Question

which statement is true about the nitrogen bases in dna and rna?
a uracil is found in rna only. guanine is found in dna only
b uracil is found in rna only. thymine is found in dna only
c adenine is found in rna only. thymine is found in dna only
d thymine is found in rna only. uracil is found in dna only

Explanation:

To determine the correct statement, recall the nitrogen bases in DNA and RNA: DNA has adenine (A), thymine (T), cytosine (C), guanine (G). RNA has adenine (A), uracil (U), cytosine (C), guanine (G). So uracil is RNA - only, thymine is DNA - only. Option a: Guanine is in both, so wrong. Option c: Adenine is in both, wrong. Option d: Thymine is DNA - only, Uracil is RNA - only (this option has them reversed), wrong. Option b: Uracil (RNA only) and Thymine (DNA only) is correct.

Answer:

b. Uracil is found in RNA only. Thymine is found in DNA only.