Question 1

Which of the following best describes the role of an enzyme in a biochemical reaction?

Accepted Answer

Enzymes lower the activation energy, thereby increasing the rate of the reaction.

Question 2

A patient is diagnosed with a genetic disorder that results in a nonfunctional hexokinase enzyme. Which metabolic pathway will be directly affected?

Accepted Answer

Glycolysis

Question 3

Which of the following equations correctly represents the Michaelis-Menten equation for enzyme kinetics?

Accepted Answer

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

Question 4

A competitive inhibitor affects enzyme kinetics in which of the following ways?

Accepted Answer

Increases $$K_m$$ and does not change $$V_{max}$$

Question 5

Which of the following statements about allosteric enzymes is correct?

Accepted Answer

Allosteric enzymes often display sigmoidal kinetics due to cooperative substrate binding.

Question 6

Which of the following is a correct structural difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose, while RNA contains ribose.

Question 7

A patient with a deficiency in the enzyme lactase is unable to digest which of the following carbohydrates?

Accepted Answer

Lactose

Question 8

Which of the following best describes the structure of glycogen?

Accepted Answer

A highly branched polymer of $$\alpha-D-$$glucose linked by $$\alpha-1$$,4 and $$\alpha-1$$,6 glycosidic bonds.

Question 9

Which of the following is a function of lipids in biological membranes?

Accepted Answer

They form a hydrophobic barrier that separates the cell from its environment.

Question 10

A mutation causes a substitution of a nonpolar amino acid for a polar amino acid in the active site of an enzyme. What is the most likely effect on enzyme function?

Accepted Answer

The enzyme's ability to bind its substrate may decrease due to altered active site polarity.

Question 11

Which of the following best explains why cellulose cannot be digested by humans?

Accepted Answer

Humans lack the enzyme to hydrolyze $$\beta-1$$,4 glycosidic bonds found in cellulose.

Question 12

Which of the following is a correct description of the central dogma of molecular biology?

Accepted Answer

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

Question 13

Which of the following best describes the function of regulatory enzymes in metabolic pathways?

Accepted Answer

They catalyze the rate-limiting step and are often subject to feedback inhibition.

Question 14

A patient presents with abnormally high blood triglyceride levels. Which metabolic process is most likely impaired?

Accepted Answer

Lipid metabolism (specifically, beta-oxidation)

Question 15

Which of the following is the correct complementary base pairing in DNA?

Accepted Answer

Adenine pairs with Thymine, and Guanine pairs with Cytosine.

Question 16

Which of the following best describes the structure of a nucleotide found in RNA?

Accepted Answer

A ribose sugar, a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, or uracil)

Question 17

A researcher is studying the effect of substrate concentration on enzyme activity. She observes that at high substrate concentrations, the reaction rate plateaus. What is the most likely explanation?

Accepted Answer

The enzyme is saturated with substrate and is operating at $$V_{max}.$$

Question 18

Which of the following is a correct statement about the amphipathic nature of phospholipids?

Accepted Answer

They contain both hydrophilic (polar) heads and hydrophobic (nonpolar) tails.

Question 19

Which of the following best explains why polysaccharides such as starch and glycogen are suitable for energy storage in animals and plants?

Accepted Answer

They are large, insoluble molecules that can be broken down into glucose when needed.

Question 20

A patient is found to have a mutation in the gene encoding for a regulatory enzyme in glycolysis. Which of the following is a likely consequence?

Accepted Answer

Disruption of glucose metabolism and possible accumulation of metabolic intermediates.

Biochemistry Course Schedule and Topic Overview

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