Question 1

Which of the following best explains why most bacteria grow optimally at neutral pH and moderate temperatures?

Accepted Answer

Enzyme activity is maximized under these conditions, allowing efficient metabolism.

Question 2

A microbiologist is culturing two bacterial species. Species A requires organic carbon sources, while Species B can use CO$_2$ as its sole carbon source. Which classification best describes Species B?

Accepted Answer

Autotroph

Question 3

Which equation correctly models exponential microbial growth, where $N$ is the final cell number, $N_0$ is the initial cell number, and $n$ is the number of generations?

Accepted Answer

$N = N_0 	imes 2^n$

Question 4

During which phase of the bacterial growth curve does the population size remain constant, and why?

Accepted Answer

Stationary phase, because nutrient depletion and waste accumulation balance cell division and death.

Question 5

Which of the following is a key difference between binary fission and budding in microbial reproduction?

Accepted Answer

Binary fission produces two identical cells, while budding produces a parent and a smaller daughter cell.

Question 6

A hospital is deciding between using moist heat and chemical disinfectants to control microbial growth on surgical instruments. Which factor should be considered when choosing the method?

Accepted Answer

The type of material being sterilized and the spectrum of microbial targets.

Question 7

Which of the following best describes the mechanism of action of beta-lactam antibiotics such as penicillin?

Accepted Answer

They inhibit cell wall synthesis by blocking peptidoglycan cross-linking.

Question 8

A patient develops resistance to an antimicrobial drug after prolonged use. Which microbial mechanism is most likely responsible?

Accepted Answer

Acquisition of a gene encoding an enzyme that degrades the drug.

Question 9

Which of the following statements correctly contrasts viruses and prions?

Accepted Answer

Viruses contain nucleic acids, while prions are composed only of protein.

Question 10

Which step is unique to the lysogenic cycle of bacteriophage replication compared to the lytic cycle?

Accepted Answer

Integration of phage DNA into the host genome as a prophage.

Question 11

A scientist is studying gene expression in prokaryotes and eukaryotes. Which process is found in eukaryotes but not in prokaryotes?

Accepted Answer

RNA splicing to remove introns from pre-mRNA.

Question 12

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

Accepted Answer

The movement of genetic material between organisms by transformation, transduction, or conjugation.

Question 13

Which antimicrobial drug mechanism would be most effective against a virus with an envelope?

Accepted Answer

Inhibition of viral entry by blocking envelope fusion with the host cell membrane.

Question 14

Which of the following is a plausible reason why bacteria are generally more susceptible to penicillin than viruses?

Accepted Answer

Bacteria have peptidoglycan cell walls targeted by penicillin, while viruses lack cell walls.

Question 15

Which of the following equations can be used to estimate the generation time $g$ of a bacterial population, given the initial cell number $N_0$, final cell number $N$, and elapsed time $t$?

Accepted Answer

$g = \frac{t}{n}$,\ where\ n = \frac{\log_{10}(N) - \log_{10}(N_0)}{\log_{10}(2)}$

Question 16

Which of the following best describes the role of mutations in microbial genetics?

Accepted Answer

Mutations introduce genetic variation, which can lead to new traits and adaptation.

Question 17

A patient is infected with a virus that integrates its genome into host DNA and remains dormant for years. Which type of viral infection is this?

Accepted Answer

Latent infection

Question 18

Which of the following is a real-world example of horizontal gene transfer leading to antibiotic resistance?

Accepted Answer

A bacterium acquires a plasmid encoding beta-lactamase from another bacterium via conjugation.

Question 19

Which of the following best describes the process of translation in cells?

Accepted Answer

The synthesis of proteins from mRNA by ribosomes.

Question 20

Which of the following is a significant outcome of antimicrobial therapy as it relates to human health?

Accepted Answer

Reduction of pathogenic microbes, but possible disruption of normal microbiota.

Microbial Growth, Genetics, Control, and Virology: Study Guide

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