Q1. [5] deep thorough-understanding
A mountaineer stranded in extreme cold notices his heart is racing, his digestion has slowed, and he is breathing faster, even though he is sitting still.
(i) Name the hormone responsible for this state and the gland that secretes it.
(ii) Explain how each of the three physiological changes — increased heart rate, slowed digestion, and faster breathing — helps him survive the emergency.
(iii) Once he is rescued and safe, his body gradually returns to normal. What does this suggest about how hormone action is regulated after the emergency has passed?
Generated by claude-sonnet-4-6 · 2026-06-26 01:03 · grounding rag
Model Answer
(i) The hormone responsible is adrenaline, secreted by the adrenal glands.
(ii)
- Increased heart rate: Adrenaline makes the heart beat faster, supplying more oxygen to the muscles, preparing the body for immediate action (fight or flight).
- Slowed digestion: Blood supply to the digestive system is reduced due to contraction of muscles around small arteries, diverting blood to skeletal muscles where it is needed most.
- Faster breathing: Contractions of the diaphragm and rib muscles increase breathing rate, ensuring more oxygen enters the body to meet the increased demand.
(iii) Once the emergency is over, hormone secretion is regulated by a feedback mechanism. As adrenaline levels normalise and the body stabilises, its further secretion is reduced. This shows that the timing and amount of hormone released are controlled by feedback, preventing over- or under-response.
Source: Chapter 6, Section 6.3 — Hormones in Animals
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Explanation
- Examiners expect you to name both the hormone and the gland for full marks in part (i).
- In part (ii), link each change directly to survival benefit — don't just state the change; explain why it helps.
- Part (iii) is testing your knowledge of feedback mechanism — the key term examiners look for. Use the insulin-blood sugar example from the text as your model, applied here to adrenaline.
- Keep each point concise; one sentence per physiological change is sufficient.