HINT: RNA does not contain thymine.

Explanation:

Ribonucleic acid is a polymeric molecule essential in various biological roles in coding, decoding, regulation, and expression of genes. RNA and deoxyribonucleic acid are nucleic acids.

DNA contains four bases adenine, guanine, thymine, and cytosine. While RNA contains four bases adenine, uracil, guanine, and cytosine. Thus, RNA does not contain thymine.


The chemical structure consists of an aminopyrimidine and a thiazolium ring linked by a methylene bridge

Hence, statement (3) is the correct choice.
 

• RNA is a single-stranded helix.
• The strand has a 5′end (with a phosphate group) and a 3′end (with a hydroxyl group).
• It is composed of ribonucleotides.
• The ribonucleotides are linked together by 3′ –> 5′ phosphodiester bonds.
• The nitrogenous bases that compose the ribonucleotides include adenine, cytosine, uracil, and guanine.

Thus, the difference in the structure of RNA from that of DNA include:

• The bases in RNA are adenine (abbreviated A), guanine (G), uracil (U) andcytosine (C).