India 2014 — inbo2014-Q.pdf

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Problema 1

CELL BIOLOGY (6 points)

1 INDIAN NATIONAL BIOLOGY OLYMPIAD – 2014 SECTION A

CELL BIOLOGY (6 points)

1. (1 point) Many molecules are chiral i.e. their mirror images are nonsuperimposable. Which of the following could be affected if the chirality of a molecule is changed in a biological system? I. Taste reception II. Smell perception III. Toxicity IV. Mode of action a. I and II only b. I, II and III only c. III and IV only d. I, II, III and IV

2. (1 point) In order to increase the excitability of a patch of neuronal cell membrane: a. the number of Na+ and K+ channels should be increased . b. the capacitance of the membrane should be increased. c. the thickness of the membrane should be reduced. d. the content of charged lipids in the membrane should be increased.

3. (1 point) The best exercise regimen to lose excess body fat is the one which: a. exercises as many muscles as possible. b. results in very little shortness of breath. c. results in shortness of breath with profuse sweating. d. stresses and compresses body regions that store most of the fat.

4. (1 point) Lips are more sensitive to temperature or touch than forearm skin. This is because of the: a. higher frequency of action potentials.

2 b. greater height of the action potential. c. faster transmission of the action potential. d. larger number of neurons stimulated in the CNS.

5. (1 point) A cell has a fixed number of adenine nucleotides. Each of these adenine nucleotides will be in monophosphate (AMP), diphosphate (ADP) or triphosphate (ATP) form. Adenine nucleotides are constantly interconverted from one form to another due to the metabolic activities of the cell as shown below:

One of the key enzymes in this interconversion is adenylate kinase which catalyzes the following reaction: ATP + AMP ⇄ 2ADP Of the three forms, hydrolysis of only the triphosphate form (i.e., ATP) results in energy that can be used to perform “work” by the cells. Which one of the following ratios best describes the energy potentially available to a cell?

a.

AMP ADP ATP ATP

b.

AMP ADP ATP ADP 2 1 ATP

c.

AMP ADP ATP ADP ATP

3 d.

AMP ADP ATP ADP 2 ATP

6. (1 point) There are various types of ATPase pumps found in different types of cells. Of these, F-type ATPases, also known as ATP synthases, drive ATP synthesis. They are found in all of the following EXCEPT: a. inner membrane of mitochondria. b. thylakoid membrane of chloroplasts. c. plasma membrane of prokaryotes. d. plasma membrane of fungi.

PLANT SCIENCES (10 points)

7. (1 point) Lignin is a secondary metabolite found in plants. Which of the following statement/s about this biomolecule is/are true? I. It is the most abundant organic compound on the earth. II. In many plants, lignin is sequestered in vacuoles in order to protect other compounds of the cell. III. It waterproofs the cell wall and helps in transportation of water in terrestrial plants. IV. Lignin is structurally very similar to tannins and like tannins, it is also an important deterrent to herbivores. a. I, II and III b. II and IV c. Only III d. I, III and IV

8. (1 point) Study the photosynthetic pathway given. A few statements are made about this pathway. Choose the appropriate one.

4

a. The pathway represents the cyclic photosynthesis that occurs in plants and algae. b. The pathway represents the anoxygenic photosynthesis that is found in bacteria. c. The pathway indicates photosynthesis of cyanobacteria but is erroneous as it does not show synthesis of NADPH. d. The pathway indicates cyclic photosynthesis involving photosystem I that is found in plants as well as bacteria.

9. (1 point) In an experiment, the stem of a tomato plant was wounded in such a way that portions of vascular bundles were removed. After the experiment, which of the following will delay the recovery of the wounded tissue the most by cutting off supply of cytokinins? a. Cutting the young leaves and buds above the wound. b. Removing the flowers and leaves below the wound. c. Cutting the growing root tips and tilting the plant. d. Cutting the mature and senescing leaves below as well as above the wound.

