Question

Which of the following is/are incorrect with regard to the nitrogenous bases of DNA?

• A. Adenine and Guanine are purines
• B. Uracil and Cytosine are pyrimidines
• C. Thymine and Cytosine are pyrimidines
• D. Adenine and Thymine are purines

Answer 1

Answer: (B), (D)

Adenine and Thymine are purines

Nitrogenous bases are broadly of two types - purines and pyrimidines. Adenine and guanine are the purines, while thymine and cytosine are the pyrimidines of DNA. In RNA, uracil replaces thymine, whereas all the other bases remain the same.