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Homeostasis: temperature regulation — KCSE Biology

KCSE Biology · 80 practice questions · 3 syllabus objectives

32 easy25 medium23 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Explain how the body maintains a constant temperature

Distinguish between ectotherms and endotherms

Homeostasis: temperature regulation

Sample Questions

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1
easySHORT ANSWER4 marks

Distinguish between an ectotherm and an endotherm in terms of body temperature regulation. Give one named example of each.

View Marking Scheme
Part (a) — 4 marks
Ectotherm defined correctly (1 mk)
Endotherm defined correctly (1 mk)
Correct named example of ectotherm — 0. (1 mk)
Correct named example of endotherm — 0.5 mark (or 1 mark each) (1 mk)
2
easySHORT ANSWER5 marks

The ability of organisms to maintain a stable internal environment is crucial for survival, particularly in response to varying external temperatures. This includes various adaptations and physiological mechanisms that contribute to effective temperature regulation. (a) Explain how a hairy body helps an organism maintain its body temperature above that of the environment during cold conditions. (3 marks) (b) State the role of the erector pili muscle in temperature regulation. (1 mark) (c) Identify the role of adipose (fat) tissue found beneath the skin in temperature regulation. (1 mark)

View Marking Scheme
Part (a) — 3 marks
In cold conditions, the erector pili muscles contract, causing the hair to stand erect/upright; (1 mk)
The erect hair traps a thick layer of still air next to the skin surface; (1 mk)
Air is a poor conductor of heat, so the trapped air acts as an insulating layer; reducing heat loss from the body by convection and radiation; (1 mk)
Part (b) — 1 mark
In cold: contracts to raise hair for insulation; In hot: relaxes so hair lies flat, reducing the insulating air layer to allow more heat loss; (1 mk)
Part (c) — 1 mark
Adipose tissue acts as an insulating layer beneath the skin; it reduces heat loss from the body to the environment; (1 mk)
3
easySHORT ANSWER4 marks

Distinguish between an ectotherm and an endotherm in terms of source of body heat. Give one named example of each.

View Marking Scheme
Part (a) — 4 marks
Ectotherm defined correctly (1 mk)
Endotherm defined correctly (1 mk)
Correct named example of ectotherm — 0. (1 mk)
Correct named example of endotherm — 0.5 mark (or 1 mark each) (1 mk)
4

Name one common example of an ectotherm and one of an endotherm. (2 marks)

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