This exam focus covers Exam Focus within Water Regulation for GCSE Biology. Topic 7: Water Regulation It is section 9 of 11 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 9 of 11
Practice
15 questions
Recall
20 flashcards
Exam Focus
Very Frequently Examined — AQA Paper 2Water regulation is tested in almost every AQA Paper 2 sitting. The most common question types are:
- 6-mark extended response: "Explain how ADH controls water levels in the blood" — cover the stimulus (dehydration), osmoreceptors, pituitary release, effect on collecting duct, reabsorption, and negative feedback for full marks.
- Graph interpretation: ADH concentration vs urine volume graphs — as ADH rises, urine volume falls. Describe the relationship using data from the graph.
- Compare dialysis and transplant (4 marks): Always give balanced points — advantage and disadvantage of each, not just lists about one treatment.
- Urine concentration questions: State whether a given scenario (exercise, drinking alcohol, diabetes insipidus) produces concentrated or dilute urine and explain why using ADH.
Key phrase to use: "ADH increases the permeability of the collecting duct, so more water is reabsorbed into the blood by osmosis."