to the site of origin and does not spread to other body parts. Malignant tumors spread to distant sites through body fluids to develop secondary tumor, by the process called metastasis. Types of Cancer Carcinomas

• Mainly derived from epithelial cells. • E.g., cervical (cervix is part of uterus) cancer, breast cancer, skin cancer, lung cancer, stomach cancer, etc.

Melanoma

• Cancer of the pigment producing cells especially in the skin (melanocytes). Germ cell tumor

Leukemias • Commonly called as blood cancers. • Result from excessive formation of WBCs in the bone marrow and lymphatic nodes. Sarcomas • Derived from mesodermal cells, these cancers are located in connective and muscular tissues. • Include the cancers of bones, cartilages, tendons, adipose tissue, lymphoid tissue and muscles.

• Tumor derived from totipotent cells, found in adults, most often in the testes and ovaries. Blastic tumor

• Tumor resembles an immature or embryonic tissue. Many of these tumors are most common in children. Myeloma • Cancer of plasma cells (B-lymphocytes) which are immune system cells in bone marrow that produce antibodies.

Causes of cancer • Chemical and physical agents that can cause cancer are called carcinogens. Carcinogens fall into three basic categories:

(i) Oncogenic transformations: They are carcinogens which bring about changes in genetic material, e.g., radiations (X-rays, cosmic rays, UV rays etc.) and chemicals. (ii) Tumor promoters: They promote proliferation of cells which have undergone oncogenic transformation, e.g., some growth factors, hormones etc.

Table : Carcinogens and organs affected Carcinogens (i) Soot (ii) Coal tar (3, 4-benzopyrene) (iii) Cigarette smoke (N-nitrosodimethylene) (iv) Cadmium oxide MT BIOLOGY

Organs affected Skin, lungs Skin, lungs Lungs Prostate gland TODAY | MAY ‘17

(iii) Tumor viruses: Some viruses are known to be involved in oncogenic transformations.

Possible symptoms of cancer (i) A lump or hard area in the breast. (ii) Unexplained low-grade fever. (iii) Unexplained loss of weight. (iv) Non-injury bleeding from the surface of the skin, mouth or any other opening of the body. (v) Bleeding in vagina at times other than the menstruation.

Treatment • The common approaches for treatment of cancer are surgery, radiation therapy, chemotherapy and immunotherapy.

ALCOHOL AND DRUG ADDICTION • Alcohol refers to ethyl alcohol or ethanol (C2H5OH) manufactured by fermentation of sugars. • Drinking of excessive alcohol that impairs one’s physical, physiological and psychological functions, refers to alcohol abuse.

The dependence or addiction of alcohol is called alcoholism and the addict is termed as alcoholic. WHO declared in 1964 that alcoholism is disease. Problems caused by alcohol Social problems • These include absence from work, unemployment, marital (marriage) tensions, child abuse, financial difficulties and problems with law, including violence and traffic offences.

Psychological problems • Heavy drinking causes depression. Suicide attempt is much common in alcoholics than in the rest of society. • Sexual relationship is usually deteriorated because of impotence or rejection by the partner.

Physical problems • These are variable and can affect virtually any organ in the body.

• Drug addiction or abuse can be defined as intake of drugs for purpose other than clinical use, in amount, concentration or

frequency that impairs physical, physiological and psychological functions of the body. The drugs, which are commonly abused are opioids, coca alkaloids and cannabinoids.

Habituating Drugs

Psychotropic drugs

Psychedelic drugs

Mood altering drugs that affect behaviour and mental activity. Includes tranquilisers, sedatives, hypnotics, opioids and stimulants.

Drugs change one’s behaviour, thoughts, feelings and perceptions without any actual sensory stimulus. Includes LSD, mescaline, prilocybine, cannabinoids, etc.

• Opiate narcotics/Opioids are the drugs derived from dried latex of unripe fruits of poppy plant (Papaver somniferum). They

are also called pain killers and have narcotic, analgesic, astringent (that causes contraction of body parts) and sedative effect, e.g., opium (afeem), heroin, smack, etc. • Cocaine is natural coca alkaloid obtained from leaves of coca (or cocca) plant (Erythroxylum coca). Cocaine has vasoconstrictor properties and acts as a good local anaesthetic. It is a powerful CNS stimulant. Its overdose causes hallucinations. • Hemp or cannabis compounds (hallucinogenic chemicals) are obtained from leaves, resin and flowering tips (inflorescence) of hemp plant that naturally have sedative effects, e.g., bhang, charas, ganja, marijuana, etc. • Tobacco has volatile poisonous alkaloid called nicotine which causes addiction. High concentration of nicotine paralyses nerve cells and may also lead to heart diseases. 74

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Addiction and Dependence • Addiction is a psychological attachment to certain effects such as euphoria and a temporary feeling of well-being that is

associated with drugs and alcohol. • Dependence is an adaptive state that develops from repeated drug administration. It can result in withdrawal syndrome

(anxiety, nausea, shivering), if the drug is abruptly discontinued. • Effects/symptoms of drug abuse include reckless behaviour, vandalism, violence, socially inactive, lack of concentration, etc.

