Skip to content
IGCSEBiology
Trial Class

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

Proteins and Amino Acids 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.

Test your understanding of how proteins are built from amino acids, and the diverse roles proteins play in living organisms.

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 2 Both 3 marks Difficulty 2/5

    State the elements present in all proteins and name the monomers that make up proteins.

    Show model answer and marking guidance
    1. Proteins contain carbon, hydrogen, oxygen, and nitrogen (some also contain sulfur).
    2. Proteins are made of amino acids.
    3. Amino acids are joined by peptide bonds.

  2. Question 2

    Paper 4 Both 4 marks Difficulty 3/5

    State four different functions of proteins in the body, giving a named example for each.

    Show model answer and marking guidance
    1. Enzymes: e.g. Amylase (catalyses starch digestion).
    2. Structural: e.g. Collagen (in skin, tendons).
    3. Transport: e.g. Haemoglobin (carries oxygen in red blood cells).
    4. Hormones: e.g. Insulin (controls blood glucose).

  3. Question 3

    Paper 4 Extended 3 marks Difficulty 4/5

    Explain why a change in amino acid sequence can affect how a protein functions.

    Show model answer and marking guidance
    1. Amino acid sequence determines the shape of the protein / its 3D structure.
    2. A change in sequence may change the shape / folding.
    3. If the active site shape changes, the substrate may no longer fit: the protein loses its function.

  4. Question 4

    Paper 4 Extended 3 marks Difficulty 3/5

    Describe the test for protein (Biuret test) and state the colour change observed.

    Show model answer and marking guidance
    1. Add Biuret reagent (sodium hydroxide solution then copper sulfate solution) to the sample.
    2. If protein is present, colour changes from blue to purple/violet.
    3. If no protein, the solution remains blue.

  5. Question 5

    Paper 2 Core 2 marks Difficulty 1/5

    State why proteins are needed in the diet of a growing child.

    Show model answer and marking guidance
    1. For growth: making new cells / tissues.
    2. For repair: replacing damaged cells.

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.

Review the related teaching