$$\text{Mutation rate} = \frac{3}{1000}$$

Question 1

Which of the following best describes the genetic material found in a typical bacterium as shown in the first image?

Accepted Answer

A single circular chromosome and several plasmids

Question 2

What is the primary mechanism by which all mutations in prokaryotes are passed to the next generation?

Accepted Answer

Binary fission

Question 3

Which process is illustrated when a bacteriophage integrates its DNA into the bacterial chromosome, as shown in the second image?

Accepted Answer

Lysogeny

Question 4

Which of the following is a likely consequence of a frameshift mutation caused by an intercalating agent?

Accepted Answer

Alteration of the reading frame, resulting in a completely different amino acid sequence downstream

Question 5

A mutation that does not change the amino acid sequence of a protein is called:

Accepted Answer

Silent mutation

Question 6

Which of the following best explains why cancer drugs like BrdU cause side effects such as hair loss and nausea?

Accepted Answer

They target all rapidly dividing cells, not just cancer cells

Question 7

Which type of horizontal gene transfer involves the uptake of naked DNA from the environment?

Accepted Answer

Transformation

Question 8

What is the clinical significance of R-plasmids in bacteria?

Accepted Answer

They confer resistance to antibiotics

Question 9

Which of the following best describes the role of transposons in bacterial genomes?

Accepted Answer

They can move antibiotic resistance genes between plasmids and chromosomes

Question 10

A bacterium acquires a new trait after being infected by a bacteriophage that carries bacterial DNA from a previous host. This process is called:

Accepted Answer

Transduction

Question 11

Which of the following equations correctly represents the mutation rate if 3 mutations are observed after 1,000 cell divisions?

Accepted Answer

$$	ext{Mutation rate} = \frac{3}{1000}$$

Question 12

Which of the following is NOT a mechanism of horizontal gene transfer in bacteria?

Accepted Answer

Binary fission

Question 13

Which repair mechanism is responsible for removing thymine dimers caused by UV radiation?

Accepted Answer

Nucleotide excision repair

Question 14

A bacterial cell with an F plasmid that has integrated into its chromosome is called:

Accepted Answer

Hfr cell

Question 15

Which of the following best explains why there are so many strains of Escherichia coli?

Accepted Answer

High rates of mutation and horizontal gene transfer

Question 16

Which of the following is a likely outcome if a bacterium acquires a plasmid carrying multiple antibiotic resistance genes during an epidemic?

Accepted Answer

The bacterium can survive treatment with several antibiotics

Question 17

Which of the following statements about mutagens is correct?

Accepted Answer

Mutagens increase the mutation rate by 10-1000 fold

Question 18

Which of the following best describes the clinical significance of the findings from the 1989-1990 Salmonella typhi epidemic in Calcutta?

Accepted Answer

Most isolates were resistant to multiple antibiotics due to the presence of plasmids

Question 19

Which of the following is a feature of plasmids that contributes to their role in spreading antibiotic resistance?

Accepted Answer

They can be transferred both vertically and horizontally

Question 20

Which of the following best describes the difference between generalized and specialized transduction?

Accepted Answer

Generalized transduction can transfer any bacterial gene, while specialized transduction transfers only genes near the prophage integration site

Microbial Genetics: Mechanisms of Genetic Change and Diversity in Bacteria

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