Prevention and Control • Psychologists, psychiatrists, deaddiction and rehabilitation specialists are available to help individuals who fall in the trap of drug,

tobacco or alcohol abuse. • Teachers and parents should always be careful to look for and identify danger signs that can indicate tendency to go in for addiction. • Avoid undue pressure on child.

1. Read the following statements regarding dengue and choose the correct option given below. I. It is caused by Flavi-ribo virus. II. The virus is transmitted by Anopheles mosquito. III. Incubation period is 7-14 days. IV. This disease is also known as break bone fever. (a) I, III and IV (b) I and IV (c) II, III and IV (d) I and III 2. Read the following statements. A. Antibody consists of 6 peptide chains, four small and two long. B. Active immunity provides immediate relief. C. Primed cells remain dormant until activated once again by a new quantity of same antigen. D . Dendritic cells are non-phagocytic in nature. Of the above statements, (a) A and B are correct (b) A, B and D are correct (c) C and D are correct (d) B and C are correct. 3. A drug addict showing symptoms of drowsiness, lethargy, decreased weight and loss of interest in work. He is most probably addicted to (a) amphetamines (b) marijuana (c) cocaine (d) heroin. 4. Read the given statements and select the correct option. Statement A : A person, who has undergone an organ transplant, is given immunosuppressive drugs. Statement B : Immunosuppressive drugs suppress the immune system from rejecting the transplanted organ. (a) Both statements A and B are correct and statement B is the correct explanation of statement A. (b) Both statements A and B are correct but statement B is not the correct explanation of statement A.

10.

(c) Statement A is correct but statement B is incorrect. (d) Both statements A and B are incorrect. The cancers that are located in connective and muscular tissues derived from mesoderm are called (a) myomas (b) melanomas (c) sarcomas (d) lipomas. Nicotine is a component in tobacco products that stimulates the release of (a) dopamine (b) adrenaline (c) histamine (d) serotonin. Chagas disease is caused by A and it is transmitted by B . A B (a) Trypanosoma gambiense, Glossima palpalis (b) Trypanosoma gambiense, triatomids (c) Trypanosoma rhodesiense, Glossima morsitans (d) Trypanosoma cruzi, triatomids Identify the mismatched pair. (a) Tetanus toxoid - Active immunisation (b) Antivenom serum - Passive immunisation (c) Vaccine - Passive immunisation (d) Salk’s polio vaccine - Active immunisation Kala-azar disease is transmitted by (a) Dracunculus (b) Phlebotomus (c) Trypanoma (d) Balantidium. Study the given figure A showing interactions B b e t w e e n a n t i g e n s, C a n t i b o d i e s a n d c e l l involved in an allergic reaction. Identify A, B and C and choose the correct option. MT BIOLOGY

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A B C (a) IgM Granules of hapten Mast cell (b) IgG Granules of serotonin Basophil (c) IgE Granules of histamine Mast cell (d) IgA Granules of opsonin Histocytes 11. Match column I with column II and select the correct option from the codes given below. Column I Column II A. Microsporum canis (i) Measles B. Bordetella pertussis (ii) Syphilis C. Treponema pallidium (iii) Bubonic plague D. Rubeola virus (iv) Whooping cough E. Yersinia pestis (v) Ringworm (a) A-(iii), B-(i), C-(v), D-(ii), E-(iv) (b) A-(ii), B-(iv),C-(iii),D-(v), E-(i) (c) A-(iv), B-(iii), C-(i), D-(v), E-(ii) (d) A-(v), B-(iv), C-(ii),D-(i), E-(iii) 12. Read the following statements and select the correct option stating which ones include true (T) and which ones are false (F). I. Hepatitis B is transmitted by parenteral route. II. Symptoms of hepatitis include light coloured urine and dark stools. III. Hepatitis A virus has RNA as the genetic material. IV. Incubation period for Hepatitis A is 6-8 weeks. I II III IV (a) T T T F (b) F T T T (c) T F T F (d) F T F T 13. Study the chemical structure below and select the correct option regarding it. CH3 N

CH3 O H O H

(a) It is a crystalline powder obtained from plant Erythroxylon coca. (b) It has hallucinogenic properties obtained from hemp plant. (c) It is a psychedelic drug causing horrible dreams. (d) It is a type of opium derivative, strong analgesic with sedative and calming effects. 14. Rohan suffered from chicken pox when he was five years old. His body has developed life time resistance to the infection, due to (a) natural passive immunity 76

