§-Topic

Topic 3: Homeostasis

7 dot points, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.

How do the kidneys regulate water balance and remove waste?

Explain how the kidney and ADH regulate water balance through filtration, reabsorption and negative feedback

The kidney regulates water balance by filtering blood and reabsorbing water and solutes in the nephron; ADH adjusts water reabsorption by negative feedback to control urine concentration.

9 min read →

How do hormones coordinate slower, longer-lasting responses?

Describe how the endocrine system uses hormones to coordinate responses and compare it with the nervous system

The endocrine system releases hormones into the blood to act on target cells with matching receptors, giving slower but longer-lasting coordination than the nervous system.

8 min read →

How does the body keep its internal environment stable?

Explain the principle of homeostasis and how negative feedback maintains a stable internal environment

Homeostasis keeps internal conditions within a narrow range using negative feedback loops of receptor, control centre and effector that reverse changes from a set point.

8 min read →

How do plants control water loss while still exchanging gases?

Explain transpiration and how plants regulate water loss through stomata and guard cells

Transpiration is water loss through stomata; guard cells open and close stomata to balance gas exchange against water loss, with the rate affected by environmental factors.

8 min read →

How does the body keep blood glucose within a safe range?

Explain how insulin and glucagon regulate blood glucose by negative feedback, and how diabetes disrupts this

The pancreas regulates blood glucose by negative feedback: insulin lowers high glucose and glucagon raises low glucose; diabetes results from faulty insulin production or response.

8 min read →

How does the nervous system carry rapid signals around the body?

Describe the structure of neurons and explain how nerve impulses and synaptic transmission carry information

Neurons carry electrical impulses (action potentials) along axons and pass signals across synapses using neurotransmitters, providing fast coordination in homeostasis.

9 min read →

How does the body keep its core temperature stable?

Explain how the body regulates core temperature through negative feedback and the responses to heat and cold

The hypothalamus regulates core temperature by negative feedback; cooling responses (sweating, vasodilation) and warming responses (shivering, vasoconstriction) reverse changes.

8 min read →