Question

Hydrogen bonds present between cytosin and guanosine are

• A. $2$
• B. $3$
• C. $1$
• D. $4$

Answer 1

The correct option is B $3$

The nitrogenous bases present in the DNA are purines and pyrimidines. Purines are double ring while pyrimidines are single ring structure. Adenine and guanine are purines while thymine and cytosine are pyrimidines. A purine is attached to pyrimidine by hydrogen bond. Adenine is attached to thymine by two hydrogen bonds while three hydrogen bond is present between guanine and cytosine.

So, the correct answer is option B.