Biology Past Paper PDF - National Standard Examination in Biology 2019-20

## Indian Association of Physics Teachers National Standard Examination in Biology 2019-20 **Question Paper Code: 21** **Date of Examination: November 24, 2019** **Time: 2:00 PM to 4:00 PM** ### Instructions to Candidates: 1. Use of mobile phones, smart watches, and iPads during examination is st...

## Indian Association of Physics Teachers National Standard Examination in Biology 2019-20 **Question Paper Code: 21** **Date of Examination: November 24, 2019** **Time: 2:00 PM to 4:00 PM** ### Instructions to Candidates: 1. Use of mobile phones, smart watches, and iPads during examination is strictly prohibited. 2. In addition to this question paper, you are given OMR Answer Sheet along with Candidate's copy. 3. On the Answer Sheet, make all the entries carefully in the space provided only in block capitals as well as by properly darkening the appropriate bubbles. Incomplete, incorrect, or carelessly filled information may disqualify your candidature. 4. On the OMR Answer Sheet, use only blue or black ball point pen for making entries and filling the bubbles. 5. Your ten-digit roll number and date of birth entered on the OMR Answer Sheet shall remain your login credentials - login ID and password respectively for accessing your performance/result in NSE-2019. 6. Question paper has 80 multiple-choice questions. Each question has four alternatives, out of which only one is correct. Choose the correct alternative and fill the appropriate bubble, as shown. 7. A correct answer carries 3 marks whereas 1 mark will be deducted for each wrong answer. 8. Any rough work should be done only in the space provided on the question paper. 9. Use of non-programmable scientific calculator is allowed. 10. No candidate should leave the examination hall before the completion of the examination. 11. After submitting your Answer Sheet, take away the Candidate's copy for your reference. **Please DO NOT make any mark other than filling the appropriate bubbles properly in the space provided on the answer sheet.** **Answer sheets are evaluated using machine, hence CHANGE OF ENTRY IS NOT ALLOWED. Scratching or overwriting may result in a wrong score.** **DO NOT WRITE ON THE BACK SIDE OF THE ANSWER SHEET.** ### Instructions to Candidates (Continued): You may read the following instructions after submitting the Answer Sheet. 12. Comments/Inquiries/Grievances regarding this question paper, if any, can be shared on the Inquiry/Grievance column on www.iaptexam.in on the specified format till November 27, 2019. 13. The answers/solutions to this question paper will be available on the website www.iapt.org.in by December 2, 2019. 14. **CERTIFICATES and AWARDS** Following certificates are awarded by IAPT/ATBS to the students successful in the **NATIONAL STANDARD EXAMINATION IN BIOLOGY - 2019**: - "CENTRE TOP 10%" - "STATE TOP 1%" - "NATIONAL TOP 1%" - "GOLD MEDAL & MERIT CERTIFICATE" to all students who attend OCSC - 2020 at HBCSE Mumbai 15. All these certificates (Except Gold Medal) will be sent/dispatched to the centre in-charge by February 1, 2020 along with the result sheet of the centre. 16. List of students (with centre number and roll number only) having score above MAS will be displayed on the web www.iapt.org.in by December 20, 2019. See the Minimum Admissible score Clause on the Student's brochure on the web. 17. List of Students eligible for National Biology Olympiad (INBO - 2020) shall be displayed on www.iapt.org.in by December 28, 2019. These students have to register/enroll themselves on the website: Olympiads.hbcse.tifr.in of HBCSE Mumbai within the specified period. ### National Standard Examination In Biology (NSEB 2019-20) **Time: 120 Minute** **Max. Marks: 240** **Attempt All the Eighty Questions** **ONLY ONE OUT OF FOUR OPTIONS IS CORRECT** 1. The function of contractile vacuole is to pump out excess water from the cell. In _Paramecium_, the activity of contractile vacuole was found to increase when transferred from one medium to another. Hence it can be concluded that the transfer was from: a) isotonic to hypotonic solution. b) hypotonic to isotonic solution. c) hypotonic to hypertonic solution. d) isotonic to hypertonic solution. 