Explain how peristalsis moves food along the oesophagus.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
The oesophagus is a muscular tube.
1. Circular muscle fibres behind the bolus contract.
2. Circular muscle fibres in front of the bolus relax.
3. The contraction behind and relaxation ahead create a wave.
4. This wave of contraction pushes the food toward the stomach.
1. Circular muscle fibres behind the bolus contract.
2. Circular muscle fibres in front of the bolus relax.
3. The contraction behind and relaxation ahead create a wave.
4. This wave of contraction pushes the food toward the stomach.
Examiner tips
- Use the term "oesophagus" and "muscular tube". Show the sequence of contraction behind and relaxation ahead. Explain that the wave moves the food. Keep each point short and to the point.
Common mistakes
- Forgetting to mention the oesophagus is muscular. Describing only contraction without the relaxation. Using vague terms like "pushes" without linking to peristaltic wave.
Mark scheme (4 marks)
- The oesophagus has muscular walls / is a muscular tube
- Circular muscles contract behind the bolus / food
- Circular muscles relax in front of the bolus / food
- This creates a wave of muscular contraction that pushes the food towards the stomach
Key terms in this question
Related
- All Cambridge International IGCSE Biology (0610) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →