Question 1

Which enzyme is responsible for relieving the twisting stress that occurs ahead of the replication fork during DNA replication?

Accepted Answer

Topoisomerase

Question 2

During DNA replication, which strand is synthesized discontinuously, and what are the short fragments called?

Accepted Answer

Lagging strand; Okazaki fragments

Question 3

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 4

Which process allows bacteria to acquire antibiotic resistance genes from their environment without cell-to-cell contact?

Accepted Answer

Transformation

Question 5

What is the main function of single-strand binding proteins (SSBs) during DNA replication?

Accepted Answer

To keep the separated DNA strands stable and prevent re-annealing

Question 6

Which of the following best describes the role of integrons in bacterial evolution?

Accepted Answer

They are DNA elements that capture and express gene cassettes, often conferring multidrug resistance

Question 7

A bacterium is exposed to UV radiation, resulting in a thymine dimer. Which DNA repair mechanism is most likely to fix this damage?

Accepted Answer

Nucleotide excision repair

Question 8

Which of the following is a key difference between transcription in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes process mRNA with splicing, 5' cap, and poly-A tail before export from the nucleus

Question 9

Which of the following best explains why horizontal gene transfer is significant for bacterial evolution?

Accepted Answer

It enables bacteria to acquire new traits, such as antibiotic resistance, from unrelated organisms

Question 10

A scientist discovers a bacterial strain with a plasmid carrying a gene for a novel metabolic pathway. Which process most likely allowed this gene to spread rapidly among different bacterial species?

Accepted Answer

Conjugation

Question 11

Which of the following statements about transposons is correct?

Accepted Answer

They can carry antibiotic resistance genes and move within or between DNA molecules

Question 12

A patient is infected with a bacterial strain that produces a toxin encoded by a gene originally from a bacteriophage. What is this process called?

Accepted Answer

Lysogenic conversion

Question 13

Which of the following best describes the semiconservative nature of DNA replication?

Accepted Answer

Each new DNA molecule contains one parental and one newly synthesized strand

Question 14

Which of the following is a real-life consequence of protein misfolding in humans?

Accepted Answer

Diseases such as Alzheimer’s and Parkinson’s

Question 15

Which of the following best describes the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments on the lagging strand

Question 16

A bacterial cell is exposed to a chemical mutagen that causes the insertion of a single nucleotide into a gene. What is the most likely result?

Accepted Answer

Frameshift mutation

Question 17

Which of the following is NOT a function of molecular chaperones?

Accepted Answer

Degrading misfolded proteins

Question 18

Which of the following best describes the role of tRNA during translation?

Accepted Answer

It brings the correct amino acid to the ribosome by matching its anticodon to the mRNA codon

Question 19

Which of the following is a direct result of a point mutation that does NOT change the amino acid sequence of a protein?

Accepted Answer

Silent mutation

Question 20

Which of the following best explains why DNA repair is essential for bacterial survival?

Accepted Answer

It maintains genome stability and prevents accumulation of harmful mutations

Bacterial Gene Transfer, DNA Replication, and the Central Dogma

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