Question 1

Which of the following best explains why hemoglobin can efficiently transport oxygen in the blood, while myoglobin cannot?
Correct answer: Hemoglobin exhibits cooperative binding of oxygen, allowing for efficient loading and unloading, whereas myoglobin does not.

Accepted Answer

Hemoglobin exhibits cooperative binding of oxygen, allowing for efficient loading and unloading, whereas myoglobin does not.

Question 2

A solution contains 0.1 M acetic acid (pKa = 4.76) and 0.2 M sodium acetate. What is the pH of the solution? (Use the Henderson-Hasselbalch equation.)
Correct answer: pH = 5.06

Accepted Answer

pH = 5.06

Question 3

Which of the following statements about enzyme catalysis is correct?
Correct answer: Enzymes lower the activation energy, thereby increasing the reaction rate.

Accepted Answer

Enzymes lower the activation energy, thereby increasing the reaction rate.

Question 4

A patient is diagnosed with a genetic disorder that results in a non-functional sodium-potassium ATPase. Which of the following cellular processes would be most directly affected?
Correct answer: Active transport of sodium and potassium ions across the membrane

Accepted Answer

Active transport of sodium and potassium ions across the membrane

Question 5

Which of the following best describes the primary structure of a protein?
Correct answer: The sequence of amino acids linked by peptide bonds

Accepted Answer

The sequence of amino acids linked by peptide bonds

Question 6

A competitive inhibitor of an enzyme will have which of the following effects on the Michaelis-Menten kinetic parameters?
Correct answer: No change in Vmax, but increase in Km

Accepted Answer

No change in Vmax, but increase in Km

Question 7

Which of the following best explains why phospholipids form bilayers in aqueous environments?
Correct answer: The hydrophilic heads interact with water, while the hydrophobic tails avoid water, leading to self-assembly into bilayers.

Accepted Answer

The hydrophilic heads interact with water, while the hydrophobic tails avoid water, leading to self-assembly into bilayers.

Question 8

During glycolysis, which of the following steps is an example of substrate-level phosphorylation?
Correct answer: Conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate

Accepted Answer

Conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate

Question 9

Which of the following is a correct statement about the structure of DNA?
Correct answer: The bases are paired via hydrogen bonds, with adenine pairing with thymine.

Accepted Answer

The bases are paired via hydrogen bonds, with adenine pairing with thymine.

Question 10

A mutation causes a single amino acid substitution in the active site of an enzyme, resulting in a dramatic decrease in catalytic efficiency. Which property of enzymes does this best illustrate?
Correct answer: Enzymes are highly specific for their substrates and active site structure is critical for function.

Accepted Answer

Enzymes are highly specific for their substrates and active site structure is critical for function.

Question 11

Which of the following best describes the role of water in biochemical reactions?
Correct answer: Water can act as both a reactant and a product in hydrolysis and condensation reactions.

Accepted Answer

Water can act as both a reactant and a product in hydrolysis and condensation reactions.

Question 12

A researcher is studying a protein that denatures at high temperatures. Which of the following interactions is most likely disrupted during denaturation?
Correct answer: Hydrogen bonds and hydrophobic interactions stabilizing secondary and tertiary structure

Accepted Answer

Hydrogen bonds and hydrophobic interactions stabilizing secondary and tertiary structure

Question 13

Which of the following statements about metabolic pathways is correct?
Correct answer: Metabolic pathways are regulated at key steps, often by allosteric enzymes.

Accepted Answer

Metabolic pathways are regulated at key steps, often by allosteric enzymes.

Question 14

A solution is prepared by mixing 0.05 mol of lactic acid (pKa = 3.86) and 0.05 mol of sodium lactate in 1 L of water. What is the pH of the solution?
Correct answer: pH = 3.86

Accepted Answer

pH = 3.86

Question 15

Which of the following best explains the effect of a noncompetitive inhibitor on enzyme kinetics?
Correct answer: It decreases Vmax but does not change Km.

Accepted Answer

It decreases Vmax but does not change Km.

Question 16

Which of the following is a correct statement about the thermodynamics of biochemical reactions?
Correct answer: A reaction with ΔG = 0 is at equilibrium.

Accepted Answer

A reaction with ΔG = 0 is at equilibrium.

Question 17

Which of the following best describes the function of cholesterol in animal cell membranes?
Correct answer: Cholesterol decreases membrane fluidity at high temperatures and increases it at low temperatures.

Accepted Answer

Cholesterol decreases membrane fluidity at high temperatures and increases it at low temperatures.

Question 18

A patient with a deficiency in the enzyme hexokinase is unable to efficiently phosphorylate glucose. Which metabolic pathway is most directly affected?
Correct answer: Glycolysis

Accepted Answer

Glycolysis

Question 19

Which of the following statements about nucleotides is correct?
Correct answer: Nucleotides are composed of a nitrogenous base, a pentose sugar, and one or more phosphate groups.

Accepted Answer

Nucleotides are composed of a nitrogenous base, a pentose sugar, and one or more phosphate groups.

Question 20

Which of the following best explains why enzymes are highly specific for their substrates?
Correct answer: The active site of an enzyme is complementary in shape and chemical properties to its substrate.

Accepted Answer

The active site of an enzyme is complementary in shape and chemical properties to its substrate.

Key Concepts and Structure of Biochemistry I (BCH4053.0001)

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