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CIE iGCSE Co-Ordinated Science B13.3 Homeostasis Exam Style Questions Paper 1

CIE iGCSE Co-Ordinated Science Paper 1 - All Chapters

Question

The diagram shows a section through the skin.

Which row contains the correct names of the structures labelled P, Q and R?

▶️ Answer/Explanation
P is a sweat gland, which releases sweat onto the skin surface for evaporative cooling.
Q is a hair, which traps an insulating layer of air close to the skin when erect.
R is an erector muscle, which contracts to pull the hair upright in cold conditions.
✅ Answer: (C)

Question

A person leaves an air conditioned building.

The temperature of the air conditioned building is 16°C.
The outside temperature is 39°C.

Which statement describes one response to the change in temperature?

A. The blood detects the change in temperature and the person starts to shiver.
B. The blood detects the change in temperature and the person starts to sweat.
C. The brain detects the change in temperature and the person starts to shiver.
D. The brain detects the change in temperature and the person starts to sweat.

▶️ Answer/Explanation
Changes in body temperature are detected by the thermoregulatory centre in the brain, not directly sensed by the blood itself.
Moving from a cool 16°C room into a hot 39°C environment causes the body to sweat, cooling it through evaporation.
✅ Answer: (D)

Question

The graph shows the variation of body temperature over time of a healthy person at rest.

How will the body reverse the temperature change shown between times X and Y?

A. decreased breathing rate
B. decreased pulse rate
C. shivering
D. sweating

▶️ Answer/Explanation
Between X and Y, body temperature rises above the normal set point.
Sweating cools the body because heat is used to evaporate water from the skin surface.
Decreased breathing rate, decreased pulse rate and shivering would not lower body temperature in this way.
✅ Answer: (D)

Question

The diagram shows a section through the skin.

Which labelled structures help to maintain body temperature in the cold?

A. 1 and 3
B. 1 and 4
C. 2 and 3
D. 3 and 4

▶️ Answer/Explanation
In cold conditions, blood vessels near the skin surface constrict (vasoconstriction) to reduce heat loss by directing blood flow deeper into the body.
Hair erector muscles also contract, pulling hairs upright to trap an insulating layer of air near the skin surface.
The two labelled structures corresponding to a constricted blood vessel and an erected hair are the ones that help retain heat in the cold.
✅ Answer: (A)
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