Question 1

Which of the following best explains why sodium chloride (NaCl) dissolves readily in water?

Accepted Answer

The polarity of water allows it to stabilize the ions formed from NaCl dissociation.

Question 2

Which equation describes the relationship between pH and pKa in a buffer system?

Accepted Answer

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

Question 3

A titration curve of a weak acid shows a buffer region. What is the significance of the buffer region?

Accepted Answer

It is the region where the solution resists changes in pH upon addition of small amounts of acid or base.

Question 4

Which of the following best describes the Gibbs free energy change ($$\Delta G) $$for a spontaneous reaction?

Accepted Answer

$$\Delta G is $$negative

Question 5

In cellular metabolism, why is ATP hydrolysis often coupled to energetically unfavorable reactions?

Accepted Answer

ATP hydrolysis provides a negative $$\Delta G to $$drive unfavorable reactions forward.

Question 6

Which of the following is NOT a function of carbohydrates in biological systems?

Accepted Answer

Catalysis of chemical reactions

Question 7

Which type of lipid is most likely to be found in membrane rafts and why?

Accepted Answer

Cholesterol, because it stabilizes the membrane and is enriched in rafts.

Question 8

Which equation is used to describe enzyme kinetics according to the Michaelis-Menten model?

Accepted Answer

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

Question 9

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Increasing $$K_m$$ without affecting $$V_{max}$$

Question 10

Which of the following amino acids is most likely to be found in the active site of an enzyme that catalyzes acid-base reactions?

Accepted Answer

Glutamic acid

Question 11

Which statement best describes the difference between pyrimidines and purines in nucleic acids?

Accepted Answer

Purines have a double-ring structure, while pyrimidines have a single-ring structure.

Question 12

Which of the following is a consequence of a frameshift mutation in a protein-coding gene?

Accepted Answer

The reading frame is altered, potentially changing all downstream amino acids.

Question 13

Which process occurs in the nucleus of eukaryotic cells but not in prokaryotic cells?

Accepted Answer

mRNA processing (such as splicing)

Question 14

What is the function of the 5' guanosine cap in eukaryotic mRNA?

Accepted Answer

It protects mRNA from degradation and assists in ribosome binding.

Question 15

Which of the following best describes the role of the spliceosome?

Accepted Answer

It removes introns from pre-mRNA during mRNA processing.

Question 16

Which of the following is a real-world example of a genetic disease caused by a single nucleotide mutation?

Accepted Answer

Sickle cell anemia

Question 17

Which of the following best explains the effect of temperature on enzyme activity?

Accepted Answer

Enzyme activity increases with temperature up to an optimum, then decreases due to denaturation.

Question 18

Which of the following is a function of membrane rafts in cells?

Accepted Answer

They facilitate cell signaling by clustering specific proteins and lipids.

Question 19

Which of the following best describes the effect of a silent mutation?

Accepted Answer

It does not change the amino acid sequence of the protein.

Question 20

Which of the following is true about the structure of DNA in eukaryotic chromosomes?

Accepted Answer

DNA is linear and packaged with histone proteins into chromatin.

Pharmaceutical Biochemistry PC 1112: Comprehensive Study Notes

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