Structures of the nucleic acid bases

This type of question, asked 3 times: 2021 Paper 20, 6 Apr 2024, 24 Jan 2025. All 3 questions below, oldest first.

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Question 1
2021 Paper 20
45 $Out of following isomeric forms of uracil, which one is present in RNA?$
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Question 2
6 Apr 2024
35 $DNA molecule contains 4 bases whose structures are shown below. One of the structures is not correct, identify the incorrect base structure.$
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Question 3
24 Jan 2025
119 $Match List-I with List-II. List-I List-II (A) Adenine (I) (B) Cytosine (II) (C) Thymine (III) (D) Uracil (IV) Choose the correct answer from the options given below :$
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Question 1