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(b) artificial active immunity (c) natural active immunity (d) artificial passive immunity. 15. Study the table and identify A, B, C and D. Disease

Site of infection

Effect

Taeniasis

Anaemia

Caecum and appendix

Bloody stools

Enterobiasis

Appendicitis

Giardiasis Small intestine D (a) A-Large intestine, B-Ancylostomiasis, C-Colon and appendix, D-Epigastric pain and fever (b) A-Small intestine, B-Trichuriasis, C-Caecum and colon, D-Epigastric pain and headache (c) A-Subcutaneous tissue, B-Ascariasis, C-Small intestine, D-Enlargement of spleen and fever (d) A-Caecum and appendix, B-Ascariasis, C-Large intestine, D-Enlargement of spleen and fever 16. Which of the following statements regarding antigenantibody complex is incorrect? (a) Neutralisation occurs when antibody-antigen reaction blocks bacterial toxins, viruses, etc., from affecting the body cells. (b) Clumping of blood cells or microorganisms due to antigen-antibody reaction is called agglutination. (c) Some antibodies can attack and rupture the plasma membrane of a cell causing precipitation. (d) Neighbouring cells aggregate when a single antibody binds with the epitopes of two or more different antigens at the same time. 17. Consider the following statements and select the correct option that fills the blanks. I. The lymphoid organ that is responsible for producing phagocytic macrophages is ______. II. _____ is pentamer in structure and cannot cross the placental barrier. III. _____ can induce antibody formation only when they combine with larger protein molecules serving as carriers. I II III (a) Peyerâ&#x20AC;&#x2122;s patches IgA Epitope (b) Thymus IgM Opsonins (c) Spleen IgM Haptens (d) Tonsils IgA Partial antigen 18. One difference between a cancer cell and a normal cell is that (a) the cancer cell is unable to synthesise DNA (b) the cell cycle of the cancer cell is arrested at the S-phase (c) cancer cells continue to divide in a regulated manner even when they are tightly packed

19.

20.

21.

22.

23.

24.

(d) cancer cells cannot function properly because they suffer from density-dependent inhibition. Live vaccine is a (a) low dose of the infectious bacteria administered as prophylactic (b) dose of modified bacterial strain devoid of its pathogenicity but retains immunogenicity (c) low dose of toxin that is produced by the bacterium (d) sample of cells from a patient who recently recovered from the disease. Match the terms given in column I with their description in column II and select the correct codes. Column I Column II A. Helper T-cells (i) Cells that are active in production of antibodies B. Plasma cells (ii) Enhance activity of cytotoxic T-cells C. Killer T-cells (iii) Inhibit function of cytotoxic T-cells D. Suppressor T-cells (iv) Secrete perforins (a) A-(iv), B-(i), C-(ii), D-(iii) (b) A-(iii), B-(ii), C-(i), D-(iv) (c) A-(i), B-(iii), C-(iv), D-(ii) (d) A-(ii), B-(i), C-(iv), D-(iii) Malignant malaria is caused by (a) Plasmodium malariae (b) Plasmodium ovale (c) Plasmodium falciparum (d) Plasmodium vivax. Which of the following is not a symptom of typhoid? (a) Low pulse rate with high fever (b) Abdominal pain with high pulse rate (c) Low pulse rate and frequent stools (d) Both (a) and (b) An autoimmune disease in which the body destroys the functioning of thyroid gland is (a) Simmond’s disease (b) Grave’s disease (c) Hashimoto’s disease (d) Addison’s disease. Match column I which lists the components of body defense with column II that lists the corresponding description and choose the correct option. Column I Column II A. Active natural p. Injection of gamma immunity globulins B. First line of q. Complement proteins and defense interferons C. Passive natural r. Direct contact with the immunity pathogens that have entered inside body D. Second line of s. Lysozyme and skin defense t. Antibodies transferred through the placenta

