Question 1

Which of the following statements best describes why viruses are considered obligate intracellular parasites?

Accepted Answer

They require a host cell to replicate and perform metabolic activities.

Question 2

A bacteriophage infects a bacterial cell and integrates its DNA into the host genome, remaining dormant for several generations. What is this process called?

Accepted Answer

Lysogenic cycle

Question 3

Which structure is responsible for enclosing the viral genome and can have a variety of shapes?

Accepted Answer

Capsid

Question 4

A virus with a single-stranded RNA genome and a membranous envelope infects animal cells. Which of the following is most likely true about this virus?

Accepted Answer

It is an animal virus with the broadest variety of RNA genomes.

Question 5

Which of the following best explains the role of restriction enzymes in bacterial defense against phages?

Accepted Answer

They cut foreign DNA, such as phage DNA, preventing infection.

Question 6

In the CRISPR-Cas system, what is the function of the RNA transcript derived from the CRISPR region?

Accepted Answer

It binds to Cas proteins and guides them to complementary phage DNA for cleavage.

Question 7

Which of the following is NOT a method of genetic recombination in prokaryotes?

Accepted Answer

Binary fission

Question 8

A prokaryote is found living in a hot spring with temperatures above 80°C. Which group does it most likely belong to?

Accepted Answer

Extreme thermophiles

Question 9

Which of the following equations correctly represents the process of nitrogen fixation carried out by some prokaryotes?

Accepted Answer

$\mathrm{N_2 + 8H^+ + 8e^- \rightarrow 2NH_3 + H_2}$

Question 10

Which of the following statements about prokaryotic reproduction is correct?

Accepted Answer

Prokaryotes reproduce by binary fission, which can occur every 1-3 hours under optimal conditions.

Question 11

A scientist discovers a prokaryote that can survive with or without oxygen, switching between aerobic respiration and fermentation. What is this organism classified as?

Accepted Answer

Facultative anaerobe

Question 12

Which of the following best describes horizontal gene transfer in prokaryotes?

Accepted Answer

Movement of genes among individuals from different species.

Question 13

Which of the following is a correct description of a plasmid?

Accepted Answer

A smaller ring of independently replicating DNA found in prokaryotes.

Question 14

Which metabolic adaptation allows some prokaryotes to use light as an energy source and $\mathrm{CO_2}$ as a carbon source?

Accepted Answer

Photoautotrophy

Question 15

During the lytic cycle of a bacteriophage, which event leads directly to the destruction of the host cell?

Accepted Answer

Self-assembly of new phage particles and release of phages

Question 16

Which of the following is a distinguishing feature of archaea compared to bacteria?

Accepted Answer

Branched hydrocarbon chains in membrane lipids

Question 17

A patient is infected with a virus that permanently integrates its DNA into the host genome and uses host polymerase to transcribe viral genes. What is this integrated viral DNA called?

Accepted Answer

Provirus

Question 18

Which of the following best explains why mutation rates, although low per generation, can lead to rapid evolution in prokaryotes?

Accepted Answer

Prokaryotes have large populations and short generation times, so mutations accumulate quickly.

Question 19

Which of the following is a real-world application of the CRISPR-Cas system in biotechnology?

Accepted Answer

Precise editing of genes in living organisms

Question 20

Which of the following best describes the host range of a virus?

Accepted Answer

The limited number of host cells that a virus can infect

Viruses and Prokaryotes: Structure, Replication, and Diversity

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