The Digestive System

Question 1

Define digestion.

Answer 1

The process of breaking down large, insoluble food molecules into smaller, soluble molecules that can be absorbed into the bloodstream.

Question 2

What is peristalsis?

Answer 2

The wave-like contractions of circular and longitudinal muscles that push food along the alimentary canal.

Question 3

Define absorption.

Answer 3

The movement of small, soluble molecules (e.g., glucose, amino acids) from the digestive tract into the blood or lymph.

Question 4

What is an enzyme?

Answer 4

A biological catalyst that speeds up the rate of a chemical reaction without being used up.

Question 5

What is the function of bile in digestion?

Answer 5

Bile emulsifies fats, increasing the surface area for the action of lipase.

Question 6

Define emulsification.

Answer 6

The process of breaking down large fat droplets into smaller droplets, increasing surface area for enzyme action.

Question 7

What is the role of the epithelial cells in the small intestine?

Answer 7

They contain enzymes and transport proteins for the absorption of nutrients.

Question 8

What is the function of the villi in the small intestine?

Answer 8

To increase surface area for absorption of nutrients.

Question 9

Define assimilation.

Answer 9

The process of using absorbed nutrients to build new molecules or structures in cells.

Question 10

What is the role of hydrochloric acid in the stomach?

Answer 10

Provides an acidic environment for pepsin activation and kills pathogens.

Question 11

Define egestion.

Answer 11

The removal of undigested waste material and faeces from the body.

Question 12

What is the role of the pancreas in digestion?

Answer 12

Secretes digestive enzymes (amylase, lipase, trypsin) and bicarbonate into the small intestine.

Question 13

What is the role of lipase in digestion?

Answer 13

Breaks down lipids into fatty acids and glycerol.

Question 14

Define maltase and state its substrate and product.

Answer 14

An enzyme that breaks down maltose into glucose in the small intestine.

Question 15

What is the role of the large intestine in digestion?

Answer 15

Absorbs water and minerals; forms and compacts faeces.

Question 16

What is the function of the lacteals in the villi of the small intestine?

Answer 16

Absorb fatty acids and glycerol into the lymphatic system.

Question 17

Define pepsin and state where it acts.

Answer 17

A protease enzyme that breaks down proteins into peptides in the stomach.

Question 18

What is the function of secretin in digestion?

Answer 18

Stimulates the release of bicarbonate from the pancreas to neutralise stomach acid.

Question 19

What is the emulsion test for lipids?

Answer 19

Mix sample with ethanol, then add water. A milky-white emulsion indicates the presence of lipids.

Question 20

Define trypsin and state its substrate and product.

Answer 20

A protease enzyme produced in the pancreas; breaks proteins into peptides in the small intestine.

Question 40

What are the main functions of the digestive system?

Answer 40

Ingestion, digestion, absorption, assimilation, and egestion.

Question 41

Name the enzyme that breaks down starch in the mouth and state the product formed.

Answer 41

Amylase – breaks down starch into maltose.

Question 42

Describe how peristalsis moves food through the digestive system.

Answer 42

Circular and longitudinal muscles contract and relax in a wave-like motion to push food along the alimentary canal.

Question 43

What is the role of hydrochloric acid (HCl) in the stomach?

Answer 43

Creates acidic pH (~2) to kill pathogens and activate pepsin for protein digestion.

Question 44

Which enzyme is secreted in an inactive form in the stomach, and how is it activated?

Answer 44

Pepsin is secreted as pepsinogen and activated by HCl.

Question 45

Name the enzyme that digests proteins in the small intestine and the product formed.

Answer 45

Trypsin – breaks down proteins into peptides.

Question 46

What is the function of bile and where is it produced and stored?

Answer 46

Bile emulsifies fats (increases surface area); produced in the liver, stored in the gallbladder.

Question 47

How are lipids digested in the small intestine?

Answer 47

Lipase (from pancreas) breaks triglycerides into fatty acids and glycerol.

Question 48

What structural feature of the small intestine increases surface area for absorption?

Answer 48

Villi and microvilli.

Question 49

How are glucose and amino acids absorbed into the bloodstream?

Answer 49

Through active transport and facilitated diffusion into capillaries.

Question 50

What is the function of lacteals in the villi of the small intestine?

Answer 50

Absorb fatty acids and glycerol into the lymphatic system.

Question 51

Explain the role of the pancreas in digestion.

Answer 51

Secretes pancreatic juice containing amylase, trypsin, and lipase into the small intestine.

Question 52

How does the body maintain a suitable pH in the small intestine?

Answer 52

Bicarbonate from the pancreas neutralises stomach acid.

Question 53

What is the main function of the large intestine (colon)?

Answer 53

Absorbs water and minerals, forming faeces.

Question 54

How are faeces expelled from the body?

Answer 54

Through the rectum and anus by the contraction of sphincter muscles.

Question 55

Name the hormone that stimulates the release of gastric juice in the stomach.

Answer 55

Gastrin.

Question 56

What is the function of cholecystokinin (CCK) in digestion?

Answer 56

Stimulates the release of bile from the gallbladder and enzymes from the pancreas.

Question 57

What is the difference between mechanical and chemical digestion?

Answer 57

Mechanical digestion = physical breakdown of food; Chemical digestion = enzyme action breaking down molecules.

Question 58

What is the role of mucus in the digestive system?

Answer 58

Protects the stomach lining from acid and lubricates food for swallowing.

Question 59

What test is used to identify the presence of lipids in a sample?

Answer 59

Emulsion test – Mix with ethanol, then add water → Positive result = white emulsion.