AS Level Enzymes

Two enzymes, X and Y, were used in an experiment.

Enzyme X was from bacteria that live in rivers and lakes at temperatures from 5°C to 20°C.

Enzyme Y was from bacteria that live in hot water springs at temperatures from 40°C to 85°C.

The experiment measured the concentration of product produced by each enzyme at temperatures between 0°C and 100°C after 5 minutes.

Which graph shows the results?

• 
• 
• 
• 

The graphs show the effects of temperature and pH on enzyme activity.

Which statement is a correct explanation of the enzyme activity?

• At P, hydrogen bonds are formed between enzyme and substrate.

• At Q, the kinetic energy of enzyme and substrate is highest.

• At R, disulfide bonds in the enzyme begin to break.

• At S, the enzyme is completely denatured.

The diagram shows the mass of product formed over time in three reactions using the same substrate and enzyme.

The volumes of substrate, enzyme and temperature were kept constant in each reaction.

Which statement explains the difference in these reactions?

• The pH in reactions 2 and 3 has denatured the enzyme.

• There is a non-competitive inhibitor present in reaction 3.

• There is the highest concentration of enzyme in reaction 1.

• There is the highest concentration of substrate in reaction 1.

Which statements are true about the optimum temperature of all enzymes?

1 It is the temperature at which the enzymes work best.

2 It is the highest temperature at which the enzyme will work.

3 It is between 35 °C and 40 °C.

• 1, 2 and 3

• 2 and 3 only

• 1 only

• 3 only

Which levels of protein structure are always involved when competitive and non-competitive

inhibitors bind to enzymes?

• A

• B

• C

• D

Which statements are true about the optimum temperature of all enzymes?

1 It is the temperature at which the enzymes work best.

2 It is the highest temperature at which the enzyme will work.

3 It is between 35°C and 40°C.

• 1, 2 and 3

• 2 and 3 only

• 1 only

• 3 only

The graph shows how enzymes affect reactions in cells. Which statement best summarizes the information shown in the graph?

• Enzymes increase the energy of the reactants.
• Enzymes decrease the energy level of the products.
• Enzyme decrease the activation energy of the reaction.
• Enzymes reverse the direction of the reaction.

Tags

NGSS.HS-PS1-4

Based on the graph, what is the optimal temperature for this enzyme? 

• 15^oC
• 40^oC
• 30^oC
• 35^oC

Tags

NGSS.HS-PS1-5

In the diagram, what is letter A? 

• product
• substrate
• enzyme-substrate complex
• active site

Enzymes are...

• nucleic acids
• proteins
• lipids
• carbohydrates

Tags

NGSS.MS-LS1-7