(a) A-s, B-r, C-t, D-p (c) A-r, B-s, C-t, D-q

(b) A-r, B-s, C-p, D-t (d) A-t, B-r, C-q, D-p

25. The transplantation between the individuals of same species of different genetic background is (a) autograft (b) allograft (c) isograft (d) xenograft. 26. HIV decreases natural immunity of body by (a) attacking T-lymphocytes (b) attacking B-lymphocytes (c) destroying antibodies (d) destroying erythrocytes. 27. Which of the following is correct option for bacterial diseases? I. Hansen’s disease II. Measles III. Yellow fever IV. Lock jaw V. Whooping cough VI. Flu (a) II, III, V and VI (b) I, III and VI (c) I, IV and V (d) IV, V and VI 28. Elephantiasis is caused by (a) aschelminthes (b) platyhelminthes (c) viruses (d) protozoans. 29. Match column I with column II and select the correct option. Column I Column II 1. LSD (i) Erythroxylon 2. Caffeine (ii) Thea sinensis 3. Cocaine (iii) Cannabis 4. Hashish (iv) Ergot alkaloid (a) 1-(iv), 2-(iii), 3-(i), 4-(ii) (b) 1-(i), 2-(ii), 3-(iii), 4-(iv) (c) 1-(iv), 2-(iii), 3-(ii), 4-(i) (d) 1-(iv), 2-(ii), 3-(i), 4-(iii) 30. Which of the following statements is incorrect? (a) An alcoholic may suffer from cholestasis. (b) Mallory-Weiss syndrome is characterised by oesophagitis and gastritis. (c) Alcohol consumption can effect the haemopoietic system by decreasing the RBC size. (d) Cerebrum is the first part of brain affected after alcohol consumption.

ANSWER KEY 1. (b) 6. (b) 11. (d) 16. (c) 21. (c) 26. (a)

2. 7. 12. 17. 22. 27.

3. 8. 13. 18. 23. 28.

(d) (c) (d) (c) (c) (a)

4. 9. 14. 19. 24. 29.

(a) (b) (c) (b) (c) (d)

5. 10. 15. 20. 25. 30.

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Time Allowed : 3 hours

Maximum Marks : 70 GENERAL INSTRUCTIONS

(i) There are total 26 questions in five sections in the question paper. All question are compulsory. (ii) Section A contains questions number 1 to 5. Very Short Answer type questions of one mark each. (iii) Section B contains questions number 6 to 10. Short Answer type-I questions of two marks each. (iv) Section C contains questions number 11 to 22. Short Answer type-II questions of three marks each. (v) Section D contains question number 23. Value Based Question of four marks. (vi) Section E contains questions number 24 to 26. Long Answer type questions of five marks each. (vii) There is no overall choice in the question paper, however, an internal choice is provided in one question of two marks, one question of three marks and all three questions of five marks. An examinee is to attempt any one question out of the two given in the question paper with the same question number.

SECTION - A 1. Our government has intentionally imposed strict conditions for MTP in our country. Justify giving a reason. 2. State the fate of a pair of autosomes during gamete formation. 3. What role does an individual organism play as per Darwin's theory of natural selection? 4. Suggest a method to ensure an anamnestic response in humans. 5. What is biopiracy? SECTION - B 6. A mature embryo sac in flowering plant may possess 7-cells, but 8-nuclei. Explain with the help of diagram only. 7. Describe the structure of a nucleosome. OR Mention the evolutionary significance of the following organisms. (a) Shrews (b) Lobefins (c) Homo habilis (d) Homo erectus 8. In an agricultural field there is a prevalence of the following organisms and crop diseases which are affecting the crop yield badly (a) White rust (b) Leaf and stripe rust (c) Black rot (d) Jassids 78

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Recommend the varieties of crops the farmers should grow to get rid of the existing problem and thus improve the crop yield. 9. How does the application of the fungal genus, Glomus, to the agricultural farm increase the farm output? 10. Plenty of algal bloom is observed in a pond in your locality. (a) Write what has caused this bloom and how does it affect the quality of water. (b) Suggest a preventive measure. SECTION - C 11. (a) List the three stages the annuals and biennial angiosperms have to pass through during their life cycle. (b) List and describe any two vegetative propagules in flowering plants. 12. Draw a labelled diagrammatic sectional view of a human seminiferous tubule. 13. During a medical investigation, an infant was found to possess an extra chromosome 21. Describe the symptoms the child is likely to develop later in the life. 14. A number of passengers were severely burnt beyond recognition during a train accident. Name and describe a modern technique that can help in handing over the dead to their relatives.

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15. p2 + 2pq + q2 = 1. Explain the algebraic equation on the basis of Hardy Weinberg's principle.

16. (a) What precaution(s) would you recommend to a patient requiring repeated blood transfusion?

(b) If the advise is not followed by the patient, there is an apprehension that the patient might contract a disease that would destroy the immune system of his/her body. Explain with the help of schematic diagram only how the immune system would get affected and destroyed. 17. (a) What is inbreeding depression? (b) Explain the importance of "selection" during inbreeding in cattle. 18. Describe how do 'flocs' and 'activated sludge' help in sewage treatment. 19. Explain the role(s) of the following in Biotechnology : (a) Restriction endonuclease (b) Gel-electrophoresis (c) Selectable markers in pBR322. 20. Write the steps you would suggest to be undertaken to obtain a foreign-gene-product. 21. Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen. 22. (a) 'in-situ' conservation can help endangered/threatened species. Justify the statement.

