Question 1

Which of the following best describes the role of an enzyme in a chemical reaction?

Accepted Answer

It lowers the activation energy ($$E_A) $$required for the reaction to proceed.

Question 2

Sucrase catalyzes the hydrolysis of sucrose into which two monosaccharides?

Accepted Answer

Glucose and fructose

Question 3

Refer to the following reaction: $$	ext{Sucrose} + H_2O \xrightarrow{	ext{Sucrase}} 	ext{Glucose} + 	ext{Fructose}. $$What type of enzyme is sucrase?

Accepted Answer

Hydrolase

Question 4

Which of the following statements about activation energy ($$E_A) is $$correct?

Accepted Answer

Activation energy is the energy required to break bonds in the reactants so the reaction can proceed.

Question 5

Which of the following is true regarding the effect of enzymes on the free energy change ($$\Delta G) of a $$reaction?

Accepted Answer

Enzymes do not affect $$\Delta G.$$

Question 6

Which enzyme class is responsible for transferring functional groups from one molecule to another?

Accepted Answer

Transferase

Question 7

A mutation changes a key amino acid in the active site of an enzyme from aspartic acid (Asp) to glycine (Gly). What is the most likely effect on enzyme function?

Accepted Answer

The enzyme will lose its ability to bind the substrate due to loss of charge interactions.

Question 8

Which of the following best explains why enzyme-catalyzed reactions plateau at high substrate concentrations?

Accepted Answer

All enzyme active sites are occupied, so the reaction rate cannot increase further.

Question 9

Which of the following is an example of a coenzyme?

Accepted Answer

Vitamin B6 derivative (pyridoxal phosphate)

Question 10

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 11

Which of the following strategies can overcome the effects of a competitive inhibitor?

Accepted Answer

Increasing the concentration of the substrate.

Question 12

Which of the following best describes allosteric regulation?

Accepted Answer

A molecule binds to a site other than the active site, changing enzyme activity.

Question 13

In feedback inhibition, the end product of a metabolic pathway:

Accepted Answer

Inhibits an enzyme earlier in the pathway to prevent overproduction.

Question 14

Which of the following is an example of covalent modification regulating enzyme activity?

Accepted Answer

Phosphorylation of glycogen phosphorylase

Question 15

Why do enzymes such as pepsin and trypsin have different optimal pH values?

Accepted Answer

They are found in different cellular compartments with different pH environments.

Question 16

Which of the following best describes positive cooperativity in an allosteric enzyme?

Accepted Answer

Binding of one substrate molecule increases the affinity of other active sites for substrate.

Question 17

A patient is prescribed an ACE inhibitor to treat high blood pressure. What is the mechanism of action of this drug?

Accepted Answer

It acts as a competitive inhibitor of angiotensin-converting enzyme.

Question 18

Which of the following is NOT a way that cells regulate enzyme activity?

Accepted Answer

Increasing the temperature above the enzyme's optimal range

Question 19

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is determined by the shape and chemical properties of the active site.

Bio 100 LEC Chapter 8 Modules 4-5

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