Final answer:
Adenine and guanine are purines with a two-ringed base; uracil is a pyrimidine with a one-ringed base; and thymine, also a pyrimidine, is unique to DNA.
Step-by-step explanation:
The statements which are true about purines and pyrimidines are:
- C) PURINES HAVE TWO-RINGED BASE - Purines, which include adenine (A) and guanine (G), have a double-ring structure.
- E) Adenine is a purine - Adenine, along with guanine, is classified as a purine due to its double-ring structure.
- G) Uracil is a pyrimidine - Uracil, found only in RNA, is a pyrimidine because it has a single-ring structure.
- H) pyrimidine has a one-ringed base - Pyrimidines, which include cytosine (C), thymine (T), and uracil (U), have a single-ring structure.
Contrary to some of the other options listed, purines have a two-ringed base, not one, and guanine is a purine, not a pyrimidine. Thymine and adenine cannot both be purines since thymine is actually a pyrimidine. Pyrimidines consist of a single-ringed base, not two.