Free Digestive system & digestion questions for IGCSE Biology (0610), part of Human nutrition. Each question has the answer and the marking points an examiner would look for.
Generate a full Digestive System & Digestion worksheet →All Human nutrition questionsBile is made in the liver and stored in the gall bladder.
1 Bile neutralises acidic mixture from the stomach.
2 Bile digests proteins into amino acids.
3 Bile emulsifies fats into small droplets.
Which statements are correct?
Answer: B
Bile is made in the liver and stored in the gall bladder.
Explain how bile helps the digestion of fats.
Explain one other function of bile.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | emulsifies, larger surface area for lipase bile emulsifies fats into small droplets B1 increases the surface area B1 for lipase to act on B1 | 3 |
| (b) | neutralises stomach acid neutralises acid from the stomach / provides alkaline conditions for enzymes B1 | 1 |
Teeth are involved in mechanical digestion.
Describe the functions of incisors and molars.
Explain how tooth decay is caused.
Explain why mechanical digestion speeds up chemical digestion.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | incisors cut/bite; molars grind incisors: cutting and biting B1 molars: grinding/chewing B1 | 2 |
| (b) | bacteria feed on sugar, produce acid, dissolves enamel bacteria in plaque feed on sugars B1 produce acid B1 acid dissolves the enamel B1 | 3 |
| (c) | larger surface area for enzymes it increases the surface area for enzymes to act on B1 | 1 |
This question is about the human digestive system.
Name the types of human teeth and state the function of each.
Explain how chewing food helps chemical digestion.
Explain how tooth decay is caused.
Name the enzyme that digests starch, where it is secreted, and the final product of starch digestion in the small intestine.
Explain why proteins must be digested before they can be used by the body.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | incisors cut; canines tear; premolars and molars grind incisors – cutting / biting B1 canines – tearing / holding B1 premolars – grinding / chewing B1 molars – grinding / crushing B1 | 4 |
| (b) | breaks into smaller pieces; larger surface area for enzymes breaks food into smaller pieces B1 increasing the surface area for enzymes to act on B1 | 2 |
| (c) | bacteria feed on sugars; produce acid; acid dissolves enamel bacteria in plaque feed on sugars B1 and produce acid B1 the acid dissolves / damages the enamel and dentine B1 | 3 |
| (d) | amylase; salivary glands and pancreas; glucose (maltase on maltose) amylase B1 secreted by the salivary glands and pancreas B1 maltose is broken down to glucose by maltase on the small intestine lining B1 | 3 |
| (e) | large insoluble molecules; must be broken into amino acids to be absorbed proteins are large, insoluble molecules that cannot be absorbed B1 they must be broken down into small soluble amino acids B1 | 2 |
Hydrochloric acid is secreted in the stomach.
State two functions of the acid.
Name the products of protein digestion.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | kills bacteria; optimum pH for pepsin kills harmful microorganisms in food B1 provides acid pH for pepsin/protease B1 | 2 |
| (b) | amino acids amino acids B1 | 1 |
This question is about digestion in humans.
Distinguish between mechanical digestion and chemical digestion.
Name the enzyme that digests protein in the stomach, and the products of protein digestion.
Explain why the stomach contains hydrochloric acid.
Describe the role of bile in the digestion of fats.
Describe how villi are adapted for the absorption of digested food.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | mechanical: breaking food into smaller pieces without changing molecules; chemical: enzymes break large molecules into small soluble ones mechanical: physical breakdown into smaller pieces without chemical change B1 chemical: large insoluble molecules broken into small soluble molecules (by enzymes) B1 | 2 |
| (b) | pepsin; amino acids pepsin (protease) B1 amino acids B1 | 2 |
| (c) | kills bacteria; optimum pH for pepsin kills bacteria in food B1 provides an acid pH, the optimum for pepsin B1 | 2 |
| (d) | emulsifies fats into droplets; larger surface area for lipase; neutralises acid bile emulsifies fats into small droplets B1 increasing the surface area for lipase to act on B1 bile is alkaline and neutralises stomach acid so enzymes in the small intestine work at optimum pH B1 | 3 |
| (e) | large surface area; microvilli; thin wall (one cell thick); capillaries; lacteal Any 4 of: villi give a large surface area; microvilli increase the surface area further; wall one cell thick for short diffusion distance; good blood supply (capillary network) maintains a concentration gradient; lacteal absorbs fatty acids and glycerol B4 | 4 |
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