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 uld+nyg d61r :cracilblwe ftx5irn z ;4));vx+isu5 9z2 hrn from 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 ia dnql ,4m;7 5mpgzff3n two 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 both DNA and RNA, these nitrogenous bases are joined to a fmz7mp 34 q,fa5; fgndlive-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.
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