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IGCSEBiology
Trial Class

Original practice · 5 questions · 15 marks · about 17 minutes

Water Balance and ADH Practice Questions

Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.

These questions focus on how the body maintains water balance through the action of ADH on the kidneys.

Before you open the answers

  • Attempt every question without notes.
  • Show working for calculations and write complete biological statements.
  • Use the suggested time as a guide, not a strict limit on the first attempt.

These are original practice questions. They do not reproduce an official Cambridge paper or official mark scheme.

  1. Question 1

    Paper 4 Extended 4 marks Difficulty 4/5

    Describe how ADH controls the water content of the blood when a person is dehydrated.

    Show model answer and marking guidance
    1. Blood water level falls / blood becomes more concentrated.
    2. The pituitary gland releases more ADH into the blood.
    3. ADH makes the walls of the collecting duct more permeable to water.
    4. More water is reabsorbed from the collecting duct back into the blood: urine becomes more concentrated / smaller volume.

  2. Question 2

    Paper 4 Extended 3 marks Difficulty 3/5

    Predict the effect on urine volume and concentration when a person drinks a large amount of water. Explain your answer.

    Show model answer and marking guidance
    1. Urine volume increases (more dilute urine).
    2. Blood becomes more dilute: less ADH is released.
    3. Collecting duct walls become less permeable: less water is reabsorbed, more is excreted.

  3. Question 3

    Paper 4 Extended 3 marks Difficulty 3/5

    Name the hormone involved in water balance, where it is produced, and where it acts.

    Show model answer and marking guidance
    1. ADH (antidiuretic hormone).
    2. Produced by the pituitary gland (in the brain).
    3. Acts on the collecting ducts of the kidneys.

  4. Question 4

    Paper 2 Core 2 marks Difficulty 2/5

    State what happens to urine colour when a person does not drink enough water.

    Show model answer and marking guidance
    1. Urine becomes darker in colour (more concentrated).
    2. More water is reabsorbed by the kidneys: less water in the urine.

  5. Question 5

    Paper 4 Extended 3 marks Difficulty 4/5

    Explain the role of negative feedback in the control of blood water level.

    Show model answer and marking guidance
    1. A change in blood water level is detected (e.g. Blood too concentrated).
    2. ADH is released, causing more water to be reabsorbed: blood water level rises.
    3. As blood water level returns to normal, ADH release is reduced: this prevents over-correction.

Mark the set consistently

Award a point only when the idea is clearly present in the written answer. Correct any missed point in a complete sentence, then test the same skill on a different question several days later.

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