Question 1

Which of the following best describes the role of NAD+ in aerobic respiration?

Accepted Answer

NAD+ functions as an electron carrier, accepting electrons during glycolysis and the Krebs cycle.

Question 2

A bacterial culture is grown in a medium with limited nutrients and oxygen. After several hours, the bacteria switch from aerobic respiration to fermentation. Which metabolic pathway is most likely to be upregulated?

Accepted Answer

Glycolysis

Question 3

Which equation correctly represents the net ATP yield from one glucose molecule during aerobic respiration in prokaryotes?

Accepted Answer

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + 38ATP$

Question 4

Which of the following statements about bacterial photosynthesis is correct?

Accepted Answer

Photoautotrophs use light energy to fix carbon dioxide into organic compounds.

Question 5

A bacterium is classified as a psychrophile. Which environment would it most likely thrive in?

Accepted Answer

A refrigerator at $4^\circ C$

Question 6

Which of the following best explains why obligate anaerobes cannot survive in the presence of oxygen?

Accepted Answer

They lack enzymes to neutralize toxic oxygen species such as superoxide radicals.

Question 7

During bacterial growth, which phase is characterized by rapid cell division and exponential increase in population?

Accepted Answer

Log (exponential) phase

Question 8

A researcher wants to determine the minimum inhibitory concentration (MIC) of an antibiotic against E. coli. Which method would be most appropriate?

Accepted Answer

Serial dilution of the antibiotic in broth culture

Question 9

Which of the following statements about bacterial plasmids is correct?

Accepted Answer

Plasmids often carry genes for antibiotic resistance.

Question 10

A mutation occurs in the lac operon of E. coli, causing the repressor protein to be nonfunctional. What is the most likely outcome?

Accepted Answer

The operon will be constitutively expressed, even in the absence of lactose.

Question 11

Which process involves the uptake of naked DNA fragments from the environment by a bacterial cell?

Accepted Answer

Transformation

Question 12

A scientist is studying a bacterium that can survive in extremely acidic environments. Which group does this organism most likely belong to?

Accepted Answer

Extreme acidophiles

Question 13

Which of the following is a correct description of the function of DNA polymerase during bacterial DNA replication?

Accepted Answer

DNA polymerase synthesizes new DNA strands by adding nucleotides to the template strand.

Question 14

A Gram-positive bacterium is identified in a clinical sample. Which cell wall component is most likely present in high amounts?

Accepted Answer

Peptidoglycan

Question 15

Which of the following best describes the process of transduction in bacteria?

Accepted Answer

Transfer of DNA by a bacteriophage from one bacterium to another

Question 16

A dichotomous key is used in microbiology for which primary purpose?

Accepted Answer

To identify organisms based on a series of choices between alternative characteristics

Question 17

Which of the following statements about gene regulation in bacteria is correct?

Accepted Answer

Induction increases gene expression in response to a specific substrate.

Question 18

A bacterial cell is exposed to UV radiation, resulting in a thymine dimer. Which DNA repair mechanism is most likely to be activated?

Accepted Answer

Photoreactivation

Question 19

Which of the following best explains the difference between selective and differential media?

Accepted Answer

Selective media inhibit the growth of certain organisms, while differential media distinguish between organisms based on biochemical properties.

Question 20

A scientist is using PCR to identify a bacterial species. What is the main advantage of this technique?

Accepted Answer

PCR amplifies specific DNA sequences, allowing rapid and sensitive detection of bacteria.

Microbiology Study Guide: Metabolism, Growth, Genetics, and Classification

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