A sports nutrition company claims that athletes need to increase their intake of protein, carbohydrates and iron compared to non-athletes. Explain why each of these three nutrients is particularly important for an athlete's body.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Athletes train intensively and their bodies undergo significant physiological demands, including muscle repair, sustained energy release and efficient oxygen transport during exercise.
Model answer (5 marks)
1. Protein is required for the growth and repair of muscle cells and tissues that are damaged during intense training.
2. Carbohydrates are the main source of energy; they provide glucose for muscle contraction and sustain exercise performance.
3. Iron is essential for the synthesis of haemoglobin in red blood cells.
4. Haemoglobin carries oxygen to the working muscles, so a higher iron intake improves oxygen delivery during exercise.
5. Athletes therefore need more protein, carbohydrates and iron because their muscles work harder, are damaged and repaired more frequently, and consume energy at a greater rate.
2. Carbohydrates are the main source of energy; they provide glucose for muscle contraction and sustain exercise performance.
3. Iron is essential for the synthesis of haemoglobin in red blood cells.
4. Haemoglobin carries oxygen to the working muscles, so a higher iron intake improves oxygen delivery during exercise.
5. Athletes therefore need more protein, carbohydrates and iron because their muscles work harder, are damaged and repaired more frequently, and consume energy at a greater rate.
Examiner tips
- Use the exact phrases from the mark scheme (e.g. "growth and repair of muscle cells", "main source of energy", "haemoglobin in red blood cells"),
- Show the logical link between each nutrient and the athlete’s physiological demand,
- Keep each point brief but complete – one sentence per point is enough for 5 marks.
Common mistakes
- Confusing protein with carbohydrate as the main energy source; students often say protein is the main energy source.
- Failing to mention haemoglobin or oxygen transport when discussing iron.
- Writing vague statements such as "athletes need more nutrients" without specifying why each is important.
Mark scheme (5 marks)
- Protein is needed for growth and repair of muscle cells / tissues
- Carbohydrates are the main source of energy / provide energy for muscle contraction and exercise
- Iron is needed to make haemoglobin in red blood cells
- Haemoglobin / red blood cells carry oxygen to the muscles, so more iron means more efficient oxygen delivery during exercise
- An athlete has a higher demand for all three nutrients because their muscles are working harder / being damaged and repaired more frequently / energy is used at a greater rate
Key terms in this question
protein · carbohydrates · iron
Related
- All OCR A-Level Biology B — Advancing Biology (H422) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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