Question 1

Which property of carbon most directly contributes to its ability to form large, complex, and diverse molecules essential for life?

Accepted Answer

Its four valence electrons allow it to form up to four covalent bonds with other atoms.

Question 2

Which of the following best describes a dehydration reaction in the synthesis of biological polymers?

Accepted Answer

A water molecule is removed, forming a new covalent bond between monomers.

Question 3

Which functional group is present in all amino acids and acts as a base by accepting H+ ions?

Accepted Answer

Amino group ($$-NH_2$)

Question 4

A molecule with the formula $$C_6H_{12}O_6$ is classified as which type of carbohydrate?

Accepted Answer

Monosaccharide

Question 5

Which of the following statements about cellulose and starch is correct?

Accepted Answer

Starch has $$\alpha$$ glycosidic linkages, while cellulose has $$\beta$$ glycosidic linkages.

Question 6

Which of the following best explains why unsaturated fats are typically liquid at room temperature?

Accepted Answer

Their fatty acid chains contain double bonds, causing kinks that prevent tight packing.

Question 7

A phospholipid differs from a fat (triglyceride) in which of the following ways?

Accepted Answer

It contains a phosphate group and only two fatty acids attached to glycerol.

Question 8

Which of the following is a correct pairing of a nitrogenous base with its complement in DNA?

Accepted Answer

Adenine with thymine

Question 9

A single amino acid substitution in the primary structure of hemoglobin leads to sickle-cell disease. This is an example of how:

Accepted Answer

A change in primary structure can alter protein shape and function.

Question 10

Which of the following best describes the quaternary structure of a protein?

Accepted Answer

The association of two or more polypeptide chains into a functional protein.

Question 11

Which process is responsible for breaking down glycogen into glucose monomers in the human body?

Accepted Answer

Hydrolysis

Question 12

Which of the following is a real-world consequence of the inability of humans to hydrolyze $$\beta$$ linkages in cellulose?

Accepted Answer

Cellulose passes through the digestive tract as insoluble fiber.

Question 13

Which of the following best explains why cholesterol is considered both essential and potentially harmful in animals?

Accepted Answer

It is a component of cell membranes but can contribute to atherosclerosis at high levels.

Question 14

Which of the following statements about nucleic acids is correct?

Accepted Answer

DNA provides directions for its own replication and for protein synthesis.

Question 15

Which of the following best describes the backbone of a polynucleotide strand?

Accepted Answer

Alternating sugars and phosphate groups

Question 16

Which of the following is a direct result of denaturation in a protein?

Accepted Answer

The protein loses its three-dimensional structure and function.

Question 17

Which of the following is a correct statement about the difference between purines and pyrimidines?

Accepted Answer

Purines include adenine and guanine; pyrimidines include cytosine, thymine, and uracil.

Question 18

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

Accepted Answer

Their hydrophobic tails avoid water, while their hydrophilic heads interact with water.

Question 19

Which of the following is a real-life example of the importance of protein structure for biological function?

Accepted Answer

The ability of enzymes to catalyze specific reactions depends on their three-dimensional shape.

Chapter 3: Carbon and the Molecular Diversity of Life - Study Notes

Study Guide - Practice Questions