Question 1

Which of the following statements best describes the function of an enzyme's active site?

Accepted Answer

It is the region where substrates bind and undergo a chemical reaction.

Question 2

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 3

Which of the following is true regarding the Michaelis-Menten constant ($K_m$)?

Accepted Answer

It is the substrate concentration at which the reaction rate is half of $V_{max}$.

Question 4

If a non-competitive inhibitor is added to an enzyme-catalyzed reaction, what is the expected effect on $V_{max}$ and $K_m$?

Accepted Answer

$V_{max}$ decreases, $K_m$ remains unchanged.

Question 5

Which of the following equations represents the Michaelis-Menten equation for enzyme kinetics?

Accepted Answer

$v = \frac{V_{max}[S]}{K_m + [S]}$

Question 6

A patient is given a drug that acts as a competitive inhibitor for a key metabolic enzyme. Which of the following changes would you expect in the enzyme kinetics?

Accepted Answer

$K_m$ increases, $V_{max}$ remains the same.

Question 7

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The active site has a unique three-dimensional structure that fits only specific substrates.

Question 8

In a Lineweaver-Burk plot, which of the following changes would indicate the presence of a competitive inhibitor?

Accepted Answer

The $x$-intercept moves closer to zero, but the $y$-intercept remains the same.

Question 9

Which property distinguishes a non-competitive inhibitor from a competitive inhibitor?

Accepted Answer

A non-competitive inhibitor binds to a site other than the active site.

Question 10

A researcher observes that adding more substrate does not restore the original reaction rate in the presence of an inhibitor. What type of inhibition is most likely occurring?

Accepted Answer

Non-competitive inhibition

Question 11

Which of the following statements about $V_{max}$ is correct?

Accepted Answer

$V_{max}$ is the maximum rate achieved by the system, at saturating substrate concentration.

Question 12

Which of the following best describes the effect of an enzyme on the activation energy of a reaction?

Accepted Answer

It lowers the activation energy, increasing the reaction rate.

Question 13

A mutation in an enzyme's active site reduces its affinity for its substrate. Which kinetic parameter is most likely to increase as a result?

Accepted Answer

$K_m$

Question 14

Which of the following is a real-life example of competitive inhibition?

Accepted Answer

Methanol poisoning treated with ethanol, which competes for alcohol dehydrogenase.

Question 15

If an enzyme-catalyzed reaction is proceeding at $V_{max}$, what can be said about the substrate concentration?

Accepted Answer

The substrate concentration is much greater than $K_m$.

Question 16

A patient with a genetic mutation has an enzyme with a $K_m$ value that is twice as high as normal. What does this suggest about the enzyme's affinity for its substrate?

Accepted Answer

The enzyme has a lower affinity for its substrate.

Question 17

Which of the following best describes the effect of a competitive inhibitor on a Lineweaver-Burk plot?

Accepted Answer

The slope increases, but the $y$-intercept remains the same.

Question 18

Which of the following is NOT a property of enzymes?

Accepted Answer

They are consumed during the reaction.

Question 19

A scientist is studying an enzyme-catalyzed reaction and finds that the presence of a certain inhibitor does not change the $K_m$ but decreases the $V_{max}$. What type of inhibitor is most likely present?

Accepted Answer

Non-competitive inhibitor

Enzyme Function and Inhibition: Key Concepts and Properties

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