(a) Arrange the following hormones in sequence of their secretion in a pregnant woman. (b) Mention their source and the function they perform. hCG; LH; FSH; Relaxin 25. State and explain the "law of independent assortment" in a typical Mendelian dihybrid cross. OR (a) How do the observations made during moth collection in pre- and post-industrialised era in England support evolution by Natural Selection? (b) Explain the phenomenon that is well represented by Darwin's finches other than natural selection. 26. (a) What is an age-pyramid? (b) Name three representative kinds of age-pyramids for human population and list the characteristics for each one of them. OR Discuss the role of healthy ecosystem services as a pre-requisite for a wide range of economic, environmental and aesthetic goods and services.

SOLUTIONS

(b) Name and describe any three causes of biodiversity losses.

1. Government of India imposed strict conditions for MTP because it is being misused for sex determination and illegal abortions of female fetuses. It may lead to the death of many women.

SECTION - D 23. Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident's Welfare Association of your locality organised an awareness programme entitled "Bury not burn". They invited you, being a biology student to participate. (a) How would you justify your arguments that promote burying and discourage burning? (Give two reasons) (b) With the help of flow charts, one for each practice depict the chain of events that follow. SECTION - E 24. Read the following statement and answer the questions that follow : "A guava fruit has 200 viable seeds." (a) What are viable seeds? (b) Write the total number of : (i) Pollen grains (ii) Gametes in producing 200 viable guava seeds. 80

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2. A pair of autosomes get segregated by means of meiotic division and produce haploid gametes during gametogenesis. 3. According to the Darwin's theory of natural selection, an individual organism would lead to evolution of new species as it adds variations by random mating and nature selects the fittest organism, resulting in inheritance of useful variations and evolution of new species. 4. To ensure anamnestic or secondary immune response, dead or attenuated pathogens of a disease can be injected into a healthy person that can produce memory cells i.e., vaccination. 5. Biopiracy is the commercial exploitation or patenting of biological resources of a nation by some other organisation or company without proper authorisation from concerned country. 6. A mature embryo sac in a flowering plant possesses 7 cells but have 8 nuclei.

3 cells

Embryo sac

7. DNA packing of eukaryotes is carried out with help of lysine and arginine rich basic proteins called histones. The unit of compaction is nucleosome. There are five types of histone proteins - H1, H2A, H2B, H3 and H4. Four of them (H2A, H2B, H3 and H4) occur in pairs to produce histone octamer, called nu body or core of nucleosome. Their positively charged ends are towards the outside. They attract negatively charged 3 strands of DNA. DNA over nu body forms 1 turns to form 4 nucleosome core. A typical nucleosome contains 200 bp of DNA helix. DNA connecting two adjacent nucleosomes is called interbead or linker DNA. It bears H1 histone protein. Nucleosome chain gives a bead on string appearance. OR (a) Shrews-The first mammals evolved in the earth were like shrews, who existed 2,00,000 years ago. Their fossils show that they were small sized. They were viviparous, more intelligent and avoided dangers because of better senses. (b) Lobefins-Lobefins are fishes which were considered to be extinct 65 million years ago, until one was captured in 1938 in South Africa. They are considered living fossils as they were the first amphibians that lived both on land and water. They were ancestors of modern day frog and salamander. (c) Homo habilis - Homo habilis (able or skillful man, the tool maker or handyman) was the transition man, who evolved from Australopithecus. He lived in Africa about 2 million years ago. The teeth and bipedal locomotion were like that of modern man. Homo erectus evolved from them. (d) Homo erectus - Homo erectus appeared about 1.7 million years ago in middle pleistocene in central Java (1891). H. erectus evolved from Homo habilis. His skull was flatter than that of modern man. Also some primitive type of speech had developed and use of fire may be known. 8. Following resistant varieties of crop should be grown by the farmers to get rid of the problem of crop diseases and yield.

(a) White rust – Pusa Swarnim variety of Brassica (b) Leaf and stripe – Himgiri variety of wheat rust (c) Black rot – Pusa Shubhra, Pusa Snowball K-1 varieties of Cauliflower (d) Jassids – Pusa Sem-3 or Pusa Sem-2 varieties of flat beans 9. Many members of the genus Glomus form symbiotic associations with plants to form mycorrhiza. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also, such as resistance to root-borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development. Therefore, Glomus increases the farm yield. 10. (a) Algal bloom is the excess growth of planktonic algae that causes colouration of water. It is caused due to passage of sewage and run off from fertilised fields into ponds, lakes and other water bodies. Nutrients present in sewage and fertilisers cause nutrient enrichment or eutrophication particularly with nitrogen and phosphorus. Algal blooms cut off light and oxygen for submerged plants and aquatic life causing their death. They cause deterioration of the water quality and fish mortality. (b) Farmers should find the alternates for fertilisers like manures and compost. Domestic or industrial wastes with organic nutrients must be treated before passing into water bodies. 11. (a) The three stages that angiosperms have to pass through are: (i) Vegetative phase (ii) Reproductive phase (iii) Senescence phase (b) (i)

