Question 1

Which of the following best describes the primary focus of biochemistry as a scientific discipline?

Accepted Answer

The study of the molecular basis of living systems.

Question 2

Which of the following elements is NOT considered a major element in biological systems?

Accepted Answer

Sodium (Na)

Question 3

Which functional group is present in all amino acids and is responsible for their acidic properties?

Accepted Answer

Carboxyl group ($$\mathrm{-COOH})$$

Question 4

Which type of linkage connects monosaccharides in polysaccharides?

Accepted Answer

Glycosidic bond

Question 5

What is the main reason water is an excellent solvent for polar and ionic substances?

Accepted Answer

Water is highly polar and forms hydrogen bonds.

Question 6

Which of the following statements about hydrogen bonds in water is CORRECT?

Accepted Answer

Hydrogen bonds in water are dynamic and fluctuate rapidly.

Question 7

Given the following equilibrium for a weak acid: $$\mathrm{HA \rightleftharpoons A^- + H^+}$$, what is the expression for the acid dissociation constant ($$K_a$$)?

Accepted Answer

$$K_a = \frac{[A^-][H^+]}{[HA]}$$

Question 8

At what pH does a weak acid exist as exactly 50% protonated and 50% deprotonated?

Accepted Answer

When $$\mathrm{pH = pK_a}$$

Question 9

Which of the following best explains why non-polar segments of biological molecules are excluded from water?

Accepted Answer

Non-polar segments cannot interact favorably with water, leading to the hydrophobic effect.

Question 10

A solution has $$[H^+] = 1 	imes 10$$^{-5}$$ M. What is the pH of this solution?

Accepted Answer

pH = 5

Question 11

Which of the following is a correct statement about the ionization state of a generic amino acid at pH 7?

Accepted Answer

The amino group is protonated ($$\mathrm{NH_3$^+}) $$and the carboxyl group is deprotonated ($$\mathrm{COO^-}).$$

Question 12

Which of the following linkages is found in proteins?

Accepted Answer

Peptide bond

Question 13

Which property of water is most critical for maintaining the structure of biological macromolecules?

Accepted Answer

Its extensive hydrogen bonding network.

Question 14

A buffer solution is prepared using a weak acid with $$pK_a = 4.8. At $$what pH will the buffer have its maximum buffering capacity?

Accepted Answer

pH = 4.8

Question 15

Which of the following best describes the relationship between monomers and polymers in biological systems?

Accepted Answer

Polymers are formed by the covalent linkage of monomers in a specific orientation.

Question 16

Which of the following is a correct application of the Henderson-Hasselbalch equation?

Accepted Answer

Determining the ratio of conjugate base to acid in a buffer system.

Question 17

Which of the following statements about the structure of ice compared to liquid water is TRUE?

Accepted Answer

Each water molecule in ice forms four hydrogen bonds in a regular lattice.

Question 18

Which of the following best explains why the pH of blood is tightly regulated in humans?

Accepted Answer

Enzyme activity and protein structure are highly sensitive to changes in pH.

Question 19

Which of the following is the correct formula for calculating pH?

Accepted Answer

$$\mathrm{pH = -log_{10}[H^+]}$$

Question 20

Which of the following best describes a zwitterion?

Accepted Answer

A molecule with both positive and negative charges but is overall neutral.

Introductory Biochemistry: Foundations of Biomolecules and Water

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