This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemistry of Nucleotides , Subject name: Biochemistry
In DNA, Cytosine is paired with - 
Select and explain. 
A. Thymine, B. Guanine, C. Ademine, D. Uracil
B: Guanine
Answer: B: Guanine 
Explanation: Ans. is 'b' i.e., Guanine o The sugar of DNA is deoxyribose. The purine bases in DNA are adenine (A) and Guanine (G) Q, and pyrimidine bases are thymine (T) and cytosine (C) Q. Uracil (U), a pyrimidine, is not found in DNAQ.o Adenine is always paired with thymine by formation of two hydrogen bonds and Guanine is always paired with cytosine by formation of three hydrogen bonds.Antiparallel strands of DNA