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 uracil from thym:/p44d.2z du0t dj)zxvixa eeip1et-i 3 fx7phg,r 7mtne?
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 araoy g+f3f;cn5e nitrogenous bases found in two types of nucleic acids: DNA and RNA.Uracil is found in RNA, whereas th;5n fay 3o+cgfymine 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 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.
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