Question

Statement 1: The four nitrogen bases in a DNA molecule are guanine, thymine adenine, cytosine.

Statement 2: Where adenine and thymine are purines and guanine and cytosine are pyrimidines.

• A. Statement 1 is true and statement 2 is false
• B. Statement 1 is false and statement 2 is true
• C. Both the statements are false
• D. Both the statements are true

Answer 1

The correct option is A

Statement 1 is true and statement 2 is false

Nitrogenous bases make up the building blocks of DNA and RNA. Adenine, guanine, cytosine and thymine are the nitrogenous bases of DNA whereas, in an RNA molecule, thymine is replaced by uracil. Purines and Pyrimidines are nitrogenous bases that make up the two different kinds of nucleotide bases in DNA and RNA. The two-carbon nitrogen ring bases adenine and guanine are purines, whereas the one-carbon nitrogen ring bases thymine and cytosine are pyrimidines. Hence statement 2 is false.