Question

Witch of the following is not a purine ?

Guanine
Cytosine
Thymine
none of the above

Answer 1

Cytosine and thymine

Step-by-step explanation:

Purines- Adenine, guanine

Pyrimidines- cyosine, thymine, uracil (in RNA)

Answer 2

Cytosine and thymine.

Step-by-step explanation:

DNA is present as genetic material in all the living organism except some viruses. The structure of DNA contains a nitrogenous base, a pentose deoxyribose sugar and a phosphate group.

The nitrogenous base of DNA are characterized into purines and pyrimidines. The pyrimidines are six member ring and contains thymine and cytosine. Purines are nine member rings and contain adenine and guanine.

Thus, the correct answer is option (2) and (3).