2. Enzyme A has a higher Km value than enzyme B, although both can achieve the same Vmax. Hence it can be concluded that: a) enzyme A requires higher substrate concentration and has lower affinity to substrate than enzyme B. b) enzyme A requires lower substrate concentration and has lower affinity to substrate than enzyme B. c) enzyme A requires higher substrate concentration and has higher affinity to substrate than enzyme B. d) enzyme A requires lower substrate concentration and has higher affinity to substrate than enzyme B. 3. Average molecular weight of amino acid is considered to be 110 Da. A homodimeric membrane protein is found to have a molecular weight of 44,000 Da. How many amino acids are present in each monomer of the protein? a) 400 b) 300 c) 200 d) 100 4. The graphs show the data on sex determination of the progeny which is dependent on temperature. * **MT = Male favouring Temperature; FT = Female favouring Temperature; Tp = Temperature obtaining ratios at equilibrium** **Case I** * A graph showing percentage female on the y axis and temperature on the x axis. The curve starts at 100%, decreases sharply to around 50% at the middle then increases again to 100% at the end. **Case II** * A graph showing percentage female on the y axis and temperature on the x axis. The curve starts at 0%, increases steadily to 100% at the middle, and then decreases steadily again to 0%. **Case III** * A graph showing percentage female on the y axis and temperature on the x axis. The curve starts at 100%, decreases slowly and gradually levels out at 50%, before increasing again to 100%. A few statements regarding the data are made: - i. Case I: At a mid-range temperature, 3:1 is a predicted the male: female ratio. - ii. Case II: The number of males will be much higher at lower temperatures. - iii. Case III: The number of females: males will always be higher at temperature extremes. - iv. Case I and II are likely to face ratio imbalance at mid ranges of temperatures. The correct statement/s is/are: a) ii only b) i and ii c) ii and iii d) iii and iv 5. The given table showing the recombination frequencies between different gene loci on the same chromosome. Recombination frequencies are directly related to the distance between the two genes. Higher the recombination frequency, greater the distance between the two loci. However, even if the actual distance exceeds 50 units, the recombination frequency does not exceed 50%. Select the most probable arrangement of genes based on the data below: | Gene pairs | Recombination frequency | |---|---| | Ab | 50 | | ac | 7 | | Ad | 22 | | bc | 50 | | bd | 50 | | Cd | 15 | a) d-c-a-b/b-a-c-d b) b-d-a-c / c-a-d-b c) c-d-a-b/b-a-d-c d) d-a-c-b/b-c-a-d 6. The compartmentalization of the cytoplasm by the membranes of the endoplasmic reticulum (ER) results in: a) increasing the surface area available for biochemical synthesis. b) providing a structural framework. c) facilitating cell mobility. d) maintaining cell fluidity and cell dynamics. 7. Cross pollination will take place when: - i. the flowers are Cleistogamous (flowers never open). - ii. the flowers show Herkogamy (physical barrier between anther and style). - iii. the flowers show Dichogamy (stamens and carpels of bisexual flowers mature at different times). - iv. the plants are Dioecious (plants having unisexual flower). Choose the correct option: a) ii only b) i and iii c) ii and iii d) ii, iii and iv 8. Predict the phenotype of a promoter mutant (lacP) for the lac operon. a) The lac genes would be expressed efficiently only in the absence of lactose. b) The lac genes would be expressed efficiently only in the presence of lactose. c) The lac genes would be expressed continuously. d) The lac genes would never be expressed efficiently. 