Describe the role of bile in the digestion of fats in the small intestine.

Cambridge International IGCSE Biology (0610) — 7.2 Alimentary canal · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Bile is produced by the liver and stored in the gall bladder before being secreted into the duodenum.
Bile emulsifies fats, breaking them into smaller droplets.
Emulsification increases the surface area of fats available for lipase to act upon.
Bile is alkaline and neutralises the acidic stomach contents entering the duodenum, providing a suitable pH for lipase to work.

Examiner tips

Use the exact terms ‘bile’, ‘emulsifies’, ‘surface area’, ‘alkaline’, ‘neutralises’, ‘duodenum’, ‘lipase’.
Show the sequence: production → storage → secretion → action on fats → pH adjustment.
Keep each point concise and separate with line breaks or numbering.

Common mistakes

Confusing bile with pancreatic juice or omitting the alkaline property.
Using vague phrases like ‘helps digestion’ instead of specific actions such as ‘emulsifies’ and ‘neutralises’.

Mark scheme (4 marks)

Bile is produced by the liver and stored in the gall bladder before being secreted into the duodenum.
Bile emulsifies fats, breaking them into smaller droplets.
Emulsification increases the surface area of fats available for lipase to act upon.
Bile is alkaline and neutralises the acidic stomach contents entering the duodenum, providing a suitable pH for lipase to work.

Key terms in this question

bile