本题目来源于试卷: Unity and Diversity A.2 Nucleic Acids，类别为 IB生物学
[单选题]
What distinguishes urg0r j gjm25o+4a ukx/qacil f mq8xjlhx4jk,8.h 8 zlrom thymine?
A. Uracil is Joined to a pentose sugar;Thymine is Joined to a hexose sugar
B. Uracil is Found in RNA;Thymine is Found in DNA
C. Uracil is Two-ring structure;Thymine is Single-ring structure
D. Uracil is Complementary to cytosine;Thymine is Complementary to adenine
参考答案: B
本题详细解析:
Uracil and thymine are nitrogenous bases found in s(/8otc r 2toftwo types of nucleic acids: DNA and RNA.Uracil is found in RNA, whereas thymine is found in DNA. (Choice B)Uracil pairs with adenine in RNA and thymine pairs with adenine in DNA (Choice D).In b (s8ttorcf2o/oth DNA and RNA, these nitrogenous bases are joined to a five-carbon sugar, also called a pentose sugar which has a ring structure, so Choice A is incorrect.Both uracil and thymine are pyrimidines which are single-ring structures (Choice C). Adenine and guanine are purines which consist of two rings.
| 
