Enzymes AS Level

The solid line on the graph represents the product formed over time for a reaction in a cell.

Which other line represents the effect of adding the enzyme for this reaction?

What is the factor limiting the rate in region X?

• substrate concentration

• enzyme concentration

• temperature

• number of active sites

What would limit the initial rate of reaction at point X?

• enzyme concentration

• pH

• substrate concentration

• temperature

• A

• B

• C

• D

Which statements describe some enzyme actions?

1 Enzymes hold reacting molecules so that their reactive groups are close together.

2 In an enyzme-catalysed reaction, more molecules have sufficient energy to react than without enzyme.

3 Reactions catalysed by enzymes take place at a lower temperature than they would without the enzyme.

• 1, 2 and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

Which region on the graph shows the activation energy of an enzyme-catalysed reaction?

• A

• B

• C

• D

• A

• B

• C

• D

Which bond in tertiary structure of an enzyme is likely broken by change of pH?

• ionic

• hydrogen

• peptide

• disulfide

Match the following.

• proteins

• the class of compounds that make up enzymes

• fats

• the class of compounds that lipase breaks

• intracellular

• the shapes of an acitve site and its substrate.

• induced-fit hypothesis

• enzymes that work inside cells

• complementary

• enzymes change active site and mould over substrates

When a substrate is about to enter ​ (a)   of an enzyme, it induces shape change to it so they become ​ (b)   to each other. The binding complex is called ​ (c)   . The substrate interacts with the ​ (d)   of the amino acids there. After reaction is finished, the ​ (e)   leave the enzyme.

• active site
• complementary
• enzyme-substrate complex
• R-groups
• products
• substrate
• carboxyl group