Science (086) — AI-generated practice question

The decision to withdraw the hand is made in the spinal cord, not the brain. When we touch a hot object, the input nerve (detecting heat) and the output nerve (moving muscles) are connected directly in the spinal cord through a reflex arc, without waiting for signals to travel all the way to the brain.

This is advantageous because sending signals to the brain for conscious thinking takes too long — enough time to cause serious burns. The spinal cord reflex arc allows a much faster response, protecting the body from injury. The pain signal does reach the brain, but only after the hand has already been withdrawn.

Source: Chapter 6, Section 6.1.1 – Reflex Actions

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Examiners look for three things here (1 mark each):

1. Location — spinal cord (via reflex arc), not the brain.
2. Mechanism — input and output nerves are connected in the spinal cord directly, bypassing the brain for the motor response.
3. Advantage — speed; brain processing is too slow and could result in greater injury.

Remember: the brain does receive the pain signal eventually — that's why you feel pain after withdrawal. This nuance shows deeper understanding but is secondary to the three core points above.