Read the passage carefully and answer the questions:
Optically active polyhydroxy aldehydes or ketones or molecules which provide such units on hydrolysis are called carbohydrates. They can be broadly classified as monosaccharides, disaccharides and polysaccharides depending on their behavior towards hydrolysis. They are also classified as reducing or non reducing sugars. Another class of biomolecules is proteins which are polymers of twenty different amino acids linked by peptide bonds. Amino acids can be classified as acidic, basic or neutral depending on the relative number of amino and carboxyl groups in their molecule. The essential amino acids cannot be synthesized by our body and hence must be provided through diet. Nucleic acids are the polymers of nucleotides which in turn consist of a base, pentose sugar and phosphate. There are two types of nucleic acids namely, DNA and RNA which differ in the composition of sugar and a base.
Four bases present in RNA molecule are
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Adenine, Guanine, Cytosine, Uracil
Nucleic acids carry two kinds of bases. The purines adenine (A) and guanine (G) are found in both DNA and RNA, and so is the pyrimidine cytosine (C). The fourth base differs: DNA has thymine (T), while RNA has uracil (U) in its place.
\( \displaystyle \text{DNA: A, G, C, T} \qquad \text{RNA: A, G, C, U} \)
So the four bases of RNA are adenine, guanine, cytosine and uracil.
NCERT (2026-27 edition):
Chemical Composition of Nucleic Acids – …
