Homeostasis: GCSE Combined Science
Keeping conditions constant: nerves, reflexes, hormones, blood glucose, water and nitrogen balance
The short version
Define homeostasis, describe the reflex arc, endocrine glands, insulin and glucagon, and water/urea balance.
Key idea
Negative feedback reverses the change
Grade 2–3: Homeostasis keeps your temperature and sugar from going silly.
Grade 5–6: I can write receptor, coordinator, effector.
Grade 9: I say negative feedback and I can contrast nervous (fast, short, electrical) with hormonal (slower, longer, blood-borne).
Go a bit deeper
Impulse along axon. At the synapse, transmitter diffuses across the gap and starts an impulse in the next neurone. One-way because transmitter is only in vesicles on one side.
Grade 2–3: Messages travel along nerves to the brain and out to muscles.
Grade 5–6: I can label cell body, axon, myelin, synapse.
Worked example
Worked example
Grade 2–3: Homeostasis keeps your temperature and sugar from going silly. Grade 5–6: I can write receptor, coordinator, effector. Grade 9: I say negative feedback and I can contrast nervous (fast, short, electrical) with hormonal (slower, longer, blood-borne).
Lessons in this topic
- Homeostasis principles
- The nervous system
- Reflexes
- The endocrine system
- Control of blood glucose
- Water and nitrogen balance
In the app each lesson is video (when we have a real YouTube id) then intro, learn and summary steps.
What the examiner wants
Sequence the reflex arc with synapses, explain negative feedback for glucose and ADH, and compare Type 1 and Type 2 diabetes treatments.
Try these questions
Cover the answers and have a go first. Worked solutions are underneath.
Homeostasis is...
Which is a correct comparison of nervous and hormonal control?
The CNS is made of...
The correct order for a coordinated response is...
Common mistakes
- Homeostasis is not “keeping still”. It is constant conditions, often by lots of tiny adjustments.
- The brain is not a hormone. Coordination can be spinal (reflex) without thinking.
- Insulin is not produced in the liver. It is made in the pancreas and acts on liver (and muscle) to take up glucose.
- Insulin does not “break down sugar in the stomach”. It acts after glucose is in the blood.
Answers and working
Frequently asked questions
Is GCSE Homeostasis on Combined Science and Triple?
Homeostasis is on Combined Science and on Triple Biology. Progress is shared in the ReviseEasy app.
Which exam board is this Homeostasis page for?
The ideas are board-agnostic for AQA, Edexcel, OCR, WJEC and CCEA. Paper lengths and question numbers differ — check your specification.
Is Homeostasis Foundation or Higher?
The core ideas appear on both tiers. Higher papers add extra application and some HT-only detail, marked in lessons with a Higher badge.
Learn, try, get feedback, fix the mistake
Open the stepped lesson, then the quiz with hints. Required-practical and calculation questions use the same method you will need in the paper.
Learn Homeostasis on ReviseEasy →Related revision
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