Question Bank — Life Processes

QUESTION BANK: Life Processes (NCERT Chapter 5)

Section A — MCQs (10 questions, 1 mark each)

1. Which of the following best explains why diffusion alone cannot meet the oxygen needs of a multicellular organism like a human?
(a) Oxygen molecules move too slowly in air
(b) Most body cells are not in direct contact with the external environment
(c) Oxygen is only required by the lungs
(d) Carbon dioxide blocks diffusion pathways

2. In an experiment, a variegated leaf is tested for starch after exposure to sunlight. Only the green areas turn blue-black with iodine. This observation indicates that:
(a) Chlorophyll is necessary for starch formation
(b) Sunlight is not required for photosynthesis
(c) Starch is formed only in non-green parts
(d) Water is the only raw material needed

3. Assertion (A): Guard cells regulate the opening and closing of stomata.
Reason (R): When guard cells swell due to water entry, the stomatal pore opens.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true

4. The process in which pyruvate is converted to lactic acid in human muscle cells occurs when:
(a) Sufficient oxygen is available
(b) Oxygen supply is insufficient during sudden activity
(c) Only anaerobic respiration takes place in mitochondria
(d) Glucose breakdown stops completely

5. Assertion (A): The left ventricle of the human heart has thicker muscular walls than the left atrium.
Reason (R): Ventricles have to pump blood to all parts of the body under higher pressure.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true

6. Which component of blood is primarily responsible for preventing loss of blood pressure after an injury?
(a) Plasma proteins
(b) Red blood corpuscles
(c) Platelet cells
(d) White blood corpuscles

7. In plants, the upward movement of water and minerals through xylem is mainly driven by:
(a) Root pressure alone during the day
(b) Transpiration pull created by evaporation from leaves
(c) Active transport by phloem companion cells
(d) Diffusion from soil directly into leaves

8. The inner lining of the small intestine has finger-like projections called villi. Their main function is to:
(a) Secrete bile for fat emulsification
(b) Increase surface area for absorption of digested food
(c) Produce hydrochloric acid
(d) Store undigested food temporarily

9. Which of the following correctly shows the sequence of events in aerobic respiration in humans?
(a) Glucose → Pyruvate (cytoplasm) → CO₂ + H₂O + energy (mitochondria)
(b) Glucose → Ethanol + CO₂ (mitochondria)
(c) Pyruvate → Lactic acid (cytoplasm only)
(d) Glucose → Starch (chloroplast)

10. Plants can get rid of excess water and some waste products through:
(a) Active transport into root hairs only
(b) Transpiration and storage in vacuoles or falling leaves
(c) Diffusion through stomata of oxygen alone
(d) Conversion into glycogen in phloem

Section B — Very Short Answer (6 questions, 2 marks each)

11. Why do desert plants take up carbon dioxide at night and store it as an intermediate compound?

12. State two functions of mucus secreted in the human stomach.

13. How does the presence of rings of cartilage in the human throat help in respiration?

14. Differentiate between the role of xylem and phloem in the transport of substances in plants (two points).

15. What is the role of bile salts in the digestion of fats?

16. Why is it necessary for the human body to remove nitrogenous wastes such as urea from the blood?

Section C — Short Answer (5 questions, 3 marks each)

17. Describe the role of stomata in gaseous exchange and transpiration in plants. How do guard cells control their opening and closing?

18. Explain why the small intestine is longer in herbivores than in carnivores. How does its internal structure aid absorption of digested food?

19. Draw a neat labelled diagram of the human excretory system. Label: kidney, ureter, urinary bladder and urethra.

20. What are the differences between aerobic and anaerobic respiration in terms of location, products and amount of energy released? Give one example of an organism that shows anaerobic respiration.

21. How do plants obtain nitrogen and other minerals from the soil? Why is nitrogen essential for plants?

Section D — Long Answer (3 questions, 5 marks each)

22. Describe the process of nutrition in Amoeba with the help of a labelled diagram. How does it differ from nutrition in Paramecium?

23. Draw a neat labelled diagram of the human heart showing the direction of blood flow. Explain double circulation in humans and why it is necessary in birds and mammals.

24. (a) Describe the structure of a nephron with a labelled diagram.
(b) Explain how urine is formed and how the amount of urine produced is regulated.

Section E — Case/Source-Based (2 questions, 4 marks each)

25. Case: A student sets up two potted plants under bell jars. One jar has a watch-glass containing potassium hydroxide placed near the plant; the other does not. Both are kept in sunlight for two hours. Leaves from both plants are then tested for starch with iodine.
(a) What is the role of potassium hydroxide in this setup? (1)
(b) Predict the result of the starch test for each plant and give reason. (1)
(c) Which raw material of photosynthesis is being tested here? (1)
(d) Why was the plant kept in darkness for three days before the experiment? (1)

26. Case: During a sports activity, an athlete suddenly develops muscle cramps. The coach explains that this occurs due to accumulation of a certain substance in muscle cells.
(a) Name the substance that accumulates and the process responsible. (1)
(b) Under what condition does this pathway become active? (1)
(c) How is this different from the normal pathway of glucose breakdown in muscle cells? (1)
(d) What is the effect on energy release when this pathway operates? (1)

Section F — HOTS and Application (4 questions, 3 marks each)

27. Predict-and-justify: What would happen to the rate of breathing in a fish if it is transferred from a well-aerated pond to a stagnant pond with very low dissolved oxygen? Justify your answer.

28. Analyse anomalous observation: In an experiment, a leaf is plucked from a plant kept in sunlight, boiled in alcohol and tested with iodine. Only a few patches turn blue-black even though the leaf was green. Give a possible scientific reason for this unexpected result.

29. Apply to real-life situation: A person living at high altitude (low oxygen) shows increased breathing rate and higher haemoglobin levels after a few weeks. Explain the physiological adjustments using concepts from the chapter.

30. Compare two situations: Compare the outcome in two plants — one with all stomata permanently closed during the day and another with stomata opening normally. Which plant is likely to survive longer in bright sunlight and why?