Explain why a diet lacking in iron can cause a person to feel tired.

Cambridge International IGCSE Biology (0610) — 7.1 Diet · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Iron is required for the synthesis of haemoglobin.
Without enough iron, haemoglobin production falls, causing anaemia.
Haemoglobin carries oxygen; reduced haemoglobin means less oxygen reaches tissues.
Lower oxygen availability limits aerobic respiration, decreasing ATP production and leading to tiredness.

Examiner tips

Use the exact terms: haemoglobin, anaemia, aerobic respiration. Show the causal chain from iron to tiredness. Keep each point short and to the point. Use a logical order: iron → haemoglobin → oxygen transport → energy production → tiredness.

Common mistakes

Confusing iron deficiency with other causes of fatigue. Using vague words like "low energy" instead of "less ATP". Omitting the link between haemoglobin and oxygen transport.

Mark scheme (4 marks)

Iron is needed for the production of haemoglobin.
Without sufficient iron, less haemoglobin is produced, leading to anaemia.
Haemoglobin transports / carries oxygen in the blood, so less haemoglobin means less oxygen is delivered to cells.
Less oxygen reaching cells means less aerobic respiration occurs, so less energy is released, causing tiredness.

Key terms in this question

iron