Negative feedback
Exam-ready definition
A control mechanism in which a change in a condition triggers a response that reverses the change, returning the condition to its set point. The basis of homeostasis.
How this is marked
Extended-only language. The mark scheme wants the reversal idea stated explicitly: the response counteracts the original change. Use insulin/glucagon or sweating/shivering as your worked example.
In an exam answer
For blood glucose control: 'A rise in blood glucose triggers insulin release, which lowers it again. The response reverses the change, which is negative feedback.'
Full topic guide: Coordination & response
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