Question 2

Cytosine (C) and Thymine (T) are known as Pyrimidines.

Cytosine (C) and Thymine (T) are classified as pyrimidines, which are one of the two categories of nitrogenous bases found in nucleic acids. Pyrimidines are characterized by their single-ring structure, distinguishing them from purines, which have a double-ring structure.

A) Purines

Purines, which include adenine (A) and guanine (G), are defined by their double-ring structure. Since Cytosine (C) and Thymine (T) do not fit this structural characteristic, this option is incorrect.

B) Pyrimidines

Cytosine (C) and Thymine (T) are indeed pyrimidines, making this option correct. Pyrimidines are essential components of DNA and RNA, and their single-ring structure is a key feature distinguishing them from purines.

C) Both

This option suggests that both purines and pyrimidines include Cytosine (C) and Thymine (T), which is misleading. Since both bases are specifically classified as pyrimidines, this option is incorrect.

D) None of the above

This choice states that Cytosine (C) and Thymine (T) do not belong to any of the categories mentioned, which is false. As established, both are classified as pyrimidines, making this option incorrect.

Conclusion

Cytosine (C) and Thymine (T) are accurately categorized as pyrimidines due to their structural characteristics. All other options fail to correctly classify these bases, with purines being a completely different category. Thus, option B is the only correct answer.