Human Digestive System: MCQs and Questions
5 Multiple Choice Questions (MCQs)
1. The main site of absorption of digested food is:
b) Small intestine
2. The enzyme present in saliva is:
b) Amylase
3. Bile is poured into:
b) Small intestine
4. The correct sequence of the digestive system is:
a) Mouth → Oesophagus → Stomach → Small intestine → Large intestine → Anus
5. The function of villi is to:
b) Absorb digested food
5 Short Answer Questions (2 marks each)
1. Name the enzyme in gastric juice and its function.
Pepsin; it digests proteins into peptides.
2. What is the role of HCl in the stomach?
Makes the medium acidic for pepsin action and kills bacteria.
3. What is peristalsis?
Rhythmic contraction and relaxation of muscles in the alimentary canal to push food forward.
4. What is the function of bile juice?
Emulsifies fats, making them easier to digest by enzymes.
5. Name two enzymes from the pancreas.
Amylase and trypsin.
5 Medium Answer Questions (3 marks each)
1. Why is the small intestine the most important site for digestion and absorption?
- It is the longest part of the alimentary canal (about 6 m).
- It receives bile and pancreatic juice for digestion.
- It has villi that increase the surface area for absorption.
2. How are proteins digested in humans?
- In the stomach: Pepsin breaks proteins into peptides.
- In the small intestine: Trypsin from the pancreas further breaks peptides into amino acids.
- Amino acids are absorbed through villi into the blood.
3. Differentiate between ingestion and egestion.
- Ingestion: Taking food into the body (mouth).
- Egestion: Removal of undigested food (anus).
4. State three functions of the liver in digestion.
- Produces bile juice for fat emulsification.
- Stores excess glucose as glycogen.
- Detoxifies harmful substances from the blood.
5. Write a short note on villi.
- Finger-like projections found in the small intestine.
- They increase the surface area for absorption.
- They contain blood vessels and lacteals to absorb nutrients.
5 Long Answer Questions (4 marks each)
1. Describe the process of carbohydrate digestion starting from the mouth.
- Mouth: Salivary amylase breaks starch into maltose.
- Stomach: No further carbohydrate digestion occurs.
- Small intestine: Pancreatic amylase digests remaining starch; intestinal enzymes convert disaccharides to glucose.
- Glucose is absorbed into the blood through villi.
2. Explain the role of enzymes in digestion with examples.
Enzymes are biological catalysts that speed up digestion. Examples include:
- Amylase: Breaks down starch into sugar.
- Pepsin: Breaks down proteins into peptides.
- Lipase: Breaks down fats into fatty acids and glycerol.
- Trypsin: Breaks down peptides into amino acids.
3. Label the human digestive system and briefly describe its functions.
(Diagram to be drawn showing: Mouth, Oesophagus, Stomach, Liver, Pancreas, Small intestine, Large intestine, Anus.)
- Mouth: Chews and mixes food.
- Oesophagus: Moves food by peristalsis.
- Stomach: Protein digestion and acid secretion.
- Liver: Bile production.
- Pancreas: Enzyme secretion.
- Small intestine: Main site for digestion and absorption.
- Large intestine: Water absorption.
- Anus: Egestion of waste.
4. Explain fat digestion in humans.
- Fat digestion begins in the small intestine.
- Bile emulsifies fats, breaking large globules into smaller ones.
- Pancreatic lipase then digests fats into fatty acids and glycerol.
- These are absorbed into the lacteals within the villi.
5. Describe the adaptations of the small intestine for absorption.
- It is very long, providing more time and surface area for absorption.
- Villi and microvilli significantly increase the surface area.
- It has a rich blood supply for the rapid transport of absorbed nutrients.
- Its thin walls facilitate easy diffusion of nutrients.