Which statement is true about a triplet code?

• A. A triplet code uses four nucleobases.
• B. Each triplet encodes multiple amino acids.
• C. A triplet code consists of three nucleobases.
• D. Triplet codes are not used in biology.

Answer: (C)

A triplet code is read in groups of three nucleotides, forming codons. Each codon specifies a single amino acid (or a stop signal) during protein synthesis. With four nucleobases available, three-position codons create 4 × 4 × 4 = 64 possible codons, which is enough to encode the 20 amino acids plus the stop signals.

The statement that a triplet code uses four nucleobases would be misleading because the important point is that the codon length is three, even though the genetic alphabet has four bases. The idea that a single triplet encodes multiple amino acids is incorrect because one codon maps to one amino acid (or a stop). And triplet codes are indeed used in biology. So the true statement is that a triplet code consists of three nucleobases.