Describe the role of physical digestion in the mouth, including the functions of different types of teeth and how physical digestion assists chemical digestion.

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

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

Model answer (4 marks)

Physical digestion in the mouth breaks food into smaller pieces without chemical change.
1. Incisors (and canines) cut or bite food into manageable pieces.
2. Molars (and premolars) chew and grind the food, further reducing particle size.
3. By increasing the surface area of food, physical digestion allows enzymes in saliva to act more efficiently, speeding up chemical digestion.

Examiner tips

  • Use the word "breaks" and "increases surface area" – these are key phrases in the mark scheme.
  • Mention all tooth types (incisors, canines, molars, premolars) and their specific actions.
  • Show the link between smaller particles and enzyme action to earn the final mark.

Common mistakes

  • Omitting the role of canines or premolars.
  • Failing to state that physical digestion does not involve chemical change.
  • Not linking increased surface area to enzyme efficiency.

Mark scheme (4 marks)

  1. Physical digestion breaks food into smaller pieces (without chemical change)
  2. Incisors (and/or canines) cut or bite food
  3. Molars (and/or premolars) chew and grind food
  4. Physical digestion increases the surface area of food for enzyme action in chemical digestion

Key terms in this question

physical digestion · chemical digestion

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