Question 1

Which of the following best describes the main genetic element in prokaryotes?

Accepted Answer

A single circular chromosome containing all or most essential genes

Question 2

Which statement about plasmids is CORRECT?

Accepted Answer

Plasmids replicate independently of the host chromosome

Question 3

A researcher finds a DNA segment in a bacterial genome with a GC content significantly different from the rest of the genome. What is the most likely explanation?

Accepted Answer

The segment was acquired through horizontal gene transfer

Question 4

Which of the following is a function commonly encoded by plasmids in bacteria?

Accepted Answer

Antibiotic resistance

Question 5

What is the difference between the core genome and the pan genome of a microbial species?

Accepted Answer

The core genome includes genes shared by all strains, while the pan genome includes all genes found in any strain

Question 6

Which of the following best describes a resistance plasmid?

Accepted Answer

A plasmid that confers resistance to antibiotics and other growth inhibitors

Question 7

A pathogenic bacterium is found to produce a toxin only when a specific plasmid is present. What is the most likely explanation?

Accepted Answer

The gene encoding the toxin is located on the plasmid

Question 8

Which of the following is a characteristic of chromosomal islands?

Accepted Answer

They contain clusters of genes for specialized functions, often acquired by horizontal gene transfer

Question 9

Which of the following is an example of horizontal gene transfer?

Accepted Answer

A bacterium acquiring a plasmid from another bacterium via conjugation

Question 10

Which of the following best describes metagenomics?

Accepted Answer

The analysis of pooled DNA or RNA from an environmental sample containing organisms that have not been isolated or identified

Question 11

Which of the following statements about bacteriocins is TRUE?

Accepted Answer

Bacteriocins are proteins encoded on plasmids that inhibit or kill closely related species or strains

Question 12

A scientist is studying a bacterial strain that can fix nitrogen only when a certain plasmid is present. What is the most likely explanation?

Accepted Answer

The plasmid encodes genes required for nitrogen fixation

Question 13

Which of the following is a key feature of conjugative plasmids?

Accepted Answer

They can be transferred between bacteria via direct cell-to-cell contact

Question 14

Which of the following best explains why the human gut microbiome is important for health?

Accepted Answer

It contains a large number of prokaryotic cells, mainly Bacteroidetes and Firmicutes, which influence metabolism and obesity

Question 15

Which of the following is a correct statement about the Escherichia coli K-12 chromosome?

Accepted Answer

It is a single circular DNA molecule of approximately 4,639,675 base pairs

Question 16

A gene found in only some strains of a bacterial species, but not all, is part of which genome?

Accepted Answer

The pan genome

Question 17

Which of the following is a likely consequence of horizontal gene transfer in bacteria?

Accepted Answer

Rapid acquisition of new traits such as antibiotic resistance

Question 18

Which of the following best describes a pathogenicity island?

Accepted Answer

A chromosomal island that encodes virulence factors

Question 19

Which of the following is NOT a typical feature of plasmids?

Accepted Answer

They are always essential for host survival

Question 20

A metagenomic study of soil reveals a gene with a codon usage pattern very different from the dominant bacterial species. What is the most likely explanation?

Accepted Answer

The gene was acquired by horizontal gene transfer from a different organism

Ch. 6,10,13 - Genetic Elements in Prokaryotes: Chromosomes and Plasmids

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