Question 1

Which of the following best describes the primary function of an enzyme in a biological reaction?

Accepted Answer

To lower the activation energy required for the reaction.

Question 2

Which class of enzyme catalyzes the transfer of a phosphoryl group (–PO$$_3$$^{2-}$$) between substrates?

Accepted Answer

Kinase

Question 3

A reaction catalyzed by alcohol dehydrogenase is shown below:

$$\mathrm{CH_3CH_2OH + NAD^+ \longleftrightarrow CH_3CHO + NADH + H^+}$$

Which class of enzyme is alcohol dehydrogenase?

Accepted Answer

Oxidoreductase

Question 4

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Highly specific enzymes catalyze one type of reaction for a single substrate.

Question 5

Which subclass of hydrolases is responsible for breaking peptide bonds in proteins?

Accepted Answer

Proteases

Question 6

Which effect describes how enzymes lower the activation energy by inducing a strain on the bonds of the substrate?

Accepted Answer

Energy effect

Question 7

Which enzyme class catalyzes the rearrangement of atoms in a substrate to produce an isomer?

Accepted Answer

Isomerase

Question 8

Which class of enzymes requires ATP hydrolysis to provide energy for the reaction to occur?

Accepted Answer

Ligases

Question 9

Which model best explains how substrate binding triggers a conformational change in the enzyme?

Accepted Answer

Induced fit model

Question 10

A patient is diagnosed with a genetic mutation that causes their proteases to lose function at pH 2 but remain active at pH 8. Which digestive enzyme is most likely affected?

Accepted Answer

Pepsin

Question 11

Which of the following statements about enzyme activity and temperature is correct?

Accepted Answer

Enzyme activity is highest at an optimum temperature and decreases at higher temperatures due to denaturation.

Question 12

Which of the following best describes the effect of increasing substrate concentration on enzyme-catalyzed reaction rate when enzyme concentration is constant?

Accepted Answer

The reaction rate increases and then levels off at a maximum value.

Question 13

Which of the following is true regarding the fate of an enzyme after it catalyzes a reaction?

Accepted Answer

The enzyme is recycled and can catalyze another reaction.

Question 14

Which of the following is a coenzyme commonly required by dehydrogenases?

Accepted Answer

NAD$$^+$$

Question 15

A scientist is studying an enzyme that catalyzes the addition of CO$$_2 to $$pyruvate to form oxaloacetate, using ATP. Which enzyme class does this enzyme belong to?

Accepted Answer

Ligase

Question 16

Which of the following best describes the role of a cofactor in enzyme catalysis?

Accepted Answer

A cofactor is a nonprotein substance required for enzyme activity.

Question 17

Which of the following scenarios best illustrates the concept of enzyme saturation?

Accepted Answer

At high substrate concentrations, all enzyme active sites are occupied and the reaction rate reaches a maximum.

Question 18

Which of the following statements about the induced fit model is correct?

Accepted Answer

Substrate binding causes a conformational change in the enzyme.

Question 19

Which of the following is NOT a subclass of hydrolases?

Accepted Answer

Kinases

Question 20

A patient is given a drug that inhibits all kinases in their body. Which process would be most directly affected?

Accepted Answer

Transfer of phosphoryl groups between molecules

lec 10 Enzyme Classification, Mechanisms, and Regulation

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