LIFE SCIENCE

Detailed explanation-1: -DNA and RNA base pairing is slightly different since DNA uses the bases adenine, thymine, cytosine, and guanine; RNA uses adenine, uracil, cytosine, and guanine. Uracil differs from thymine in that it lacks a methyl group on its ring.

Detailed explanation-2: -There are two differences that distinguish DNA from RNA: (a) RNA contains the sugar ribose, while DNA contains the slightly different sugar deoxyribose (a type of ribose that lacks one oxygen atom), and (b) RNA has the nucleobase uracil while DNA contains thymine.

Detailed explanation-3: -Uracil (U) is one of the four nucleotide bases in RNA, with the other three being adenine (A), cytosine (C) and guanine (G). In RNA, uracil pairs with adenine. In a DNA molecule, the nucleotide thymine (T) is used in place of uracil.

Detailed explanation-4: -Answer and Explanation: RNA uses uracil instead of thymine because RNA is already short-lived (compared to DNA) and errors don’t lead to long-lasting damage. Most importantly, uracil is less stable than thymine thereby making it easier to break down, as it is essentially a demethylated version of thymine.