Question 1

Which property of carbon allows it to form a wide variety of complex organic molecules essential for life?

Accepted Answer

Carbon can form four covalent bonds due to its tetravalence.

Question 2

A molecule of methane ($$CH_4) $$has a tetrahedral shape. What is the reason for this molecular geometry?

Accepted Answer

The four pairs of bonding electrons around carbon repel each other equally, resulting in a tetrahedral geometry.

Question 3

Which functional group is responsible for the acidic properties of acetic acid, and what is its general structure?

Accepted Answer

Carboxyl group; $$-COOH$$

Question 4

Which of the following best describes the difference between structural isomers and enantiomers?

Accepted Answer

Structural isomers have different covalent arrangements of atoms; enantiomers are mirror images of each other.

Question 5

A pharmaceutical company finds that only one enantiomer of a drug is effective. What does this demonstrate about biological systems?

Accepted Answer

Biological systems are sensitive to even subtle variations in molecular structure.

Question 6

Which functional group is found in both estradiol and testosterone, and how does its presence affect the molecules?

Accepted Answer

Hydroxyl group ($$-OH$$); increases solubility and allows hydrogen bonding.

Question 7

Which of the following statements about ATP is correct?

Accepted Answer

ATP releases energy when it reacts with water, breaking a phosphate bond.

Question 8

Which of the following is NOT a polymer?

Accepted Answer

Lipid

Question 9

What type of reaction joins two monosaccharides to form a disaccharide, and what is the byproduct?

Accepted Answer

Dehydration reaction; water is released

Question 10

Which structural feature distinguishes saturated from unsaturated fatty acids?

Accepted Answer

Saturated fatty acids have only single bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.

Question 11

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

Accepted Answer

Humans lack enzymes to hydrolyze the $$\beta$$ glycosidic linkages in cellulose.

Question 12

Which level of protein structure is directly determined by the sequence of amino acids?

Accepted Answer

Primary structure

Question 13

A change in the primary structure of hemoglobin can lead to sickle-cell disease. What is the molecular consequence of this change?

Accepted Answer

The altered hemoglobin molecules aggregate and deform red blood cells.

Question 14

Which of the following pairs is correctly matched?

Accepted Answer

Pyrimidine: thymine

Question 15

What is the difference between a nucleotide and a nucleoside?

Accepted Answer

A nucleotide contains a nitrogenous base, a sugar, and a phosphate group; a nucleoside contains only a nitrogenous base and a sugar.

Question 16

Which of the following best describes the antiparallel arrangement of DNA?

Accepted Answer

The two strands run in opposite directions (one 5' to 3', the other 3' to 5').

Question 17

Which functional group is most likely to be found in a molecule that acts as a base in living organisms?

Accepted Answer

Amino group ($$-NH_2$)

Question 18

Which process is responsible for breaking down polymers into monomers in the digestive system?

Accepted Answer

Hydrolysis

Question 19

Which of the following is a real-world example of a molecule with a sulfhydryl group, and what is its biological significance?

Accepted Answer

Cysteine; forms disulfide bridges that stabilize protein structure

Carbon and the Molecular Diversity of Life & Structure and Function of Large Biological Molecules

Study Guide - Practice Questions