9. A tall plant with red flowers is crossed with a dwarf plant that produces white flowers. In F1 all plants are tall with pink flowers. The F1 plant is crossed with dwarf parent that bears white flower. Four types of progenies were produced in a ratio of 102: 98: 103: 99. The progenies expressed: a) All the five characters of parents and F1. b) All the characters except pink colour of the flower. c) All characters except white colour of the flower. d) All characters except red. 10. Thyroid gland produces hormones which control the rate of metabolism in animals. Which of the following would occur if the thyroid of cattle is fed to a man deficient in thyroid secretion? - i) It will speed up his metabolism. - ii) It will lower the rate of his metabolism. - iii) It will regulate the hormone secretion. - iv) It will not have any effect on hormone secretion. Which of the following are correct options? a) i and iv b) ii and iii c) i and iii d) ii and iv 11. Removal of which of the components from the given food chain will not result in complete collapse of the food chain? **Producers → Primary consumers → Secondary consumers → Decomposers** a) Producers and primary consumers. b) Primary consumers and secondary consumers. c) Secondary consumers and decomposers. d) Producers and decomposers. 12. Patterns of diffusion for two molecules A and B for a living cell are shown in the graph. * A graph showing rate of solute movement (v) on the y axis and solute concentration on the x axis. There are 2 curves - A and B. Curve A starts at 0 and increases rapidly, levels off at a plateau then increases again rapidly and levels off. Curve B also starts at 0 and increases steadily, levels off at a plateau and then increases slowly. * **A - Protein-mediated transport (facilitated diffusion)** * **B - Simple diffusion** A and B most likely could be, respectively: a) Na+ and Glucose b) O2 and CO2 c) Glucose and O2 d) O2 and glycerol. 13. Suppose a leaf containing chlorophyll 'a' molecule is irradiated at its absorption maxima i.e. 450 nm and 662 nm. The fluorescence emission of this leaf would be at 668 and 723 nm. If now the leaf is irradiated with either 400 nm or 550 nm wavelength of light then, the fluorescence emission of this leaf would probably be at: a) 668 and 723 nm b) 610 and 700 c) 610 nm only d) 610 and 668 nm 14. During transmission of impulses across the nerve membrane, a simple impulse dies out just before the synapse, whereas several impulses reaching the synapse within a short period "Fire" the impulse into the next neuron. The reason for simple neuron to die out maybe that the: a) synapse gets fatigued by continuous work. b) impulse is unable to produce the adequate quantity of neurotransmitters. c) speed at which impulse travels is less. d) dendrites of nerve fibres take time to accept signal for nerve impulse. 15. Double fertilization is not found in: a) Cucumber b) Rice c) Pinus d) Mango 16. Which of the following diploids produce ß-galactosidase, in the absence of lactose? a) placZ-lac/+p + lacZ + lacI- b) placZ-lacI-/p-lacZ+lacI- c) p + lacZ+ lacI-/p+lacZ + lacI- d) p + o lacZ-lacI+ / p o+lacZ + lacI + 17. How many meiotic divisions will be required for the formation of 80 zygotes in an angiospermic plant? a) 40 b) 100 c) 80 d) 160 18. A food chain in a terrestrial ecosystem is shown. **Sun → Grass → Rabbit → Snake** The food chain is incomplete due to: a) Absence of tertiary consumer. b) Absence of decomposers. c) Absence of quaternary consumer. d) Absence of parasitic component. 19. Eutrophication is considered bad for a water body because it leads to: a) increase in demand for carbon dioxide. b) increase in demand for oxygen. c) increase in demand for nitrogen. d) change in pH of the water body. 20. Cells of _E. coli_ are placed in a solution with 12% NaCl. Which effect would be visible after 24h of incubation? a) Plasmolysis. b) Plasmoptysis. c) Osmotic lysis. d) Swelling of cells. 21. Mutations in the genome of _E. coli_ are introduced at a rate of 1/10^9 bp per generation. If a scientist starts with a colony of 10^6 cells having 1000 bp DNA, the number of mutant cells observed after two doubling times will be: a) At least 2. b) Not more than 4. c) At least 4. d) 0. 22. _E. coli_ can utilize glucose as well as lactose as carbon source for growth and multiplication. Which of the following graphs (a – d ) correctly reflect the levels of ß-galactosidase, if these organisms is grown in a media containing glucose as well as lactose? * **Graph (a)** * A graph showing relative cell density on the y axis and time on the x axis. There are 2 curves - relative cell density and relative level of beta galactosidase. Both curves start at 0 and rise steadily and plateaus at a steady level. Relative level of beta galactosidase always stays below relative cell density. * **Graph (b)** * A graph showing relative cell density on the y axis and time on the x axis. There are 2 curves - relative cell density and relative