Homeostasis & Response is a core part of GCSE Biology. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
HomeostasisKeeping internal conditions stable despite outside changes
ReceptorCell that detects a stimulus like light or heat
EffectorMuscle or gland that carries out the response
NeuroneNerve cell that sends fast electrical signals
SynapseTiny gap between neurones bridged by chemicals
Reflex arcFast automatic pathway that skips the brain
Reaction timeTime between a stimulus and your response
Sensory neuroneCarries signals from receptors to the CNS
Relay neuroneConnects sensory and motor neurones in the CNS
Motor neuroneCarries signals from the CNS to an effector
NeurotransmitterChemical that carries a signal across a synapse
Ruler drop testMeasures reaction time using how far a ruler falls
AccommodationHow the eye changes lens shape to focus near or far
Ciliary muscleRing of muscle that changes lens shape
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
What does negative feedback do in homeostasis?✗ Negative feedback makes a process get worse or amplifies the change. ✓ It reverses a change in a controlled variable, bringing it back towards the set point.
Why is a reflex action faster than a conscious response?✗ The brain decides reflexes faster than other actions because it skips thinking. ✓ The signal does not need to be processed by the brain — it travels through a simpler reflex arc via the spinal cord.
Does negative feedback make a change worse?✗ Negative feedback amplifies the original change. ✓ No — negative feedback opposes and reverses a change, returning the condition to its set point.
How are signals transmitted across a synapse between two neurones?✗ The electrical signal jumps directly from one neurone to the next across the synaptic gap. ✓ Via neurotransmitter chemicals released from the presynaptic neurone, which bind receptors on the postsynaptic neurone.
In the ruler drop test, what does a SHORTER catch distance mean?✗ Slower reaction time ✓ Faster reaction time
Practise Homeostasis & Response — free games
Test yourself with these quick revision games for this topic:
See all 17 games in the Subjects Arcade →
More GCSE Biology topics
← All revision guides
Want to revise every topic this smart?
The Velvet Method teaches you to use AI to revise any subject — £25, lifetime access.
Explore the Course →