Question 1

Which of the following statements best describes the effect of an enzyme on the activation energy ($$E_a) $$and the equilibrium constant ($$K_{eq}) of a $$biochemical reaction?

Accepted Answer

Enzymes lower $$E_a$$ but do not change $$K_{eq}.$$

Question 2

Which class of enzyme catalyzes the transfer of functional groups between molecules, such as kinases?

Accepted Answer

Transferases

Question 3

Apoenzyme refers to:

Accepted Answer

The inactive protein component of an enzyme that requires a cofactor

Question 4

Which of the following best describes the Michaelis constant ($$K_M$$)?

Accepted Answer

$$K_M is $$the substrate concentration at which the reaction velocity is half-maximal.

Question 5

Given the Michaelis-Menten equation $$v = \frac{V_{max}[S]}{K_M + [S]}$$, what is the value of $$v$$ when $$[S] = K_M$$?

Accepted Answer

$$v = \frac{V_{max}}{2}$$

Question 6

Which of the following is true regarding competitive inhibition?

Accepted Answer

Vmax remains unchanged, Km increases.

Question 7

A Lineweaver-Burk plot is a double reciprocal plot of which variables?

Accepted Answer

$$1/[S]$$ \, vs. \, $$1/v$$

Question 8

Which of the following best describes the turnover number ($$k_{cat}) of an $$enzyme?

Accepted Answer

The number of substrate molecules converted to product per enzyme molecule per unit time when the enzyme is saturated with substrate.

Question 9

Which of the following enzymes has the highest $$k_{cat}$$ value according to the provided data?

Accepted Answer

Catalase

Question 10

What is the effect of a noncompetitive inhibitor on $$V_{max}$$ and $$K_M$$?

Accepted Answer

$$V_{max}$$ decreases, $$K_M$$ remains unchanged (in pure noncompetitive inhibition)

Question 11

Which of the following best describes the catalytic efficiency of an enzyme?

Accepted Answer

$$k_{cat} / K_M$$

Question 12

Which of the following statements about uncompetitive inhibition is correct?

Accepted Answer

Both $$V_{max}$$ and $$K_M$$ decrease.

Question 13

Which of the following is a real-world example of an irreversible enzyme inhibitor?

Accepted Answer

Aspirin inhibiting cyclooxygenase (COX)

Question 14

Which metal ion is commonly required as a cofactor for cytochrome oxidase?

Accepted Answer

Cu$$^{2+}$$

Question 15

If an enzyme-catalyzed reaction has a $$V_{max} of$$ $$100 \, \mu M/min$$ and a $$K_M of$$ $$10 \, \mu M$$, what is the initial velocity ($$v_0) $$when $$[S] = 10 \, \mu M$$?

Accepted Answer

$$v_0 = 50$$ \, \mu M/min$$

Question 16

Which of the following best explains why the Hanes-Woolf plot is often preferred over the Lineweaver-Burk plot for determining enzyme kinetic parameters?

Accepted Answer

It produces smaller and more consistent errors across the plot.

Question 17

Which of the following is a characteristic of a 'perfect enzyme'?

Accepted Answer

Its $$k_{cat}/K_M$$ ratio approaches the diffusion limit ($$10^8$$–$$10^9 M$^{-1}s$^{-1}).$$

Question 18

Which of the following statements about enzyme active sites is FALSE?

Accepted Answer

Active sites are formed by amino acid residues that are always adjacent in the primary sequence.

Question 19

Which of the following best describes the effect of increasing enzyme concentration on the initial velocity ($$v_0) of a $$reaction, assuming substrate is not limiting?

Accepted Answer

Initial velocity increases linearly with enzyme concentration.

Comprehensive Study Notes: Enzyme Kinetics and Enzyme Inhibition

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