Question 1

Which of the following best describes the main difference between vertical gene transfer (VGT) and horizontal gene transfer (HGT) in bacteria?

Accepted Answer

VGT transfers DNA from parent to offspring during reproduction, while HGT transfers DNA between unrelated cells without reproduction.

Question 2

In Frederick Griffith’s experiment with Streptococcus pneumoniae, what was the key finding that led to the discovery of the 'transforming principle'?

Accepted Answer

Live R strain mixed with heat-killed S strain caused disease, and live S bacteria were recovered from the mouse.

Question 3

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

Accepted Answer

Binary fission

Question 4

A bacterium acquires antibiotic resistance by taking up free DNA from its environment. Which process is responsible for this genetic change?

Accepted Answer

Transformation

Question 5

During generalized transduction, which of the following best describes the DNA that is transferred to a new bacterial cell?

Accepted Answer

Random fragments of the host bacterial DNA

Question 6

Which of the following statements about the F plasmid is TRUE?

Accepted Answer

It encodes the proteins necessary for pilus formation.

Question 7

What is the primary genetic outcome when an Hfr cell conjugates with an F⁻ cell?

Accepted Answer

The F⁻ cell gains new chromosomal genes but usually remains F⁻.

Question 8

Which of the following best explains why it is difficult to trace the genetic ancestry of microbes compared to animals?

Accepted Answer

Microbes frequently exchange DNA horizontally, creating mosaic genomes.

Question 9

A transposon inserts into the coding region of a gene, causing a frameshift mutation. What is the most likely consequence?

Accepted Answer

The gene becomes nonfunctional due to altered reading frame.

Question 10

Which of the following is a key feature that distinguishes complex transposons from simple insertion sequences (IS elements)?

Accepted Answer

Carrying additional genes such as antibiotic resistance

Question 11

A bacterium receives a plasmid carrying a transposon with an antibiotic resistance gene via conjugation. Which processes are involved in the spread of this resistance gene?

Accepted Answer

Both conjugation and transposition

Question 12

Which enzyme is directly responsible for sealing the nicks in DNA during the ligation step of genetic recombination?

Accepted Answer

DNA ligase

Question 13

In the context of bacterial conjugation, what is the function of the sex pilus?

Accepted Answer

To attach the donor cell to the recipient cell and initiate DNA transfer

Question 14

Which of the following best describes replicative transposition?

Accepted Answer

The transposon is copied, and the new copy inserts elsewhere while the original remains.

Question 15

Which mechanism of horizontal gene transfer requires the recipient cell to be competent?

Accepted Answer

Transformation

Question 16

A bacteriophage accidentally packages host bacterial DNA during the lytic cycle and transfers it to another bacterium. This process is known as:

Accepted Answer

Generalized transduction

Question 17

Which of the following is a direct consequence of transposon activity in a bacterial genome?

Accepted Answer

Genome rearrangements such as deletions, inversions, and duplications

Question 18

Which of the following equations best represents the process of genetic recombination between two homologous DNA molecules?

Accepted Answer

$DNA_A + DNA_B \xrightarrow{recombination} Recombinant\ DNA_{A'} + Recombinant\ DNA_{B'}$

Question 19

Which of the following scenarios best illustrates the role of Hfr cells in bacterial evolution?

Accepted Answer

A bacterium integrates the F plasmid into its chromosome and transfers chromosomal genes to an F⁻ cell during conjugation.

Microbial Genetics: Genetic Recombination, Horizontal and Vertical Gene Transfer, and Transposons

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