Question 1

Which of the following statements best explains why carbon is considered the most versatile building block of biological molecules?

Accepted Answer

Carbon can form up to four covalent bonds, allowing it to create a wide variety of complex structures.

Question 2

A scientist is studying a molecule with the following structure: a carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group. Which functional group is present?

Accepted Answer

Carboxyl group ($-COOH$)

Question 3

Which functional group is responsible for making molecules more hydrophobic and is non-polar?

Accepted Answer

Methyl group ($-CH_3$)

Question 4

During the formation of a peptide bond between two amino acids, which type of reaction occurs and what is released?

Accepted Answer

Dehydration synthesis; water ($H_2O$) is released

Question 5

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

Accepted Answer

Regular coiling and folding of the polypeptide backbone stabilized by hydrogen bonds

Question 6

A mutation causes a change in the primary structure of a protein. Which of the following levels of protein structure will be directly affected as a result?

Accepted Answer

All subsequent levels: secondary, tertiary, and quaternary structures

Question 7

Which of the following statements about cellulose is correct?

Accepted Answer

Cellulose is a structural polysaccharide composed of unbranched glucose polymers and cannot be digested by most animals.

Question 8

Which functional group is most likely to act as a base and is found in amino acids?

Accepted Answer

Amino group ($-NH_2$)

Question 9

A triglyceride is formed by the joining of three fatty acids to a glycerol molecule. What type of bond is formed during this process, and what is the reaction called?

Accepted Answer

Ester bond; dehydration synthesis

Question 10

Which of the following best explains why phospholipids are essential for cell membrane structure?

Accepted Answer

They have both hydrophilic and hydrophobic regions, allowing them to form bilayers in aqueous environments.

Question 11

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

Accepted Answer

Protein – Amino acid

Question 12

A patient is unable to digest milk sugar (lactose). Which type of bond is the patient unable to hydrolyze?

Accepted Answer

Glycosidic bond

Question 13

Which of the following best describes the role of the phosphate group in nucleic acids?

Accepted Answer

It links nucleotides together via phosphodiester bonds and is important in energy transfer.

Question 14

Which of the following is a correct statement about the hydrolysis of polymers?

Accepted Answer

Hydrolysis breaks covalent bonds between monomers by the addition of water.

Question 15

A protein is exposed to high heat and loses its three-dimensional structure but retains its primary sequence. What process has occurred?

Accepted Answer

Denaturation

Question 16

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

Accepted Answer

The arrangement and interaction of multiple polypeptide subunits in a single protein

Question 17

Which of the following functional groups is critical for stabilizing protein structure through the formation of disulfide bridges?

Accepted Answer

Sulfhydryl group ($-SH$)

Question 18

Which of the following is a structural polysaccharide found in the exoskeleton of arthropods and the cell walls of fungi?

Accepted Answer

Chitin

Question 19

A molecule contains a phosphate group, a pentose sugar, and a nitrogenous base. This molecule is most likely a:

Accepted Answer

Nucleotide

Question 20

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

Accepted Answer

They lack the enzyme required to hydrolyze the specific glycosidic linkages in cellulose.

Biological Molecules: Structure, Function, and Classification

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