Roots : Modified tuberous roots of sweet-potato, tapioca, yam, Dahlia and Asparagus can be propagated vegetatively when planted in soil. The buds present on the roots grow into leafy shoots above ground and adventitious roots at their bases. Adventitious buds develop on the ordinary roots of Dalbergia sisso, Populus, Guava, etc., and grow to form new plants. (ii) Rhizomes : Rhizomes are underground modified stem that serve as means of vegetative propagation by perennating under unfavourable conditions. They produce new aerial shoots during the favourable season. Typha, Canna, ginger, turmeric, lotus, Saccharum, water hyacinth and many other plants propagate vegetatively with the help of rhizomes.

For more solutions refer to Mtg CBSE Chapterwise topicwise. MT BIOLOGY

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-1

Class XII

• Reproduction in Organisms • Sexual Reproduction in Flowering Plants Total Marks : 160

Duration : 40 Min.

1. The type of vegetative propagation used by horticulturists to multiply trees like litchi and pomegranate is (a) air layering (b) trench layering (c) serpentine layering (d) mound layering. 2. Match the following and select the correct option. Column I Column II A. Homogametes (i) Cladophora B. Dioecious (ii) Fucus C. Heterogametes (iii) Papaya D. Monoecious (iv) Chlamydomonas E. Zygotic meiosis (v) Maize (a) A-(i); B-(iii); C-(ii); D-(v); E-(iv) (b) A-(ii); B-(iv); C-(i); D-(v); E-(iii) (c) A-(iii); B-(i); C-(ii); D-(iv); E-(v) (d) A-(v); B-(i); C-(iv); D-(iii); E-(ii)

5. Which of the following is not a function of tapetum? (a) It secretes enzymes like callase for degradation of callose wall around pollen tetrad. (b) It produces Ubisch granules containing sporopollenin for exine formation. (c) It secretes pectinase enzyme for dehiscence in the ripe anther. (d) It provides nourishment for pollen grains and microspore mother cells.

3. Study the given figure of an embryo sac and select the correct option for the labelled parts A-E. A B C D E A

(a)

Synergids

Oosphere

Polar nuclei

Central cell

Antipodal cells

(b)

Oosphere

Polar nuclei

Antipodal cells

Central cell

Synergids

(c)

Polar nuclei

Oosphere

Synergids

Nucellus

Central cell

(d)

Antipodal cells

Oosphere

Polar nuclei

Central cell

Synergids

MT BIOLOGY

TODAY | MAY ‘17

4. Select the correctly matched pair. (a) Rhizomes - Colocasia (b) Bulbs - Garlic (c) Corms - Artichoke (d) Tubers - Adiantum

6. Read the given statements. (i) The division of multinucleate parent into many multinucleate daughter individuals without nuclear division is called plasmotomy. (ii) Exogenous budding is observed in Spongilla. (iii) Broken tail of lizard is replaced by epimorphosis. (iv) Ephyra larvae of Aurelia are formed by fragmentation. Of the above statements, the incorrect ones are (a) (i), (ii) and (iv) (b) (i) and (iii) (c) (ii) and (iv) (d) (iii) and (iv). 7. Self pollination helps in (a) ensuring seed production without producing large number of pollen grains (b) introducing variations and genetic recombination in the progeny (c) increasing hybrid vigour (d) making plants resistant to diseases. 8. In Cucurbita, the pollen tube enters the ovule through the _______ and is known as ______.

(a) micropyle, mesogamy (b) integuments, mesogamy (c) funicle, mesogamy (d) chalaza, chalazogamy

9. In ovoviviparous animals (a) the egg remains inside the mother’s body after fertilisation and placenta develops for nourishment (b) the mother gives birth to the young one (c) the mother lays unfertilised calcareous eggs (d) the development of the embryo takes place outside the mother’s body. 10. Identify the technique of grafting from the given statements. I. Numerous scions are selected and cut at the base to form wedges. II. Many slits are formed on stock. III. Stock has larger diameter than scions. IV. Scions are inserted in the slits and held by bandages. (a) Approach grafting (b) Crown grafting (c) Side grafting (d) Wedge grafting 11. The type of ovule that is half inverted and at right angle to the funiculus is called (a) anatropous ovule (b) hemitropous ovule (c) circinotropous ovule (d) amphitropous ovule. 12. Read the following statements and select the correct option. Statement 1 : There is no genetic variability in vegetatively propagated plants. Statement 2 : The plants obtained vegetatively degenerate easily as they show less adaptability to the changes in environment. (a) Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1. (b) Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1. (c) Statement 1 is true but statement 2 is false. (d) Both statements 1 and 2 are false. 13. Match column I with column II and column III and select the correct option. Column I Column II Column III A. Offset (i) One internode p. Vallisneria long runners B. Runners (ii) Slender underground q. Oxalis branches at base of aerial stem C. Suckers (iii) Narrow, green, r. Pistia horizontal branches at the base of a crown D. Stolons (iv) Arched horizontal s. Mint branches at the base of a crown (a) A-(i)-r; B-(iii)-q; C-(ii)-s; D-(iv)-p (b) A-(ii)-q; B-(i)-r; C-(iv)-p; D-(iii)-s

