Science — CBSE Class 10 board question

(a) Voluntary vs. Involuntary Action:

| Voluntary Action | Involuntary Action |
|---|---|
| Controlled by thinking; decision is made consciously. | Occurs without conscious thought or control. |
| Controlled by the fore-brain. | Controlled by mid-brain and hind-brain (medulla). |
| Examples: writing, walking, clapping. | Examples: heartbeat, salivation, blood pressure. |

(b) Reflex Action:

Reflex action is a sudden, automatic response to a stimulus that occurs without conscious thinking. It is a quick response controlled by the spinal cord through a reflex arc.

Flow diagram of the nerve impulse path:

$$\text{Stimulus} \rightarrow \text{Receptor} \rightarrow \text{Sensory Nerve} \rightarrow \text{Spinal Cord (Reflex Arc)} \rightarrow \text{Motor Nerve} \rightarrow \text{Effector (Muscle)} \rightarrow \text{Response}$$

(Information also travels from the spinal cord to the brain, but the response is initiated at the spinal cord itself.)

Source: Chapter 6, Sections 6.1.1 and 6.1.2

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• (a): Examiners expect at least 2–3 clear points of difference, ideally in a table. Key distinction: voluntary = brain (fore-brain) + thinking; involuntary = mid/hind-brain, no thinking.
• (b): Define reflex action clearly (sudden, without thinking, via spinal cord). The flow diagram must show the correct sequence: Stimulus → Receptor → Sensory nerve → Spinal cord → Motor nerve → Effector → Response. Many students forget to mention that the impulse also reaches the brain, but the response originates at the spinal cord — include this for full marks.