10. (1 point) Several experiments have been done to find how the ions enter the mature vessels or tracheids of xylem. In one study, it was found that cells of pea (Pisum sativum) roots had K+ ion concentration 75 times greater than that of the nutrient solution. In another study, it was found that the rate of $h\upsilon$ -1.2 +0.4 Em (volts) (P870)* (P870) QA UQ Cyto C1 QB Cyto C2 Proton flow H+ H+

5 phosphate absorption gradually reached zero over 4 days of continuous darkness. Which of the following can be deduced from these experiments? a. Ion uptake by plants is an active process. b. Ion uptake is a passive process but requires carrier proteins. c. Ion uptake is a light-driven process and transpirational pull plays an important role in it. d. The two experiments cannot be compared as the ions studied in them are different.

11. (1 point) Ectomycorrhiza – a symbiotic association between plant roots and fungi is important in obtaining phosphorus and other nutrients for the plant. Which of the following points characterize the relationship?
12. Penetration of host cell by fungal hyphae.
13. Creation of a vast network of hyphae to absorb nutrients.
14. Change in soil pH.
15. Movement of organic carbon to fungi.

a. 1, 2, 3 and 4 b. Only 1, 2 and 3 c. Only 2 and 3 d. Only 2, 3 and 4

12. (1 point) What would be the water potential $(\text{Psiw}$), solute potential $(\text{Psis}$) and pressure potential $(\text{Psip}$) at equilibrium when a cell with $\text{Psis}=$ – 0.7 MPa and $\text{Psip}=$ 0.7 MPa is placed in a solution with $\text{Psis}=$ – 0.5 MPa? a. $\text{Psiw}=$ – 0.2 MPa, $\text{Psis}=$ – 0.5 MPa, $\text{Psip}=$ – 0.5 MPa b. $\text{Psiw}=$ – 0.5 MPa, $\text{Psis}=$ – 0.7 MPa, $\text{Psip}=$ 0.2 MPa c. $\text{Psiw}=$ – 0.5 MPa, $\text{Psis}=$ – 0.5 MPa, $\text{Psip}=$ 0 MPa d. $\text{Psiw}=$ – 0.3 MPa, $\text{Psis}=$ – 0.3 MPa, $\text{Psip}=$ 0 MPa

6 13. (1 point) Heterospory is evolutionarily advanced feature over homosporous condition which first appeared in pteridophytes. Which of the following cycles correctly describes this feature in ferns?

14. (1 point) In a laboratory experiment, with a particular pteridophyte, a normal diploid sporophytic plant was grown in a poor nutrient medium without sucrose. The gametophyte obtained was grown in a normal nutrient medium. Some sporophytes obtained from such gametophytes were later observed to be tetraploids. What may be the possible reason for this? Meiosis Fertilization Antheridium Archegonium Microgametophyte Megagametophyte egg sperm zygote Embryo Sporophyte Megasporangium Spore mother cell b. microsporangium Spore mother cell Meiosis Fertilization Microspore Megaspore Microgametophyte Megagametophyte egg sperm zygote Embryo Sporophyte Megasporangium Spore mother cell c. microsporangium Spore mother cell Meiosis Fertilization Megaspore Microspore Megagametophyte Microgametophyte Sperm Egg zygote Embryo Sporophyte Sporangium Spore mother cell a. Meiosis Fertilization spore Archegonium Antheridium Sperm Egg zygote Embryo Sporophyte Sporangium Spore mother cell d. gametophyte

7 a. The poor nutrient medium caused apospory to occur. b. The poor nutrient medium caused apogamy to occur. c. The sucrose deficient medium induced fusion of more than two gametes. d. It is random mutation and sucrose deficient nutrient medium has no role to play.

15. (1 point) Capsules/sporangia of sporophytes of some bryophytes and pteridophytes produce elaters (kind of sterile cells) in addition to the spores. What may be the probable major role played by them? a. Dispersal of spores. b. Provision of reserve food to the developing spores. c. Protection of immature spores. d. Providing moisture to the developing spores.

16. (1

Topic: Conservation of Energy, Oscillations & Waves, Thermodynamics Metodi: Energy Conservation Method, Conservation Laws, Simple Harmonic Motion Analysis, Wave Equation Competenze: Physical Reasoning Fonte: Testo (PDF) — p.1