B3.6 How the digestive system works

Question 1

Three types f enzymes found in the body are called amylase, protease and lipase .
a Explain where each enzyme is made in the body

Answer 1

amylase: salivary glands, pancreas
protease: stomach, pancreas, small intestine
lipase: pancreas, small intestine

Question 2

Three types f enzymes found in the body are called amylase, protease and lipase .
Explain which reaction each enzyme catalyses .

Answer 2

amylase: carbohydrate to sugar
protease: proteins to amino acids
lipase: lipids to fatty acids and glycerol

Question 3

Three types f enzymes found in the body are called amylase, protease and lipase .
Explain where each reaction works in the digestive system

Answer 3

amylase: mouth, small intestine
protease: stomach, small intestine
lipase: small intestine

Question 4

at which pH does pepsin work best ?

Answer 4

about pH 2

Question 5

at which ph does pepsin work best?

Answer 5

about pH 8

Question 6

at what happens to activity of the enzymes as pH increases?

Answer 6

Activity levels increase up to optimum pH

then fall fast.

Question 7

Explain why this change in activity happens .

Answer 7

Increase in pH affects shape of active site of enzyme
so it no longer bonds to the substrate.
Enzyme ultimately denatured
and no longer catalyses reaction.

Question 8

Explain the importance of the digestion of food in terms of the molecules involved and the role of enzymes in the gut

Answer 8

Large insoluble molecules in food cannot be absorbed into the blood.
They have to be broken down to form small insoluble molecules that
can be absorbed.
Role of enzymes is to catalyse breakdown of food
so food can be digested at the right speed
and in the right region of the gut
to be absorbed and used by the body.