Question 1

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

Accepted Answer

It lowers the activation energy $$\Delta G$$^{\ddagger}$$, thereby increasing the reaction rate.

Question 2

Which enzyme class does hexokinase belong to, and what type of reaction does it catalyze?

Accepted Answer

Transferase; transfer of a phosphate group

Question 3

Given the equation $$K = e$$^{\left(\frac{-\Delta G^\circ}$${RT}\right)}$$, what happens to the equilibrium constant $$K if$$ $$\Delta G^\circ$$ becomes more negative?

Accepted Answer

K increases

Question 4

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzymes are specific and typically catalyze reactions for only one stereoisomer.

Question 5

A patient is prescribed captopril, a competitive inhibitor of angiotensin-converting enzyme (ACE). Which of the following best describes how captopril works?

Accepted Answer

It binds to the active site, increasing $$K_M$$ without affecting $$V_{max}.$$

Question 6

Which of the following graphs best represents a first-order reaction when plotting $$\ln [A]$$ versus time?

Accepted Answer

A straight line with a negative slope

Question 7

Which of the following is a correct statement about the effect of temperature on enzyme-catalyzed reactions?

Accepted Answer

Enzyme activity is optimal within a specific temperature range and decreases outside this range.

Question 8

Which of the following best explains why enzymes are able to accelerate reaction rates?

Accepted Answer

They stabilize the transition state, lowering $$\Delta G$$^{\ddagger}$$.

Question 9

Which enzyme class catalyzes the conversion of ethanol to acetaldehyde using NAD$$^+ as a $$cofactor?

Accepted Answer

Oxidoreductase

Question 10

Which of the following is true regarding the Michaelis-Menten equation $$v = \frac{V_{max}[S]}{K_M + [S]}$$?

Accepted Answer

At very high $$[S]$$, $$v$$ approaches $$V_{max}.$$

Question 11

Which of the following best describes the function of the 'oxyanion hole' in serine proteases?

Accepted Answer

It stabilizes the tetrahedral intermediate by hydrogen bonding.

Question 12

Which of the following is a correct statement about the effect of a competitive inhibitor on enzyme kinetics?

Accepted Answer

$$V_{max}$$ remains unchanged and $$K_M$$ increases.

Question 13

Which of the following best describes the role of biotin as a coenzyme?

Accepted Answer

It is involved in CO$$_2$$ activation and transfer.

Question 14

Which of the following is the correct sequence of events in the serine protease catalytic mechanism?

Accepted Answer

Substrate binding → formation of tetrahedral intermediate → acyl-enzyme intermediate → product release

Question 15

Which of the following is a function of the catalytic triad (Ser, His, Asp) in serine proteases?

Accepted Answer

It forms a covalent bond with the substrate, facilitating peptide bond cleavage.

Question 16

Which of the following best describes the effect of an enzyme on the transition state of a reaction?

Accepted Answer

It stabilizes the transition state, lowering the activation energy.

Question 17

Which of the following is an example of a ligase-catalyzed reaction?

Accepted Answer

Pyruvate carboxylase catalyzing the formation of oxaloacetate from pyruvate and CO$$_2$$

Question 18

Which of the following statements about enzyme regulation is correct?

Accepted Answer

Enzyme activity is regulated to ensure metabolic reactions occur at rates appropriate to cellular requirements.

Enzyme Structure, Function, and Kinetics: A Comprehensive Study Guide

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