Chapter 5: Enzymes

Question 1

Define ‘catalyst’

Answer 1

A substance that increases the rate of a chemical reaction and is not changed by the reaction

Question 2

Define ‘enzyme’

Answer 2

Proteins that are involved in all metabolic reactions, where they function as biological catalysts

Question 3

What are the roles of enzymes? (2 points)

Answer 3

1. For digestion, digestive enzymes are present in the alimentary canal, e.g. amylase breaks down starch into maltose, protease breaks down protein into amino acids
2. For growth, starch in germinating seeds is broken down into glucose, which provides energy for growth

Question 4

Explain enzyme action

Answer 4

The substrate fits and binds to the active site of the enzyme, forming an enzyme-substrate complex, and it produces the product, which breaks away from the enzyme

Question 5

What are the effects of changes in temperature on enzyme activity?

Answer 5

If too low, kinetic energy is lower, which decreases the collision chance between the enzyme and substrate; however, if too high, the enzyme becomes denatured and the active site cannot fit the substrate

Question 6

What are the effects of changes in pH value on enzyme activity?

Answer 6

Extreme pH values lead to denatured enzymes