Question 1

Which of the following statements best explains why humans cannot digest cellulose, even though it is a polymer of glucose?

Accepted Answer

Cellulose contains beta (β) linkages between glucose units, and humans lack the enzymes to hydrolyze these bonds.

Question 2

A patient is diagnosed with lactose intolerance. Which enzyme is deficient, and what is the consequence for carbohydrate digestion?

Accepted Answer

Lactase is deficient, so lactose cannot be hydrolyzed into glucose and galactose.

Question 3

Which of the following best describes the difference between amylose and amylopectin?

Accepted Answer

Amylose is a linear polymer of glucose, while amylopectin is a branched polymer of glucose.

Question 4

Which of the following equations correctly represents the photosynthesis reaction in plants?

Accepted Answer

$$6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\ \mathrm{O}_2$$

Question 5

Which of the following statements about lipids is correct?

Accepted Answer

Lipids are biological molecules that are insoluble in water but soluble in nonpolar organic solvents.

Question 6

A triglyceride is formed by the reaction of which two types of molecules?

Accepted Answer

Glycerol and three fatty acids

Question 7

Which type of lipoprotein is considered 'bad cholesterol' and why?

Accepted Answer

Low-density lipoprotein (LDL) because it carries cholesterol from the liver to the blood, contributing to plaque formation.

Question 8

Which of the following best describes a zwitterion?

Accepted Answer

A molecule with both a positive and a negative charge, but overall neutral, such as an amino acid at physiological pH.

Question 9

Which of the following bonds is responsible for the primary structure of proteins?

Accepted Answer

Peptide (amide) bonds between amino acids

Question 10

A mutation changes the sequence of amino acids in a protein. Which level of protein structure is directly affected first?

Accepted Answer

Primary structure

Question 11

Which of the following is a correct description of the induced-fit model of enzyme action?

Accepted Answer

The enzyme changes shape to fit the substrate upon binding, forming an enzyme–substrate complex.

Question 12

Which of the following is a coenzyme?

Accepted Answer

A nonprotein organic molecule required for enzyme function

Question 13

Which of the following best explains why trans fats are considered unhealthy?

Accepted Answer

Trans fats increase LDL cholesterol levels, which can lead to plaque formation in arteries.

Question 14

Which of the following statements about DNA and RNA is correct?

Accepted Answer

DNA is double-stranded and contains thymine, while RNA is single-stranded and contains uracil.

Question 15

During protein synthesis, what is the role of messenger RNA (mRNA)?

Accepted Answer

It carries the genetic code from DNA to the ribosome for translation.

Question 16

Which of the following best describes the process of gene therapy?

Accepted Answer

Introducing a functioning gene into a person’s cells to correct a defective gene

Question 17

Which of the following is a real-world application of enzymes in medicine?

Accepted Answer

Enzymes are used to break up blood clots after a heart attack.

Question 18

Which of the following best describes the role of hydrogen bonds in the structure of DNA?

Accepted Answer

Hydrogen bonds hold complementary base pairs together in the double helix.

Question 19

Which of the following best explains why proteins tend to have nonpolar groups on the inside and polar groups on the outside?

Accepted Answer

Nonpolar groups are hydrophobic and avoid water, while polar groups are hydrophilic and interact with water.

Biochemistry: The Chemistry of Life – Study Notes for Introductory Chemistry

Study Guide - Practice Questions