Question

Which of the following elements is not present in a nitrogenous base?

• A. Hydrogen
• B. Carbon
• C. Phosphorus
• D. Nitrogen

Answer 1

The correct option is C Phosphorus

The nitrogen base present in nucleic acids has nitrogen, carbon, hydrogen and oxygen in the ring structure. Two types of nitrogen bases occur. They are-

1) Purines which have a double ring structure. They are adenine and guanine.

2) Pyrimidines, which have a single ring structure. They are thymine, cytosine and uracil.

Phosphorus forms a part of the nucleotides in the nucleic acid but it is not a part of the nitrogenous base. Thus the correct answer is option C.