Identify the nitrogen base which is not a part of DNA?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Uracil
The bases of nucleic acids are purines (adenine, guanine) and pyrimidines (cytosine, thymine, uracil).
Option (1) Uracil — Not a part of DNA. Uracil is found in RNA, in place of thymine.
Option (2) Adenine — A part of DNA. A purine present in both DNA and RNA.
Option (3) Guanine — A part of DNA. A purine present in both DNA and RNA.
Option (4) Cytosine — A part of DNA. A pyrimidine present in both DNA and RNA.
NCERT (2026-27 edition):
Chemical Composition of Nucleic Acids – …
