Biology · Sample Paper 1

General instructions

Section A · Objective

1. Question 11 mark

   Which is a defining property of living organisms?

   1. A.growth
   2. B.reproduction
   3. C.cellular organisation
   4. D.movement
2. Question 21 mark

   Methanogens belong to

   1. A.eubacteria
   2. B.archaebacteria
   3. C.cyanobacteria
   4. D.mycoplasma
3. Question 31 mark

   The main plant body of a moss is

   1. A.sporophyte
   2. B.gametophyte
   3. C.prothallus
   4. D.protonema only
4. Question 41 mark

   Which animal has a water vascular system?

   1. A.Hydra
   2. B.starfish
   3. C.earthworm
   4. D.Ascaris
5. Question 51 mark

   Axile placentation is seen in

   1. A.pea
   2. B.mustard
   3. C.China rose
   4. D.Dianthus
6. Question 61 mark

   Ribosomes in prokaryotes are of the type

   1. A.70S
   2. B.80S
   3. C.60S
   4. D.90S
7. Question 71 mark

   Which bond links amino acids in a protein?

   1. A.glycosidic
   2. B.peptide
   3. C.phosphodiester
   4. D.hydrogen
8. Question 81 mark

   Crossing over takes place during

   1. A.leptotene
   2. B.zygotene
   3. C.pachytene
   4. D.diakinesis
9. Question 91 mark

   The first stable product of the C₄ pathway is

   1. A.PGA
   2. B.oxaloacetic acid
   3. C.RuBP
   4. D.malic acid
10. Question 101 mark

    Glycolysis takes place in the

    1. A.mitochondrial matrix
    2. B.cytoplasm
    3. C.inner membrane
    4. D.chloroplast
11. Question 111 mark

    Most CO₂ is carried in blood as

    1. A.carbaminohaemoglobin
    2. B.dissolved CO₂
    3. C.bicarbonate
    4. D.carbonic acid
12. Question 121 mark

    Which hormone lowers blood glucose?

    1. A.glucagon
    2. B.insulin
    3. C.adrenaline
    4. D.cortisol
13. Question 131 mark

    Assertion (A): The SA node is called the pacemaker of the heart.

    Reason (R): The SA node generates the maximum number of action potentials per minute.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
14. Question 141 mark

    Assertion (A): Ethylene is used to ripen fruits.

    Reason (R): Ethylene is a gaseous plant growth regulator.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
15. Question 151 mark

    Assertion (A): Birds excrete uric acid.

    Reason (R): Uric acid can be removed with very little water loss.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
16. Question 161 mark

    Assertion (A): In a resting neuron, the inside of the axon is negatively charged.

    Reason (R): The axonal membrane is more permeable to Na⁺ than to K⁺ at rest.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.

Section B · Very short answer

1. Question 172 marks

   Give two rules of binomial nomenclature with an example.

2. Question 182 marks

   Differentiate between heartwood and sapwood.

3. Question 192 marks

   Name the three types of cell junctions and state the role of each.

4. OR

   Question 192 marks

   What are viroids? How do they differ from viruses?

5. Question 202 marks

   What happens to the A band and I band of a sarcomere during muscle contraction?

6. Question 212 marks

   Define respiratory quotient. What is its value for carbohydrates and for fats?

Section C · Short answer

1. Question 223 marks

   Compare the three classes of algae on the basis of pigments, stored food and one example each.

2. Question 233 marks

   Describe the fluid mosaic model of the plasma membrane. Mention two functions of the membrane.

3. Question 243 marks

   What is competitive inhibition? Give an example. How does temperature affect enzyme activity?

4. Question 253 marks

   What is photorespiration? Why doesn't it occur in C₄ plants?

5. Question 263 marks

   Explain the ABO blood group system. Why is O called the universal donor?

6. OR

   Question 263 marks

   Describe the counter-current mechanism in the kidney and its importance.

7. Question 273 marks

   Describe how a nerve impulse is transmitted across a chemical synapse.

8. Question 283 marks

   Define tidal volume, vital capacity and residual volume, with approximate values in a healthy adult.

Section D · Case-based

1. Question 294 marks

   Case study — A swelling in the neck. A woman from a hilly region has a visible swelling in the front of her neck. Her doctor says her diet lacks iodine and that the thyroid gland has enlarged.

   (i) Name the condition. (1 mark)

   (ii) Why is iodine needed by the thyroid gland? (1 mark)

   (iii) Name two hormones of the thyroid and one function of each. (2 marks)

   OR

   (iii) What happens if a child is born with too little thyroid hormone? (2 marks)

2. Question 304 marks

   Case study — Growing seedless grapes. A grape farmer sprays a growth regulator to make bunches longer and grapes bigger. A sugarcane grower uses the same regulator to raise yield, and a brewery uses it to speed up malting.

   (i) Name the growth regulator. (1 mark)

   (ii) How does it increase sugarcane yield? (1 mark)

   (iii) Name another PGR and give two of its uses. (2 marks)

   OR

   (iii) What is apical dominance? Which PGR controls it? (2 marks)

Section E · Long answer

1. Question 315 marks

   Describe the events of the four stages of mitosis with diagrams. State two significances of mitosis.

2. Question 325 marks

   Describe the Krebs cycle with its main steps. Where does it occur? Calculate the net ATP produced from one glucose molecule in aerobic respiration.

3. Question 335 marks

   Describe the cardiac cycle. What do the P, QRS and T waves of an ECG represent? Calculate the cardiac output if heart rate is 72/min and stroke volume is 70 mL.

4. OR

   Question 335 marks

   Give five characteristic features of class Mammalia with one example each of an egg-laying, a flying and an aquatic mammal.