Question 1

Which of the following best describes the primary function of buffers in biological systems?

Accepted Answer

Buffers resist changes in pH by neutralizing added acids or bases.

Question 2

A patient presents with metabolic acidosis. Which buffer system is most important in maintaining blood pH?

Accepted Answer

Bicarbonate buffer system

Question 3

Which of the following equations correctly represents the Henderson-Hasselbalch equation for calculating the pH of a buffer solution?

Accepted Answer

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

Question 4

Which statement best explains why enzymes are highly specific for their substrates?

Accepted Answer

Enzymes have active sites with unique three-dimensional shapes that complement specific substrates.

Question 5

A mutation changes the amino acid sequence of an enzyme’s active site. What is the most likely consequence?

Accepted Answer

The enzyme may lose its substrate specificity and catalytic activity.

Question 6

Which of the following is a correct statement about the relationship between Gibbs free energy ($$\Delta G) $$and spontaneity of a reaction?

Accepted Answer

A reaction with $$\Delta G \u003c 0 is $$spontaneous.

Question 7

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP serves as the primary energy currency, coupling exergonic and endergonic reactions.

Question 8

A researcher measures the rate of an enzyme-catalyzed reaction at different substrate concentrations and plots the data. Which equation describes the relationship between reaction velocity ($$v) $$and substrate concentration ($$[S]) $$for Michaelis-Menten kinetics?

Accepted Answer

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

Question 9

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

Accepted Answer

Storing genetic information

Question 10

A patient is diagnosed with sickle cell anemia. Which molecular change is responsible for this disease?

Accepted Answer

A substitution of valine for glutamic acid in the beta chain of hemoglobin

Question 11

Which of the following statements about the central dogma of molecular biology is correct?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 12

Which of the following best explains why phospholipids form bilayers in aqueous environments?

Accepted Answer

Phospholipids have both hydrophilic heads and hydrophobic tails, causing them to arrange in bilayers.

Question 13

Which of the following is a correct statement about the structure of DNA?

Accepted Answer

DNA is a double helix with antiparallel strands held together by hydrogen bonds between complementary bases.

Question 14

A competitive inhibitor of an enzyme will have which of the following effects on Michaelis-Menten kinetics?

Accepted Answer

No change in $$V_{max}$$, but increase in $$K_m$$

Question 15

Which of the following is the best example of an anabolic pathway?

Accepted Answer

Fatty acid synthesis

Question 16

Which of the following statements about the tertiary structure of proteins is correct?

Accepted Answer

Tertiary structure results from interactions between side chains, including hydrogen bonds, ionic bonds, and hydrophobic interactions.

Question 17

A patient with a deficiency in the enzyme hexokinase is unable to efficiently convert glucose to glucose-6-phosphate. Which metabolic pathway is directly affected?

Accepted Answer

Glycolysis

Question 18

Which of the following is a correct statement about the role of NAD+ in cellular respiration?

Accepted Answer

NAD+ is reduced to NADH, which carries electrons to the electron transport chain.

Question 19

Which of the following best describes the induced fit model of enzyme-substrate interaction?

Accepted Answer

The enzyme’s active site changes shape to better fit the substrate upon binding.

Biochemistry I (CHEM251) Fall 2023 Syllabus and Study Guide

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