Structure of DNA and RNA
Q. In DNA, adenine pairs with which base?
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A.
Cytosine
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B.
Thymine
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C.
Guanine
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D.
Uracil
Solution
In DNA, adenine pairs with thymine through two hydrogen bonds.
Correct Answer: B — Thymine
Q. What is the basic structural unit of DNA?
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A.
Nucleotide
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B.
Amino acid
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C.
Monosaccharide
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D.
Fatty acid
Solution
DNA is composed of nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base.
Correct Answer: A — Nucleotide
Q. What is the role of mRNA in gene expression?
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A.
To replicate DNA
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B.
To transport amino acids
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C.
To carry genetic information from DNA to ribosomes
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D.
To form the ribosome structure
Solution
mRNA carries the genetic information from DNA to the ribosomes for protein synthesis.
Correct Answer: C — To carry genetic information from DNA to ribosomes
Q. What type of bond holds the two strands of DNA together?
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A.
Ionic bonds
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B.
Covalent bonds
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C.
Hydrogen bonds
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D.
Peptide bonds
Solution
Hydrogen bonds between complementary nitrogenous bases hold the two strands of DNA together.
Correct Answer: C — Hydrogen bonds
Q. Which of the following bases is found in RNA but not in DNA?
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A.
Thymine
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B.
Uracil
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C.
Cytosine
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D.
Adenine
Solution
RNA contains uracil instead of thymine, which is found in DNA.
Correct Answer: B — Uracil
Q. Which of the following is a characteristic of RNA?
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A.
Double-stranded structure
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B.
Contains deoxyribose
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C.
Single-stranded structure
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D.
Contains thymine
Solution
RNA is typically single-stranded and contains ribose sugar.
Correct Answer: C — Single-stranded structure
Q. Which process involves the synthesis of RNA from a DNA template?
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A.
Translation
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B.
Replication
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C.
Transcription
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D.
Mutation
Solution
Transcription is the process of synthesizing RNA from a DNA template.
Correct Answer: C — Transcription
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