Chapter 4 MCQs

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. In terms of DNA and RNA structure, what is a nucleotide?

A nucleotide is a heterocyclic base. correct incorrect

A nucleotide is a sugar molecule covalently bonded to a heterocyclic base. correct incorrect

A nucleotide is a sugar molecule covalently bonded to phosphate groups and a heterocyclic base. correct incorrect

A nucleotide is a heterocyclic base covalently bonded to phosphate groups. correct incorrect

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. DNA exists as a double-stranded form, whereas RNA is mainly a single-stranded molecule. What is the likely reason for DNA being double-stranded?

RNA strands cannot form base pairs. correct incorrect

Double-stranded DNA is a more stable structure. correct incorrect

DNA cannot exist in the single-stranded form. correct incorrect

It is easier to replicate double-stranded DNA than single-stranded RNA. correct incorrect

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. How many stop codons are there in the genetic code?

1 correct incorrect

2 correct incorrect

3 correct incorrect

4 correct incorrect

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. Which of the following statements is true about DNA polymerase?

DNA polymerase can synthesise mRNA in the 3' to 5' direction. correct incorrect

DNA polymerase can synthesise DNA in the 5' to 3' direction. correct incorrect

DNA polymerase can synthesise mRNA in the 5' to 3' direction. correct incorrect

DNA polymerase can synthesise DNA in the 3' to 5' direction. correct incorrect

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. What is the role of topoisomerases in eukaryotic DNA replication?

Topoisomerase enzymes cut, uncoil and reseal the double-stranded DNA. correct incorrect

Topoisomerase enzymes join the Okazaki fragments together with phosphodiester bonds. correct incorrect

Topoisomerase enzymes open up the double-stranded DNA of the replication fork. correct incorrect

Topoisomerase enzymes bind to the origin of replication sites within double-stranded DNA. correct incorrect

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. Macrolide antibiotics inhibit transpeptidation by

binding to the 30s subunit of bacterial ribosomes. correct incorrect

binding to the 40s subunit of bacterial ribosomes. correct incorrect

binding to the 50s subunit of bacterial ribosomes. correct incorrect

binding to the 60s subunit of bacterial ribosomes. correct incorrect

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. Aminoglycoside antibiotics interfere with bacterial protein synthesis by

binding to the 30s subunit of bacterial ribosomes. correct incorrect

binding to the 40s subunit of bacterial ribosomes. correct incorrect

binding to the 50s subunit of bacterial ribosomes. correct incorrect

binding to the 60s subunit of bacterial ribosomes. correct incorrect

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. Which of the following drugs is NOT an anti-metabolite?

Methotrexate correct incorrect

Mercaptopurine correct incorrect

Fluorouracil correct incorrect

Chloramphenicol correct incorrect

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. Which of the following drugs is NOT an alkylating agent?

Chlorambucil correct incorrect

Doxorubicin correct incorrect

Cyclophosphamide correct incorrect

Busulphan correct incorrect

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. Which of the following drugs does NOT inhibit DNA polymerase?

Aciclovir correct incorrect

Idoxuridine correct incorrect

Vidarabine correct incorrect

Zidovudine correct incorrect