14. Select the wrongly matched pair. (a) Exine - Sporopollenin (b) Intine - Pecto-cellulosic (c) Pollen mother cells - Callose (d) Pollenkitt - Proteins 15. Read the following statements about a dicot embryo and select the option that correctly fills the blanks. (i) The part of embryonal axis that is present above the level of cotyledons is called ______. (ii) ______ is the part of embryonal axis present below the level of cotyledons. (iii) The root tip is called ______. (i) (ii) (iii) (a) hypocotyl Epiblast calyptra (b) epicotyl Hypocotyl radicle (c) plumule Coleoptile epiblast (d) epiblast Epiblast calyptra 16. The spores that are produced exogenously, either singly or in chains, by constriction at the tip of special hyphal branches are called (a) oidia (b) sporangiospores (c) conidia (d) chlamydospores. 17. Identify the type of pollination from the given floral characteristics. I. Pollen grains are light, smooth, non-sticky and dry. II. Anthers and stigma are protruding. III. Flowers are small, colourless and nectarless. IV. Stigma is hairy and feathery. (a) Hydrophily (b) Anemophily (c) Zoophily (d) Entomophily

Make as many biological terms as possible using the given letters. Each word should contain the letter given in circle. 2. Minimum 4 letter word should be made. 3. In making a word, a letter can be used as many times as it appears in the box. 4. Make at least 1 seven letter word.

A N U

M O Y

M E C

H S

L A N

Send your response at editor@mtg.in or post to us with complete address by 25th of every month to win exciting prizes. Winners’ name will be declared on 1st of every month on www.mtg.in

MT BIOLOGY

TODAY | MAY ‘17

18. Which of the following is false regarding fertilisation? (a) In algae and fishes, fusion of gametes occurs outside the body. (b) In internal fertilisation, mobile male gamete travels to female gamete to fuse with it. (c) Internal fertilisation occurs in gymnosperms, amphibians, birds, mammals, etc. (d) Offsprings are not protected from the predators in external fertilisation. 19. Consider the given statements and select the correct option stating which statements are true (T) and which are false (F). (i) Strobilation is observed in the neck of Taenia. (ii) Estrous cycle is present in mammals like dog, cats, monkeys, etc. (iii) Parthenium is the major contributor to pollen allergy. (iv) Viability of seeds can be tested by immersing the seed in 0.1% solution of triphenyl formazan. (i) (ii) (iii) (iv) (a) T F T F (b) F F T F (c) T T F T (d) F F T T 20. Pollination which involves transfer of pollen from anther of one flower to stigma of genetically different flower is called (a) geitonogamy (b) cleistogamy (c) anisogamy (d) xenogamy. 21. When pollen grains from another flower germinate faster than the pollen grains of the same flower over the stigma, it is called (a) dichogamy (b) herkogamy (c) dicliny (d) prepotency. 22. Given figures represents sporulation in various organisms. C B A

