Question 1

Which of the following statements best explains why carbon is the backbone of biological macromolecules?

Accepted Answer

Carbon can form up to four covalent bonds due to its four valence electrons, enabling the construction of large, complex, and varied molecules.

Question 2

Which of the following is NOT a characteristic of a hydrocarbon?

Accepted Answer

Readily dissolves in water due to its polar nature.

Question 3

A molecule with the formula $$C_6H_{12}O_6$ can exist as different isomers. Which type of isomerism is responsible for glucose and fructose having the same formula but different structures?

Accepted Answer

Structural isomerism

Question 4

Which functional group is most likely to confer a negative charge to a molecule and enable it to participate in energy transfer reactions such as those involving ATP?

Accepted Answer

Phosphate group ($$-$$OPO_3$$^{2-})$$

Question 5

Which process is responsible for breaking down a polymer into its monomers by adding a molecule of water?

Accepted Answer

Hydrolysis

Question 6

Which of the following best describes the difference between starch and cellulose?

Accepted Answer

Starch has branched chains, while cellulose is always a straight, unbranched polymer.

Question 7

Which of the following statements about phospholipids is correct?

Accepted Answer

They spontaneously form bilayers in aqueous environments due to their hydrophilic heads and hydrophobic tails.

Question 8

A patient is diagnosed with sickle-cell disease, which is caused by a single amino acid substitution in the hemoglobin protein. This is an example of how:

Accepted Answer

A change in the primary structure of a protein can alter its function.

Question 9

Which of the following best explains why unsaturated fats are liquid at room temperature while saturated fats are solid?

Accepted Answer

Unsaturated fats have double bonds that create kinks, preventing tight packing of molecules.

Question 10

Which of the following is a correct pairing of a macromolecule and its monomer?

Accepted Answer

Carbohydrate – Monosaccharide

Question 11

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

Enzymes speed up dehydration and hydrolysis reactions without being consumed.

Question 12

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

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Question 13

A dehydration reaction is used to join two glucose molecules. What is the resulting molecule and what type of bond is formed?

Accepted Answer

A disaccharide is formed with a glycosidic linkage.

Question 14

Which of the following best explains why only one enantiomer of a drug may be biologically active?

Accepted Answer

Only one enantiomer can bind to specific molecules in an organism due to its unique spatial configuration.

Question 15

Which of the following is a function of cholesterol in animal cell membranes?

Accepted Answer

It maintains membrane fluidity and serves as a precursor for steroid hormones.

Question 16

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 17

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

Accepted Answer

$$DNA \rightarrow RNA \rightarrow Protein$$

Question 18

Which of the following best explains why humans cannot digest cellulose?

Accepted Answer

Humans lack the enzymes to hydrolyze the specific glycosidic linkages in cellulose.

Question 19

Which of the following is a correct pairing of a functional group and its property?

Accepted Answer

Phosphate group ($$-$$OPO_3$$^{2-}$$): contributes negative charge

Carbon and the Molecular Diversity of Life: Structure and Function of Biomolecules

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