When you accidentally touch a hot object, why is the response carried out without waiting for the brain to th…

Question

When you accidentally touch a hot object, why is the response carried out without waiting for the brain to think about it? Explain the advantage this gives.

Accepted Answer

## Model Answer When we touch a hot object, the response is carried out by a **reflex arc** — a nervous pathway connecting sensory nerves to motor nerves through the **spinal cord**, without involving the brain. The nerve that detects heat connects directly to the nerve that moves the muscle, right at the spinal cord. This means the signal does not travel all the way up to the brain and back, saving time. **Advantage:** Brain thinking involves complex interactions of many neurons, which takes time. During this delay, the hand could get seriously burnt. The reflex arc allows a much faster response, protecting the body from injury. *Source: Chapter 6, Section 6.1.1 – Reflex Actions* --- ## Explanation - Examiners look for three things: (1) **what** happens (reflex arc via spinal cord), (2) **why** it is fast (bypasses brain), and (3) the **advantage** (prevents greater injury/burn). - Don't just say "it's automatic" — name the **reflex arc** and **spinal cord** for full marks. - One mar…

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