level of beta galactosidase. Both curves start at 0 and rise steadily and plateaus at a steady level. Relative level of beta galactosidase initially follows relative cell density, then drops and remains lower than relative cell density till the end of the graph. * **Graph (c)** * A graph showing relative cell density on the y axis and time on the x axis. There are 2 curves - relative cell density and relative level of beta galactosidase. Both curves start at 0 and rise steadily and plateaus at a steady level. Relative level of beta galactosidase always follows relative cell density closely. * **Graph (d)** * A graph showing relative cell density on the y axis and time on the x axis. There are 2 curves - relative cell density and relative level of beta galactosidase. Both curves start at 0 and rise steadily and plateaus at a steady level. Relative level of beta galactosidase follows relative cell density closely, then drops and remains lower than relative cell density till the end of the graph. 23. If a budding yeast cell is compared to a mitotically dividing cell, the most likely difference observed will be in: a) conventional prophase. b) conventional metaphase. c) conventional anaphase. d) conventional telophase. 24. Which of the following strategy will be the most appropriate to grow seedless watermelon? a) Growing triploid plant in isolation. b) Growing diploid plant with polypoid plant in the vicinity. c) Growing diploid and tetraploid plant in the vicinity. d) Growing triploid plant with diploid plant in the vicinity. 25. There are various ways which can give rise to pseudogenes. A small portion of genomic DNA is shown along with formation of pseudogenes. * A diagram showing a portion of a DNA molecule in a circular fashion. * The diagram points out that the promoter gene is followed by a gene 1. This gene is then duplicated and results in a pseudogene, followed by gene 2 and gene 3. These genes are then processed to result in another pseudogene. The processes 1, 2 & 3 responsible for the formation of pseudogenes respectively could be: a) 1: mutation 2: duplication 3: reverse transcription b) 1: duplication 2: mutation 3: reverse transcription c) 1: reverse transcription 2: mutation 3: duplication d) 1: deletion 2: duplication 3: mutation 26. The decreasing order of net primary productivity per unit area per year is: a) Estuaries> Savannah > Open ocean b) Temperate grassland > Swamp and marshes > Desert shrub c) Tropical rain forest > Open ocean >Temperate forest d) Savannah > Tundra >Estuaries 27. A student wanted to study the effect of caffeine on heart beats of _Daphnia_. Ideally, the experiment should span the entire range of concentrations that produce a response. To determine this, she performed a pilot experiment and the results obtained are shown in the graph. * A graph showing % response on the y axis and log concentration on the x axis. The graph increases from 0% to 90% at log concentration 1, and then decreases gradually to 80% at log concentration 100. Based on these results, which of the following would be the most appropriate concentration range for the actual experiment? a) Log concentration 0.001 - 0.1 b) Log concentration 0.001-10 c) Log concentration 0.001-1 d) Log concentration 0.01-100 28. Relationship between soil acidity and nitrogen fertilizers is shown in the diagram. * A diagram showing a plant with roots. The diagram shows transformation of urea (CO(NH2)2) to ammonia (NH3), then into ammonium (NH4), then into nitrate (NO3). The transformations are affected by pH. Mark the correct interpretation: a) Urea fertilizers will make soil more acidic. b) Ammonium fertilizers will have no effect on soil acidity. c) Nitrate fertilizer, if not run off, will make soil alkaline. d) Applying excess urea to soil will make soil alkaline. 