Digestive System
Level 2 (Recall & Understanding)
Time: 30 minutes Total Marks: 40
Answer all questions. Marks are shown in brackets.
Q1. State two main functions of the digestive system. [2]
Q2. Trace the path of food through the alimentary canal by naming the organs in the correct order, starting from the mouth and ending at the anus. [6]
Q3. Copy and complete the table to distinguish mechanical and chemical digestion. [4]
| Feature | Mechanical Digestion | Chemical Digestion |
|---|---|---|
| Definition | (i) | (ii) |
| Example | (iii) | (iv) |
Q4. Describe the role of teeth and saliva in the mouth. In your answer, name one enzyme found in saliva and state its substrate. [4]
Q5. Explain the function of the stomach. In your answer: (a) Name the acid present in gastric juice and state one of its functions. [2] (b) Name the protein-digesting enzyme in the stomach and its substrate. [2]
Q6. The small intestine is adapted for absorption. (a) Name the finger-like projections lining the small intestine. [1] (b) Name the even smaller projections found on the surface of these structures. [1] (c) Explain how these structures increase the efficiency of absorption. [2]
Q7. State the role of the pancreas and of bile in digestion. [4]
Q8. Match each enzyme to its correct substrate. [4]
| Enzyme | Substrate |
|---|---|
| (a) Amylase | 1. Proteins |
| (b) Lipase | 2. Starch |
| (c) Protease | 3. Maltose |
| (d) Maltase | 4. Fats (lipids) |
Q9. Explain the main function of the large intestine. [3]
Q10. Define peristalsis and state where in the digestive system it occurs. [3]
End of Paper
Answer keyMark scheme & solutions
Q1. [2] Any two (1 mark each):
- Ingestion / intake of food.
- Digestion — breaking food into small, soluble molecules.
- Absorption of nutrients into the blood.
- Egestion / removal of undigested waste.
Why: These are the core stages the system performs.
Q2. [6] Correct order (1 mark each, in sequence): Mouth → Oesophagus → Stomach → Small intestine → Large intestine → Rectum → Anus. (Award full 6 if mouth, oesophagus, stomach, small intestine, large intestine, anus all correct in order.)
Why: Food moves down the continuous alimentary canal in one direction.
Q3. [4] (1 mark each)
- (i) Physical breakdown of food into smaller pieces without changing its chemical nature.
- (ii) Breakdown of large molecules into smaller molecules using enzymes (chemical change).
- (iii) Chewing by teeth / churning in stomach.
- (iv) Starch → maltose by amylase (or protein → amino acids, etc.).
Why: Mechanical = size change only; chemical = molecular change via enzymes.
Q4. [4]
- Teeth mechanically break food into smaller pieces, increasing surface area for enzymes (1).
- Saliva moistens/lubricates food for swallowing (1).
- Enzyme: salivary amylase (1).
- Substrate: starch (broken into maltose) (1).
Q5. [4] (a) Acid: hydrochloric acid (HCl) (1). Function: kills bacteria / provides acidic pH for enzyme action / activates pepsin (any one, 1). (b) Enzyme: pepsin (protease) (1). Substrate: proteins (1).
Q6. [4] (a) Villi (1). (b) Microvilli (1). (c) They greatly increase surface area for absorption (1); thin walls / rich blood supply allow faster diffusion of nutrients into blood (1).
Q7. [4]
- Pancreas: secretes pancreatic juice containing digestive enzymes (amylase, lipase, protease) into the small intestine (1) to digest carbohydrates, fats, proteins (1).
- Bile: made by liver, stored in gall bladder; emulsifies fats into small droplets (1), increasing surface area for lipase / and neutralises stomach acid (1).
Q8. [4] (1 mark each)
- (a) Amylase → 2 (Starch)
- (b) Lipase → 4 (Fats)
- (c) Protease → 1 (Proteins)
- (d) Maltase → 3 (Maltose)
Q9. [3]
- Reabsorbs water from undigested material (1).
- Absorbs some mineral salts / vitamins (1).
- Forms and stores faeces for egestion (1).
Q10. [3]
- Peristalsis is the wave-like contraction and relaxation of muscles in the gut wall (1) that pushes food along the alimentary canal (1).
- Occurs throughout the canal, e.g. oesophagus / intestines (1).
[
{"claim":"Alimentary canal path has 7 named stages from mouth to anus", "code":"path=['mouth','oesophagus','stomach','small intestine','large intestine','rectum','anus']; result=(len(path)==7 and path[0]=='mouth' and path[-1]=='anus')"},
{"claim":"Enzyme-substrate matching pairs are all distinct and total four", "code":"pairs={'amylase':'starch','lipase':'fats','protease':'proteins','maltase':'maltose'}; result=(len(pairs)==4 and len(set(pairs.values()))==4)"},
{"claim":"Total marks sum to 40", "code":"marks=[2,6,4,4,4,4,4,4,3,3]; result=(sum(marks)==38+2 and sum(marks)==40)"}
]