Question 1

Which of the following statements best explains why hemoglobin does not release all four of its bound O$$_2$$ molecules to tissues under normal physiological conditions?

Accepted Answer

The partial pressure of oxygen in tissues is not low enough to cause complete unloading of O$$_2$$ from hemoglobin.

Question 2

The Bohr effect describes the influence of which variable on hemoglobin's affinity for oxygen?

Accepted Answer

pH

Question 3

Which of the following is NOT a function or property of enzymes?

Accepted Answer

Enzymes are consumed during the reaction.

Question 4

Which of the following best describes the effect of an enzyme on the activation energy ($$\Delta G$$^{\ddagger}$$) and the equilibrium constant (K$$_{eq}$$) of a reaction?

Accepted Answer

Enzymes decrease $$\Delta G$$^{\ddagger}$$ but do not affect K$$_{eq}$$.

Question 5

A patient with phenylketonuria (PKU) has a deficiency in which enzyme, and what is the biochemical consequence?

Accepted Answer

Phenylalanine hydroxylase; buildup of phenylalanine in the body

Question 6

Which of the following equations correctly represents the Michaelis-Menten equation for a simple enzyme-catalyzed reaction?

Accepted Answer

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

Question 7

In a Lineweaver-Burk plot, what does the x-intercept represent?

Accepted Answer

The negative reciprocal of $$K_m$$

Question 8

Which of the following best describes competitive inhibition in enzyme kinetics?

Accepted Answer

The inhibitor binds to the active site, increasing apparent $$K_m$$ but not affecting $$V_{max}.$$

Question 9

Which catalytic mechanism involves the formation of a transient covalent bond between the enzyme and substrate?

Accepted Answer

Covalent catalysis

Question 10

A Lineweaver-Burk plot of a two-substrate enzyme reaction shows a family of lines that intersect. What does this indicate about the reaction mechanism?

Accepted Answer

A sequential mechanism with a ternary complex

Question 11

Which of the following statements about $$K_m is $$correct?

Accepted Answer

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

Question 12

Which of the following best describes the physiological significance of 2,3-Bisphosphoglycerate (2,3-BPG) in hemoglobin function?

Accepted Answer

2,3-BPG decreases hemoglobin's affinity for oxygen, facilitating oxygen release in tissues.

Question 13

Which of the following is true regarding the turnover number ($$k_{cat}) of an $$enzyme?

Accepted Answer

$$k_{cat} is $$the number of substrate molecules converted to product per enzyme molecule per second.

Question 14

Which of the following statements about enzyme-substrate binding is correct?

Accepted Answer

Enzymes bind the transition state more tightly than the substrate.

Question 15

Which of the following is a consequence of uncompetitive inhibition?

Accepted Answer

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

Question 16

Which of the following best describes the rate equation for a first-order reaction?

Accepted Answer

$$V = k[S]$$

Question 17

Which of the following is a key advantage of biocatalysis (enzymes) over inorganic catalysts?

Accepted Answer

Enzymes provide greater reaction specificity and can be regulated.

Question 18

Which of the following best describes the effect of a mixed inhibitor on enzyme kinetics?

Accepted Answer

It decreases $$V_{max}$$ and can either increase or decrease $$K_m.$$

Question 19

Which of the following is true about the specificity constant ($$k_{cat}/K_m) $$for enzymes?

Accepted Answer

It is a measure of enzyme efficiency and is limited by the rate of substrate diffusion.

Chapter 6

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