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 frnqtn+2nmr)je(,gjy a034(hsgth k6oomwi9jof 82l dy1ut56qa 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 niq5wgo nv +6f;vtrogenous bases found in two types of nucleic acids: DNA and RNA.Uracf 6vv5;owg nq+il 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 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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