Describe how physical digestion occurs in the mouth and explain how this process increases the effectiveness of chemical digestion.

Cambridge International IGCSE Biology (0610) — 7.3 Mechanical digestion · Describe and Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Incisors and canines bite and cut food into smaller pieces.
Molars and premolars chew and grind food into even smaller particles.
This physical digestion increases the surface area of the food.
A greater surface area allows digestive enzymes to act more quickly and efficiently during chemical digestion.

Examiner tips

Use the exact terms ‘incisors’, ‘canines’, ‘molars’, ‘premolars’ and ‘surface area’. Show the link between increased surface area and enzyme efficiency. Keep the answer concise – one sentence per point.
Use the word ‘chew’ for molars/premolars and ‘bite’ for incisors/canines to demonstrate understanding of different teeth functions.

Common mistakes

Confusing the roles of incisors/canines with molars/premolars. Failing to mention the increase in surface area. Using vague terms like ‘break down’ instead of ‘cut’ or ‘chew’.

Mark scheme (4 marks)

Incisors and/or canines bite and cut food into smaller pieces
Molars (and premolars) chew and grind food into smaller pieces
Physical digestion increases the surface area of food
A greater surface area allows enzymes to act more quickly / efficiently on the food during chemical digestion

Key terms in this question

physical digestion · chemical digestion