Question

Nitrogenous base not present in RNA is
a. Uracil
b. Thymine
c. Guanine
d. Cytosine

Answer 1

Hint: Nucleic acids include both deoxyribonucleic acids and ribonucleic acids, which contain nucleotides, these nucleotides are the building blocks of this nucleic acids, and this nucleotide are again of two types, they are purines and pyrimidines.

Complete answer:
- RNA has nucleotides, and they play an important role as a messenger, where the genetic information from the DNA to the protein synthesis components is called ribosomes.
- Generally, RNA is very similar to DNA, except for some structural changes, in which DNA is a double-strand nucleic acid, whereas RNA is a single strand.
- RNA contains ribose sugars, whereas DNA contains deoxyribose sugars.
- RNA is transcribed from the DNA, by the enzyme RNA polymerase, and RNA is formed, and after that RNA is processed.
- This ribonucleic acid acts as a template for the synthesis of proteins, where it transforms the genetic material from the genes to protein synthesis components, to form the amino acids.
- DNA is deoxyribonucleic acid, with a phosphate bone, where it consists of nucleotides such as adenine, thymine, cytosine, guanine.
- Whereas in the RNA, it consists of Ribonucleic acid and phosphate backbone, and nucleotides are similar to that of DNA, except for Thymine wherein the RNA is replaced by the uracil.
- Thymine is replaced by the uracil which is complementary to adenine.

Hence, the correct answer is option (B).

Note: The function of uracil and the thymine are the same, the production of uracil is energetically more feasible, where an additional methyl group is added in order to convert the thymine to the uracil.