29. Which of the following is/are principal mode/s of information transfer in a cell? - i. Transcription - ii. Translation - iii. Replication a) i only b) i & ii only c) ii only d) i, ii & iii 30. Which of the following vitamin protects cell against damage by reactive oxygen species? a) Riboflavin b) Ascorbic acid c) Cobalamin d) Thiamine 31. Which of the following contains amphipathic molecules that act as detergents dispersing lipids into droplets? a) Saliva b) Lymph c) Pancreatic juice d) Bile 32. Which part of the cell is in continuity with the nucleus? a) Golgi b) Mitochondria c) Endoplasmic reticulum d) Cell membrane 33. Animals exhibit responses that are mixed or intermediate between idealized regulation and idealized conformity. The osmotic pressure of the blood plasma as a function of the environmental osmotic pressure is shown for three species of marine invertebrates, the blue mussel, the green crab and grass shrimp. * A graph showing blood osmotic pressure (milliosmolarity) on the y axis and environmental osmotic pressure (milliosmolarity) on the x axis. The graph shows 3 lines: blue mussel, green crab and shrimp. The blue mussel closely follows the environmental osmotic pressure line, the green crab follows it above the environmental osmotic pressure line, and the shrimp follows a line below the environmental osmostic pressure line. *(1000 milliosmolarity is the approximate osmotic pressure of full strength sea water)* Which of the following statement/s is/are correct? - (i) Mussel is a strict osmotic conformer. - (ii) The crab regulates in water more concentrated than sea water. - (iii) The shrimp regulates over a wide range of environmental pressure. - (iv) Crab is a osmotic conformer at high environmental osmotic pressure. a) (ii) and (iii) only b) (i), (iii) and (iv) only c) (i) and (ii) only d) only (i) 34. Nisha was observing a pond sample using 15X eyepiece. She measured one of the protist using a micrometer and found it to be approximately 0.2 cm in size under the microscope. Her friend told her that the actual size of this protist is known to be 3μ. Thus Nisha was observing the organism using an objective lens of _____ magnification. a) 4X b) 10 X c) 45 X d) 100 X 35. The movement of some solutes across the membrane of the proximal tubule of the kidney is shown below. * A diagram showing a part of the proximal tubule. The diagram shows the movement of the solutes like P, Q, R, and X across the tubule, showing the direction of each movement. * NaCl is moving from the tubule into the blood. * H2O is moving from the blood into the tubule. * H is moving from the blood into the tubule. * NH3 is moving from the tubule into the blood. The modes of transport of P, Q, R, and S respectively would be: a) Active, Passive, Active, Passive b) Active, Active, Passive, Passive c) Active, Passive, Passive, Active d) Passive, Passive, Active, Active 36. Blood Ca^2+ is maintained at a level of about 10mg/100ml in a normal healthy individual. Which of the following occur when there is a drop in the blood Ca^2+ level ? - i. Stimulation of Ca^2+ uptake in kidneys. - ii. Stimulation of Ca^2+ uptake in bones. - iii. Suppression of parathyroid hormone (PTH) release. - iv. Increase in Ca^2+ uptake in intestine. - v. Vitamin D activation in liver. a) (i), (ii) and (iii) b) (iii) and (v) c) (i), (iv) and (v) d) (ii), (iii), (iv) and (v) 37. In order to study the effect of limpets and sea urchins on the seaweed survival in a particular event, the ecologist Fletcher carried out certain experiment and the effects are shown in the graph: * A graph showing seaweed cover (%) on the y axis and time (Aug 1982, Feb 1983, Aug 1983, Feb 1984) on the x axis. There are 4 lines in the graph - showing the seaweed cover under different conditions: * **Both urchins and limpets removed**: The curve increases at a steady rate from 0 to 100% * **Only limpets removed**: The curve increases steeply at the start then levels off at around 60% * **Only urchins removed**: The curve shows a gradual increase till around 40%, levels off then dips below 40% * **Both limpets and urchins present**: The curve shows a gradual increase to around 40% then levels off. - (i) Urchins had a greater effect on seaweed cover than limpets. - (ii) Removing limpets had a dramatic positive effect on seaweed growth. - (iii) Removing urchins led to increased growth of the seaweed as compared to its natural growth rate. - (iv) Both species have some influence on the seaweed distribution. a) (i) only b) (ii) and (iv) c) (iii) only d) (i) and (iv) 38. A few characteristic features of blood vessels of the human circulatory system are tabulated below: | Feature | P | Q | R | |---|---|---|---| | Blood flow| Even | Pulsatile | Even | | Presence of valves| Absent | Absent | Present | | Blood pressure| Low | High | Very low | | Elastic tissue in