Describe the role of bile in the digestion and absorption of fats.

Eduqas GCSE Biology — 1.3.2 Digestion and absorption · 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.
It emulsifies dietary fats, breaking them into small droplets.
This increases the surface area available for pancreatic lipase to act on.
Bile also neutralises stomach acid, making the small intestine alkaline and providing the optimum pH for lipase activity.

Examiner tips

Use the exact terms ‘emulsifies’, ‘surface area’, ‘neutralises’, ‘alkaline’, ‘optimum pH’
Show the sequence: production → storage → action on fats → pH adjustment
Mention both the mechanical (emulsification) and chemical (pH) roles

Common mistakes

Confusing bile with pancreatic juice or mistaking bile for digestive enzymes
Omitting the role of bile in neutralising acid or the increase in surface area
Using vague language such as ‘helps digestion’ without specifics

Mark scheme (4 marks)

Bile is produced by the liver (and stored in the gall bladder)
Bile emulsifies fats / breaks fats into smaller droplets
This increases the surface area of fat (for enzymes to act on)
Bile neutralises stomach acid / makes conditions in the small intestine alkaline / provides the optimum pH for lipase

Key terms in this question

bile