Question 1

Which of the following best explains why water has a high specific heat compared to other solvents?

Accepted Answer

Water's high specific heat is due to extensive hydrogen bonding between molecules, which absorbs energy when disrupted.

Question 2

Which of the following weak interactions is primarily responsible for the stabilization of nonpolar molecules in aqueous solution?

Accepted Answer

Hydrophobic interactions driven by entropy gain of the solvent

Question 3

A solution contains a weak acid, HA, and its conjugate base, A-. If the pH of the solution equals the pKa of the acid, what is the ratio of $$[A^-] to$$ $$[HA]$$?

Accepted Answer

$$[A^-]/[HA] = 1$$

Question 4

Which functional group is most likely to act as a buffer in physiological pH due to its ability to accept and donate protons?

Accepted Answer

Carboxyl

Question 5

A protein has an isoelectric point (pI) of 5.5. At pH 7.0, what is the net charge of the protein?

Accepted Answer

The protein will have a net negative charge.

Question 6

Which of the following statements about amphipathic molecules is correct?

Accepted Answer

They contain both hydrophilic and hydrophobic regions, allowing them to form structures like micelles and bilayers.

Question 7

Which equation allows you to calculate the pH of a solution containing a weak acid and its conjugate base?

Accepted Answer

$$\mathrm{pH} = \mathrm{p}K_a + \log\left(\frac{[A^-]}{[HA]}\right)$$

Question 8

Which of the following best describes the role of the hydration shell in biological systems?

Accepted Answer

It is a shell of appropriately oriented water molecules around charged or dipolar molecules, stabilizing them in solution.

Question 9

Which of the following is a correct statement about the relationship between ionic strength and protein solubility?

Accepted Answer

Increasing ionic strength can initially increase protein solubility, but at high ionic strength, it can decrease solubility due to 'salting out'.

Question 10

Which of the following is NOT a property that emerges from the structure of water?

Accepted Answer

Low surface tension

Question 11

A weak acid has a $$\mathrm{p}K_a of 4.8. If $$the ratio of $$[A^-] to$$ $$[HA] is 10$$, what is the pH of the solution?

Accepted Answer

$$\mathrm{pH} = 5.8$$

Question 12

Which of the following best describes a zwitterion?

Accepted Answer

A dipolar ion that contains both positive and negative charges but is overall neutral.

Question 13

Which of the following functional groups is NOT commonly found in biochemistry?

Accepted Answer

Nitro

Question 14

Which of the following statements about the Henderson-Hasselbalch equation is correct?

Accepted Answer

It relates the pH of a solution to the ratio of conjugate base to acid and the acid's $$\mathrm{p}K_a.$$

Question 15

Which of the following is a consequence of water's high dielectric constant?

Accepted Answer

It decreases the strength of ionic interactions, allowing salts to dissolve more easily.

Question 16

Which of the following best describes a polyprotic weak acid?

Accepted Answer

An acid that can donate more than one proton.

Question 17

Which of the following is a correct statement about buffer capacity?

Accepted Answer

Buffer capacity is highest when the pH equals the $$\mathrm{p}K_a of $$the buffer and the concentrations of acid and base are high.

Question 18

Which of the following is an example of a condensation reaction in biochemistry?

Accepted Answer

Formation of a peptide bond between two amino acids

Question 19

Which of the following best describes the counterion atmosphere around a macromolecule?

Accepted Answer

A cloud of oppositely charged small ions that affects solubility of macromolecules in solution.

Water, Weak Interactions, and Functional Groups in Biochemistry

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