Question

which of the following statements describes proteins? a only proteins are comprised of repeating units of cytosine, adenine, guanine, and thymine. b only proteins are formed from amino acids joined by peptide bonds. c only proteins provide short bursts of energy. d only proteins can be large molecules with thousands of subunits.

Explanation:

A: Cytosine, adenine, guanine, thymine are nucleotides (DNA/RNA), not protein subunits.
B: Proteins are uniquely amino acids linked by peptide bonds.
C: Short energy bursts come from carbohydrates, not proteins.
D: Large molecules with many subunits include DNA/polysaccharides, not only proteins.

Answer:

B. Only proteins are formed from amino acids joined by peptide bonds.