Question Constellation Sign up for free AQA · GCSE · Biology · Higher
CF Digestion and Body Mass
The pancreas produces several digestive enzymes. CF reduces the amount of each enzyme that reaches the small intestine.
Explain why a person with CF has:
- difficulty digesting food
- difficulty gaining body mass
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Marking points
- 1 Explains how reduced delivery of named digestive enzymes reduces breakdown of their food substrates.
- 2 Explains that fewer small soluble digestion products are available for absorption.
- 3 Logically links reduced absorption to reduced storage, growth or energy release and therefore difficulty gaining body mass.
Full-mark answer
Because less pancreatic enzyme reaches the small intestine, less fat is digested by lipase into fatty acids and glycerol, less starch is digested by amylase into sugars, and less protein is digested by protease into amino acids. Fewer small soluble products are therefore absorbed into the blood. This leaves fewer molecules for making new cells, tissues and muscle, less fat to store, and less glucose for respiration, so less energy is released for growth and the person has difficulty gaining mass.
Why this answer loses marks
The person cannot digest food properly, so they do not gain mass.
This skips the enzyme, soluble-product and absorption links needed to connect CF to reduced body-mass gain.