Select the option which correctly identifies A, B and C. (a) (b) (c) (d) 84

A Conidia Chlamydospores Sporangiospores Conidia MT BIOLOGY

B Chlamydospores Oidia Chlamydospores Oidia

TODAY | MAY â&#x20AC;&#x2DC;17

C Sporangium Sporangiospores Oidia Chlamydospores

23. Identify the type of parthenogenesis in which only females are produced. (a) Arrhenotoky in mites (b) Thelytoky in lizards (c) Amphitoky in aphids (d) Arrhenotoky in honey bees 24. Study the given statements and select the incorrect one. (i) Testa is outer, one layered, thick covering of seed. (ii) Coleorhiza protects the plumule during its emergence from soil. (iii) Pericarp is unused nucellus in the seed. (iv) Coleorhiza does not come out of soil and remains nongreen. (a) (i), (ii) and (iii) only (b) (ii) and (iv) only (c) (i), (iii) and (iv) only (d) (ii) and (iii) only 25. Double fertilisation was discovered by (a) Strasburger (b) Dickson (c) Charles Bonnet (d) Nawaschin. 26. Identify the mismatched pair. (a) Obligatory parthenogenesis - Typhlina brahmina (b) Cyclic parthenogenesis - Turkeys (c) Artificial parthenogenesis - Star fish (d) Paedogenetic parthenogenesis - Wasps 27. Which of the following statements is incorrect? (a) In Bryophyllum, uninjured fallen leaves develops into new plants from marginal buds. (b) Turion in Utricularia remains dormant under unfavourable conditions and in the favourable conditions forms a new plant. (c) In Agave, floral buds show vegetative propagation through bulbils. (d) Stolons are arched horizontal branches that cause vegetative propagation in Eichhornia. 28. Adventive embryony occurs when (a) an embryo is haploid and formed without meiosis and syngamy (b) all embryo-sac cells including egg are diploid and can form normal embryos (c) an embryo is formed directly from diploid egg without fertilisation (d) an embryo is formed directly from a diploid cell other than egg, like integument or nucellus. 29. Which of the following statements is correct about chasmogamous flowers? (a) The flowers are open, exposing anthers and stigmas. (b) Flowers do not undergo self pollination. (c) The flowers remain closed and are self pollinated. (d) The anthers dehisce inside the closed flower. 30. Root cuttings are used to artificially propagate (a) Bougainvillea (b) Saintpaulia (c) blackberry (d) grapes.

31. Identify the correct statement. (a) Morphallaxis is the regeneration of a lost body part. (b) Gemmules in fresh water sponges forms new colony. (c) In a pollen grain, exine is pecto-cellulosic in nature. (d) Polygonum type of embryo-sac contains 9 nuclei and 8 cells. 32. Fusion of two organisms that themselves act as gametes is called (a) endogamy (b) conjugation (c) oogamy (d) hologamy. 33. Match column I with column II and select the correct option. Column I Column II A. Bud grafting (p) Pineapple B. Stimulative parthenocarpy (q) Pear C. Trench layering (r) Apple D. Vegetative parthenocarpy (s) Grapes E. Bulbils (t) Walnut (a) A-r, B-s, C-t, D-q, E-p (b) A-s, B-p, C-r, D-q, E-t (c) A-q, B-p, C-s, D-t, E-r (d) A-t, B-q, C-p, D-s, E-r 34. The seeds may become non-viable due to (i) denaturation of enzymes (ii) premature RNA exhaustion (iii) damage to embryo (iv) excessive dry weather. (a) (i) and (iii) only (b) (i), (ii) and (iv) only (c) (ii) and (iii) only (d) All of these 35. Which of the following is not an event that occurs during double fertilisation? (a) A diploid zygote is formed from the fusion of male and female gamete. (b) A triploid endosperm is formed after vegetative fertilisation. (c) Formation of nutritive tissue starts before the embryo formation. (d) Growth of female gametophyte stops at 7-celled or 8-nucleate stage. 36. Ornithophilous flowers are usually (a) bright, secrete abundant nectar and scent is absent (b) dull coloured, have strong fruity odour and secrete abundant nectar

37. Which of the following pairs are monocarpic plants? (a) Strobilanthus, Grape vine (b) Rice, China rose (c) Bambusa, Orange (d) Carrot, Wheat 38. Read the given statements and select the correct option. Statement 1 : In Salvia, a lever-mechanism promotes cross pollination. Statement 2 : Salvia has protandrous and anemophilous flowers. (a) Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1. (b) Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1. (c) Statement 1 is true but statement 2 is false. (d) Both statements 1 and 2 are false. 39. Refer to the given table about transformation of flower parts and select the option that correctly fills the blanks in it. Pre-fertilisation

Post-fertilisation

Micropyle of ovule

Pericarp

Outer integument

Nucellus

A (a) Perisperm (b) Micropyle of seed (c) Micropyle of seed (d) Thalamus

B Ovary wall Ovule

C Perisperm Perisperm

D Tegmen Disappear

Ovary wall

Testa

Perisperm

Ovule

Testa

Disappear

40. If the numbers of chromosomes in the aleurone layer of a seed is 60, what must have been the number of chromosomes present in megaspore mother cell? (a) 30 (b) 20 (c) 10 (d) 40 Key is published in this issue. Search now! J

Check your score! If your score is > 90%

ExcELLEnT wOrk !

You are well prepared to take the challenge of final exam.

No. of questions attempted

……

90-75%

GOOD wOrk !

You can score good in the final exam.

No. of questions correct

……

74-60%

sATIsfAcTOrY !

You need to score more next time.

Marks scored in percentage

……

< 60%

nOT sATIsfAcTOrY! Revise thoroughly and strengthen your concepts.

MT BIOLOGY

TODAY | MAY ‘17

MT BIOLOGY

TODAY | MAY â&#x20AC;&#x2DC;17