walls| - | +++ | + | P, Q, and R respectively represent: a) Artery, vein, capillary b) Capillary, artery, vein c) Vein, artery, capillary d) Vein, capillary, artery 39. Following is the data obtained for two fishes (1 and 2) of similar body mass: | | 1 | 2 | |---|---|---| | Heart mass (mg)| 4.7 ± 0.6 | 2.2 ± 1.1 | | Spleen mass (mg)| 14.2 ± 6 | 5.7 ± 4 | | Pectoral muscle LDH u/g | 38 ± 16 | 110 ± 42 | Which of the following is the most appropriate conclusion from the data? a) Fish 1 is benthic (bottom dwelling) while 2 is limnetic. b) Fish 1 performs endurance like activities while 2 is likely to perform short quick bursts of activities. c) Fish 2 has to supply blood to smaller biomass than fish 1. d) Fish 1 lives in well oxygenated stream while 2 lives in less aerobic environment. 40. In marine mammals, which of the following is NOT observed during deep sea diving? a) Decrease in heart rate. b) Peripheral vasoconstriction. c) Hypometabolism. d) Myoglobin saturation. 41. Enzyme 'x' is a polypeptide in nature. When added to solvent 's', it acquires following conformation- * **State A** * A diagram showing a protein in a coiled shape. * **State B** * A diagram showing a protein in a curled shape. * **State C** * A diagram showing a protein in a stretched with loops in a chain shape. Which of the following is correct? a) Enzyme will be most active in state C. b) The solvent acts as a denaturant for the protein molecule. c) Further addition of solvent will lead to precipitation of the protein. d) Further addition of solvent will lead to breaking of polypeptide bonds of the protein. 42. Which of the following correctly represents simplified model of energy and mineral movement in an ecosystem? * **Diagram a.** * A diagram showing a flow of energy from sun to producers to herbivores to decomposers to nutrient pool. * **Diagram b.** * A diagram showing a flow of energy from sun to producers to herbivores to decomposers to nutrient pool. This flow is circular. * **Diagram c.** * A diagram showing a flow of energy from sun to producers to herbivores to decomposers to nutrient pool. This flow is circular and the nutrient pool flows back to producers. * **Diagram d.** * A diagram showing a flow of energy from sun to producers to herbivores to decomposers to nutrient pool. This flow is circular and the nutrient pool flows back to producers. 43. Various communities can be classified based on their metabolic characteristics such as productivity and respiration. Communities P, Q, and R in the graph respectively represent: * A graph showing community production (gm/m²/day) on the y axis and community respiration (gm/m²/day) on the x axis. There are 3 dots representing different communities - P, Q, and R. P has the highest community respiration and lowest community production, followed by Q and then R. a) oceans, deserts and ponds. b) coral reefs, deserts and fertile agricultural area. c) estuaries, oceans and grassland. d) oceans, swamp waters and coral reefs. 44. Generalized profile of a soil in which a plant is growing is shown. * A diagram showing a soil profile. The soil is divided into 5 layers - P, Q, R, S, and T. The region/s rich in humus will be: a) P only. b) P and Q. c) R only. d) S only. 45. The following represents a tri-peptide (3 amino acids) stretch of a protein sequence: **Arginine-Methionine-Lysine** Given below are four DNA sequences. Only one strand of the double-stranded DNA has been represented. Which one of the following can possibly code for the above tri-peptide? a) 5' AAA GTA CGC 3' b) 5' TTT CAT GCG 3' c) 5' GCG TAC TTT 3' d) 5' CGC AUG AAA 3' 46. In a diploid organism the total DNA content of a sperm was found to be ‘C’. What will be the DNA content of its cell that is at Metaphase I of meiosis? a) C b) 0.5C c) 2C d) 4C 47. In a plant, the color of a flower is determined by the conversion of a white pigment into a red pigment that is controlled by the product of gene 'B'. Product of the gene 'A' is responsible for bringing the white pigment into the cell for conversion. The process is schematically represented in the figure. * A diagram showing a white pigment being converted to red pigment. * Gene A and Gene B are responsible for controlling the conversion. * Allele a and allele b are non-functional mutant alleles of genes A and B. Alleles 'a' and 'b' are non-functional