Question 1

Which of the following statements best explains why carbon is considered the backbone of organic molecules?

Accepted Answer

Carbon can form up to four strong covalent bonds, allowing for a diversity of stable molecular structures.

Question 2

Which chemical group is NOT found in all amino acids?

Accepted Answer

Phosphate group

Question 3

Which process is responsible for joining monomers to form polymers, and what is a byproduct of this reaction?

Accepted Answer

Dehydration synthesis; water is released

Question 4

Which of the following best describes the difference between glucose and fructose?

Accepted Answer

They have the same molecular formula but different structural arrangements, making them isomers.

Question 5

Which polysaccharide is used for energy storage in animals?

Accepted Answer

Glycogen

Question 6

Why can humans digest starch but not cellulose, even though both are polymers of glucose?

Accepted Answer

The glycosidic linkages in cellulose are different, and human enzymes cannot break them.

Question 7

Which of the following statements about lipids is FALSE?

Accepted Answer

Lipids are hydrophilic and dissolve easily in water.

Question 8

What is the main structural difference between saturated and unsaturated fatty acids?

Accepted Answer

Saturated fatty acids have only single C–C bonds, while unsaturated fatty acids have at least one double C=C bond.

Question 9

Why are trans fats considered more harmful than saturated fats?

Accepted Answer

Trans fats increase the risk of cardiovascular disease more than saturated fats.

Question 10

Which of the following foods is a good source of omega-3 fatty acids?

Accepted Answer

Salmon

Question 11

Which of the following is NOT a function of proteins in living organisms?

Accepted Answer

Storing genetic information

Question 12

A single amino acid substitution in the primary structure of hemoglobin can lead to which disease?

Accepted Answer

Sickle-cell disease

Question 13

Which level of protein structure is primarily determined by hydrogen bonds between the backbone atoms?

Accepted Answer

Secondary structure

Question 14

What happens to a protein when it is denatured?

Accepted Answer

Its three-dimensional structure is disrupted, and it loses its biological function.

Question 15

Which of the following best describes the structure of a nucleotide?

Accepted Answer

A phosphate group, a five-carbon sugar, and a nitrogenous base

Question 16

Which statement correctly compares DNA and RNA?

Accepted Answer

DNA contains deoxyribose and thymine, while RNA contains ribose and uracil.

Question 17

Which of the following foods would provide all essential amino acids for humans?

Accepted Answer

A meal containing both rice and beans

Question 18

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

Accepted Answer

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

Question 19

Which of the following is a function of cholesterol in animal cells?

Accepted Answer

It is a component of cell membranes and a precursor for steroid hormones.

Question 20

Which process breaks down polymers into monomers, and what is required for this reaction?

Accepted Answer

Hydrolysis; water is required

CH3 - Molecules

Study Guide - Practice Questions