Question 1

Which of the following best describes the amphipathic nature of biomolecules such as phospholipids in biological membranes?

Accepted Answer

They have both hydrophilic and hydrophobic regions, enabling membrane formation.

Question 2

A solution contains a weak acid and its conjugate base. Which equation would you use to calculate the pH of this buffer system?

Accepted Answer

The Henderson-Hasselbalch equation: $$pH = pK_a + \log \left( \frac{[A^-]}{[HA]} \right)$$

Question 3

Which statement about the peptide bond in proteins is correct?

Accepted Answer

It has partial double-bond character, restricting rotation.

Question 4

A patient’s blood pH is measured at 7.1. Which of the following best describes their condition?

Accepted Answer

Acidosis, because the pH is below the normal physiological range.

Question 5

Which level of protein structure is primarily determined by hydrogen bonding between backbone atoms?

Accepted Answer

Secondary structure

Question 6

Which of the following is a correct application of the Michaelis-Menten equation in enzyme kinetics?

Accepted Answer

It models the initial velocity of an enzyme-catalyzed reaction as $$v = \frac{V_{max}[S]}{K_m + [S]}.$$

Question 7

Which of the following statements about prions is correct?

Accepted Answer

Prions are misfolded proteins that can induce misfolding in normal proteins.

Question 8

A protein is found to have four distinct polypeptide chains assembled together. What is the highest level of structure present?

Accepted Answer

Quaternary structure

Question 9

Which of the following best explains the role of chaperones in protein folding?

Accepted Answer

They prevent aggregation and assist in proper folding of polypeptides.

Question 10

Which of the following is a characteristic of fibrous proteins such as collagen?

Accepted Answer

They provide structural support and have elongated, rope-like shapes.

Question 11

Which of the following is true regarding enzyme inhibition?

Accepted Answer

Irreversible inhibitors bind covalently and permanently inactivate enzymes.

Question 12

Which of the following amino acids is most likely to be found in the interior of a globular protein?

Accepted Answer

Leucine

Question 13

Which of the following best describes the proximity effect in enzyme catalysis?

Accepted Answer

Enzymes increase reaction rates by bringing substrates into close spatial arrangement.

Question 14

Which of the following is a correct statement about the role of water in biological systems?

Accepted Answer

Water’s polarity allows it to form hydrogen bonds, making it an excellent solvent for biomolecules.

Question 15

A protein’s tertiary structure is stabilized by which of the following interactions?

Accepted Answer

Hydrogen bonds, ionic interactions, hydrophobic effects, and disulfide bridges.

Question 16

Which of the following is a correct description of the action of a catalyst?

Accepted Answer

It lowers the activation energy, increasing the reaction rate without being consumed.

Question 17

Which of the following is true about the specificity of enzyme-substrate recognition?

Accepted Answer

It results from precise molecular recognition between the enzyme and substrate.

Question 18

Which of the following statements about secondary valence forces in proteins is correct?

Accepted Answer

They include hydrogen bonds and van der Waals interactions that stabilize secondary and tertiary structures.

Question 19

Which of the following is a correct statement about zymogens?

Accepted Answer

Zymogens are inactive precursors that require proteolytic cleavage for activation.

Question 20

A biochemist is studying the effect of a competitive inhibitor on an enzyme. Which of the following changes would be observed in the Michaelis-Menten plot?

Accepted Answer

The $$K_m$$ increases, but $$V_{max}$$ remains unchanged.

Core Concepts in Biochemistry: Biomolecules, Protein Structure, and Enzyme Mechanisms

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