Describe the role of red blood cells in transporting oxygen around the body.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Red blood cells contain haemoglobin, which binds oxygen in the lungs to form oxyhaemoglobin. The oxyhaemoglobin then travels through the bloodstream to tissues, where it releases oxygen and returns to haemoglobin. Red blood cells lack a nucleus, providing extra space for haemoglobin, and their biconcave shape gives a large surface area for oxygen absorption.
Examiner tips
- Use the term haemoglobin and oxyhaemoglobin; mention binding in lungs and release in tissues.
- Explain the structural advantage of no nucleus and biconcave shape.
- Keep the answer concise and to the point.
- Use UK spelling (haemoglobin, haemoglobin).
Common mistakes
- Forgetting to mention the release of oxygen in tissues.
- Using the wrong spelling (hemoglobin).
- Including unnecessary details such as blood pressure or heart function.
Mark scheme (4 marks)
- Red blood cells contain haemoglobin
- Haemoglobin combines with oxygen (in the lungs) to form oxyhaemoglobin
- Oxyhaemoglobin releases / splits back into oxygen and haemoglobin at the tissues / body cells
- Red blood cells have no nucleus, allowing more space to carry haemoglobin / oxygen OR have a biconcave shape giving a large surface area for oxygen absorption
Key terms in this question
Related
- All Eduqas GCSE Biology revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →