Q1. [3] medium thorough-understanding
Classify the following actions as voluntary or involuntary, and for each involuntary action, name the specific part of the nervous system that controls it: (i) writing an answer in an exam, (ii) sneezing when dust enters the nose, (iii) maintaining balance while climbing stairs, (iv) increased heart rate during exercise.
Generated by claude-sonnet-4-6 · 2026-06-26 01:01 · grounding rag
Model Answer
| Action | Type | Controlling Part |
|---|---|---|
| (i) Writing an answer | Voluntary | Fore-brain (cerebrum) |
| (ii) Sneezing | Involuntary | Medulla in the hind-brain |
| (iii) Maintaining balance on stairs | Involuntary | Cerebellum (hind-brain) |
| (iv) Increased heart rate | Involuntary | Medulla in the hind-brain |
Writing is a thought-out voluntary action controlled by the fore-brain. Sneezing and heart rate changes are involuntary actions controlled by the medulla. Balance and posture are maintained by the cerebellum, which ensures precision of voluntary actions.
Source: Control and Coordination, Section 6.1.2 Human Brain
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Explanation
- Examiners expect correct classification and the specific brain region for each involuntary action — both parts are needed for full marks.
- A common mistake is saying the "brain" controls balance; you must name cerebellum specifically.
- Sneezing may seem like a reflex, but the question asks for the involuntary control centre — the medulla controls involuntary actions like salivation, vomiting, and sneezing.
- "Voluntary" actions need no brain-part name; only involuntary ones require it as per the question.