B3.2 + B3.3

Question 1

what is the digestive system?

Answer 1

Digestion is the breakdown of large insoluble molecules into small soluble molecules that are absorbed into the blood.

Question 2

what is the mouth’s role in the digestive system?

Answer 2

mechanical digestion (chewing)

enzymes (contained in saliva, the enzyme in the mouth is amylase and it turns starch -> glucose)

Question 3

what is the oesophagus’s role in the digestive system?

Answer 3

peristatic digestion

Question 4

what is stomach’s role in the digestive system?

Answer 4

hydrochloric acid (HCl) pH2

enzymes (protease turns protein -> amino acid)

Question 5

what is the role of the small intestine in the digestive system?

Answer 5

site of absorption (folds to increase the surface area which nutrience can be absorbed thin walls for short diffusion distance)

diffusion if there is more nutrience in the intestine, active transport if the is more nutrience in the blood

Question 6

what is the role of the pancreas in the digestive system?

Answer 6

contains the enzymes protease, amylase and lipase (lipids -> fatty acids + glycerol). Lipase is helped by bile (made in the liver and stored in the gall bladder, not an enzyme)

Question 7

what is the role of bile in the digestive system

Answer 7

made from the breakdown of old erythrocytes (red blood cells).
Produced in the liver and stored in the gallbladder. Uses are neutralization (it is an alkali) and emulsification (physically breaking down, not chemically). It is not an enzyme.

Question 8

Different parts of the human digestion system help to break down molecules of fat so that they can be absorbed into the body. Describe how. (6 marks)

To gain full marks you should refer to:

The enzyme and where it is produced

The products of digestion

Any other chemicals involved

Answer 8

In the small intestine, bile physically breaks down the lipids into droplets. This is so that they can have a larger surface area. The larger the surface area the faster the lipase can break it down. Lipase is the enzyme that breaks down lipids. Lipids are broken down into fatty acids and glycerol. The lipase that breaks down the lipids is produced in the pancreas. Bile is produced in the liver and stored in the gallbladder. The products are then absorbed by the small intestine.