mutant alleles of genes 'A' and 'B', respectively. Two parental plants with white flowers are crossed. F1 progeny have red flowers only. When the F1 progeny is self-pollinated, the F2 progeny has plants that have either red or white flowers. Considering that the two genes are on two independent chromosomes, what is the expected ratio of the two phenotypes in the F2 progeny? a) 3 Red: 1 white b) 9 Red: 7 white c) 1 Red: 1 white d) 15 Red: 1 white 48. The following pedigree represents the inheritance of a rare disorder caused due to an autosomal recessive allele. Filled square indicates affected male. * A pedigree chart showing 3 generations: * 1st Generation - 2 parents. * 2nd Generation - 2 children (one girl unaffected, one boy affected). * 3rd Generation- one girl. What is the probability that the daughter in the third generation carries the allele responsible for the disorder? a) 1/2 b) 2/3 c) 3/4 d) 1/4 49. Bacteriophages are viruses that infect bacterial cells... In a given experiment bacteriophages were grown in the presence of radioisotopes 14C and 32P. These bacteriophages were used to infect bacterial cells. Following infection, radioisotopes present in the bacterial cells were analyzed. The radioactivity in the bacterial cell will be observed due to the presence of: a) Only 32P b) Only 14C c) Both 32P and 14C d) Either 32P or 14C 50. A water strider can walk on the surface of water without even getting its claws wet. The insect can do it due to which property of water? a) Specific gravity c) Specific heat b) Surface tension d) Anomalous behaviour 51. The spider silk has a predominant component called 'spiderwin', with five times the strength of steel, weight for weight. The elasticity of the web strands is due to the presence of: a) beta sheets c) disordered loops b) alpha helices d) sugar residues 52. The hepatocytes of an elephant, in comparison to the hepatocytes of a mouse are: a) twice as big. c) twenty times bigger. b) five times bigger. d) of the same size. 53. Plant scientists are worried that C4 crops such as corn and sugarcane may suffer stiffer competition from C3 weeds since there is a global _____. a) increase in temperature. c) decrease in rainfall. b) increase in CO2 content of atmosphere. d) increase in genome contamination of C4 crops. 54. During menstrual cycle there are two surges in estrogen concentration of blood. The first and major surge is just prior to the ovulation phase and the next one is in: a) menstruation phase b) early follicular phase c) mid- luteal phase d) late- luteal phase 55. Match the following examples with the evolutionary phenomena, namely, convergent evolution (p), divergent evolution (q), and adaptive radiation (r). - i. Sugar gliders of Australia and European flying squirrel. - ii. Squirrel species on opposite rims of Grand Canyon. - iii. Sharks and dolphins. - iv. Darwin's finches. a) i-p, ii- q, iii-p, iv- r b) i- r, ii- r, iii-p, iv- r c) i-r, ii- q, iii- p, iv- q d.) i- q, ii- r, iii-p, iv- p 56. Most of the drugs are eliminated by nephrons through: a) Filtration at loop of Henle. b) tubular reabsorption at proximal convoluted tubules. c) tubular secretion at distal convoluted tubules. d) tubular secretion at collecting duct. 57. Consumption of salty food results in increased thirst and a cascade of events. Select and arrange the sequence of events: - i) Increased reabsorption of water. - ii) High Nat in blood - iii) Increased release of aldosterone. - iv) Increased ADH in blood. - v) Passing out more concentrated urine. Choose the correct sequence. a) ii, iv, i, v b) i, iii, iv, ii, v. c) iii,i, iv, v, iid) ii, iii, vi, i. 58. Acid precipitation refers to rain, snow or fog with a pH lower or more acidic than pH 5.6. It results primarily by the presence of which of the following components in the atmosphere? a) CO and CO2 c) lead and phosphorous oxides b) sulphur and nitrogen oxides d) ozone and hydrocarbons 59. Peroxisomes are often noticed in proximity of mitochondria. This is due to the fact that the products can be transported to mitochondria. Which of the following functions is most relevant to this explanation? a) Peroxisomes use oxygen to break fatty acids down into smaller molecules that are then used as fuel for cellular respiration. b) Peroxisomes oxidise alcohol to detoxify it in liver. c) Perox