GCSERevise
AQASpec 4.5Foundation & Higher~35 min

Homeostasis & Response

Biology · Topic revision workspace

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Topic overview

What you need to know

Homeostasis & Response is a key part of GCSE Biology. Connect structures to their functions and explain biological processes as clear causal sequences. The maintenance of a constant internal environment in response to internal and external changes. A control mechanism where a change in a condition triggers a response that reverses the change, returning to the optimum. Maintaining body temperature at about 37°C. Controlled by the thermoregulatory centre in the brain (hypothalamus).

Exam tip

Use precise scientific vocabulary and make each link in an explanation explicit.

Revision notes

Core ideas

Secure these ideas first. Say each definition in your own words, then connect it to the topic overview.

  • Homeostasis: The maintenance of a constant internal environment in response to internal and external changes.
  • Negative Feedback: A control mechanism where a change in a condition triggers a response that reverses the change, returning to the optimum.
  • Thermoregulation: Maintaining body temperature at about 37°C. Controlled by the thermoregulatory centre in the brain (hypothalamus).
  • Vasoconstriction: Blood vessels near the skin surface narrow to reduce blood flow and heat loss when the body is too cold.

Revision notes

Apply it in the exam

The exam will rarely ask for an isolated definition. Practise selecting the right idea and using it as part of a complete explanation or method.

  • Vasodilation: Blood vessels near the skin surface widen to increase blood flow and heat loss when the body is too hot.
  • Blood Glucose Regulation: Controlled by the pancreas: insulin lowers blood glucose (stores as glycogen), glucagon raises it (breaks down glycogen).
  • Insulin: A hormone produced by the pancreas that causes cells to take up glucose from the blood and the liver to convert glucose to glycogen.
  • Type 1 Diabetes: An autoimmune condition where the pancreas produces little or no insulin. Treated with insulin injections.

Core knowledge

Key facts for Homeostasis & Response

1

Homeostasis

The maintenance of a constant internal environment in response to internal and external changes.

2

Negative Feedback

A control mechanism where a change in a condition triggers a response that reverses the change, returning to the optimum.

3

Thermoregulation

Maintaining body temperature at about 37°C. Controlled by the thermoregulatory centre in the brain (hypothalamus).

4

Vasoconstriction

Blood vessels near the skin surface narrow to reduce blood flow and heat loss when the body is too cold.

5

Vasodilation

Blood vessels near the skin surface widen to increase blood flow and heat loss when the body is too hot.

6

Blood Glucose Regulation

Controlled by the pancreas: insulin lowers blood glucose (stores as glycogen), glucagon raises it (breaks down glycogen).

7

Insulin

A hormone produced by the pancreas that causes cells to take up glucose from the blood and the liver to convert glucose to glycogen.

8

Type 1 Diabetes

An autoimmune condition where the pancreas produces little or no insulin. Treated with insulin injections.

Active recall

Close the notes and answer these

  1. 1.Without looking, explain homeostasis and give one example or consequence.
  2. 2.Without looking, explain negative feedback and give one example or consequence.
  3. 3.Without looking, explain thermoregulation and give one example or consequence.
  4. 4.Without looking, explain vasoconstriction and give one example or consequence.

Content reviewed 23 July 2026 against the current linked specification.

Finished learning?

Mark the notes complete, then test what you can recall.

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