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IGCSEBiology
Trial Class

Original practice · 5 questions · 14 marks · about 16 minutes

Liver Functions and Excretion 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 test your understanding of the liver's role in excretion, particularly the breakdown of excess amino acids.

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 3 marks Difficulty 3/5

    Define excretion and explain why it is different from egestion.

    Show model answer and marking guidance
    1. Excretion: removal of waste products of metabolism from the body.
    2. Egestion: removal of undigested food from the body (as faeces through the anus).
    3. Faeces were never part of the body's metabolism: they passed through the gut without being absorbed.

    Watch for: Confusing excretion and egestion is one of the most common IGCSE errors.

  2. Question 2

    Paper 4 Extended 3 marks Difficulty 4/5

    Describe the process of deamination and explain why it is necessary.

    Show model answer and marking guidance
    1. Deamination is the removal of the amino (nitrogen-containing) group from excess amino acids.
    2. This occurs in the liver.
    3. The amino group is converted to urea (which is excreted by the kidneys); the remainder is converted to glycogen or used for energy.

  3. Question 3

    Paper 4 Both 3 marks Difficulty 3/5

    State three functions of the liver.

    Show model answer and marking guidance
    1. Deamination of excess amino acids: producing urea.
    2. Production of bile: stored in the gall bladder.
    3. Detoxification: breaking down toxic substances such as alcohol.

  4. Question 4

    Paper 2 Core 2 marks Difficulty 2/5

    Name the waste product formed from the breakdown of excess amino acids in the liver.

    Show model answer and marking guidance
    1. Urea.
    2. Urea is transported in the blood to the kidneys for excretion.

  5. Question 5

    Paper 4 Extended 3 marks Difficulty 4/5

    Explain why amino acids cannot be stored in the body, unlike glucose and fats.

    Show model answer and marking guidance
    1. Excess amino acids contain nitrogen in the amino group.
    2. The nitrogen-containing part cannot be stored: it would be toxic.
    3. So excess amino acids must be deaminated in the liver: the amino group is removed and converted to urea.

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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