Question

the structure of rna differs from dna in that
dna contains purines but not pyrimidines.
dna contains pyrimidines but not purines.
the backbone of rna contains ribose.
rna contains purines but not pyrimidines.
rna contains pyrimidines but not purines.

Explanation:

DNA contains both purines (adenine and guanine) and pyrimidines (cytosine and thymine). RNA contains both purines (adenine and guanine) and pyrimidines (cytosine and uracil). The key structural difference is that the backbone of RNA contains ribose sugar while DNA has deoxy - ribose sugar.

Answer:

the backbone of RNA contains ribose.