Question 1

Which of the following statements best describes the process of 'headful' packaging in bacteriophage T4 replication?

Accepted Answer

The capsid is filled with DNA until it reaches capacity, resulting in each virion containing slightly more than one genome length and terminal redundancy.

Question 2

A bacteriophage infects E. coli and integrates its genome into the host chromosome, remaining dormant until environmental stress triggers its reactivation. What is the integrated viral DNA called?

Accepted Answer

Prophage

Question 3

Which of the following best explains why phage therapy is considered a promising alternative to antibiotics in treating multidrug-resistant bacterial infections?

Accepted Answer

Phages can evolve alongside bacteria, are highly specific, and can be combined with antibiotics for increased efficacy.

Question 4

During the lytic cycle of bacteriophage T4, which enzyme is responsible for degrading the bacterial cell wall to release progeny virions?

Accepted Answer

Lysozyme

Question 5

In the lambda phage genetic switch, which protein promotes lysogeny by activating the expression of the cI repressor?

Accepted Answer

CII

Question 6

Which of the following is a key difference between the infection cycles of animal viruses and bacteriophages?

Accepted Answer

Animal viruses often enter the host cell with their entire capsid, whereas bacteriophages typically inject only their genome.

Question 7

A virus with a segmented dsRNA genome that replicates in a viroplasm and causes severe diarrhea in infants is most likely:

Accepted Answer

Rotavirus

Question 8

Which of the following best describes the role of leghemoglobin in the root nodules of legumes?

Accepted Answer

It binds oxygen to maintain low O2 levels, protecting nitrogenase while allowing aerobic respiration.

Question 9

Which of the following statements about the Baltimore classification scheme is correct?

Accepted Answer

It groups viruses based on the pathway they use to produce mRNA.

Question 10

Which of the following is a plausible consequence of denitrification in agricultural soils?

Accepted Answer

Loss of fertilizer nitrogen to the atmosphere as N2 or N2O gases.

Question 11

Which of the following best describes the process of rolling circle replication in lambda phage?

Accepted Answer

The circularized viral DNA is continuously copied, generating long concatemers that are later cut at cos sites.

Question 12

Which of the following is NOT a direct method for measuring bacterial growth?

Accepted Answer

Optical density (turbidity)

Question 13

In a chemostat, which parameter is used to control the growth rate of the microbial population?

Accepted Answer

Dilution rate

Question 14

Which of the following is a key feature of metagenomics?

Accepted Answer

It studies the total gene content of a microbial community directly from environmental samples.

Question 15

Which of the following statements about substrate-level phosphorylation is correct?

Accepted Answer

It directly synthesizes ATP during catabolism of an energy substrate like glucose.

Question 16

Which of the following is a distinguishing feature of fermentation compared to respiration?

Accepted Answer

Fermentation produces ATP solely by substrate-level phosphorylation.

Question 17

Which of the following is a common challenge in genome annotation?

Accepted Answer

Assigning functions to hypothetical proteins with no sequence homology to known proteins.

Question 18

Which of the following best describes the function of the Q protein in lambda phage?

Accepted Answer

It is an anti-terminator required for late lytic gene expression.

Question 19

Which of the following is a plausible reason why plant viruses often require mechanical damage or insect vectors for infection?

Accepted Answer

Plant cells have rigid cell walls that are difficult for viruses to penetrate without assistance.

Question 20

Which of the following is a correct statement about the role of NAD+ in microbial metabolism?

Accepted Answer

NAD+ is reduced to NADH during glycolysis and the citric acid cycle, serving as an electron carrier.

Microbial Virology and Bacterial Metabolism: Core Concepts and Mechanisms

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