Nucleic Acids – Chemical Constitution of DNA and RNA, Biological Functions NEET Questions

Organic Chemistry - Biomolecules

Nucleic Acids – Chemical Constitution of DNA and RNA, Biological Functions MCQ Questions


7.
Adenine differs from guanine in that:
A.
Adenine has an amino group at C-6, while guanine has C=O at C-6 and -NH2 at C-2
B.
Adenine is a pyrimidine, guanine is a purine
C.
Adenine has 5 nitrogens, guanine has 3
D.
Adenine pairs with cytosine, guanine pairs with thymine
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ANSWER :
A. Adenine has an amino group at C-6, while guanine has C=O at C-6 and -NH2 at C-2
8.
Cytosine has which functional groups on its pyrimidine ring?
A.
Two -NH2 groups
B.
Two C=O groups
C.
An -NH2 group at C-4 and C=O at C-2
D.
An -NH2 at C-6 only
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ANSWER :
C. An -NH2 group at C-4 and C=O at C-2
9.
The structural difference between thymine and uracil is:
A.
Different ring sizes
B.
Thymine has more nitrogen atoms
C.
Thymine is a purine, uracil is a pyrimidine
D.
Thymine has -CH3 at C-5; Uracil has -H at C-5
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ANSWER :
D. Thymine has -CH3 at C-5; Uracil has -H at C-5
10.
When adenine is attached to 2-deoxyribose, the resulting nucleoside is called:
A.
Adenosine
B.
Deoxyadenosine
C.
Adenylic acid
D.
Adenine triphosphate
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ANSWER :
B. Deoxyadenosine
11.
Match: When cytosine attaches to ribose, the nucleoside is:
A.
Deoxycytidine
B.
Cytidine
C.
Cytosylribose
D.
Cytidylic acid
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ANSWER :
B. Cytidine
12.
The bond between the base and sugar in a nucleoside is:
A.
Ionic bond
B.
C-S bond
C.
C=C double bond
D.
C-N bond (β-glycosidic linkage)
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ANSWER :
D. C-N bond (β-glycosidic linkage)