Question 1

Which of the following statements about prokaryotic and eukaryotic genomes is correct?

Accepted Answer

Prokaryotic genomes are typically organized in 1–3 circular chromosomes located in the nucleoid region.

Question 2

A bacterial cell is exposed to lactose but no glucose. Which regulatory mechanism allows the cell to produce enzymes to digest lactose?

Accepted Answer

The lac operon is induced, as allolactose binds to and inactivates the repressor, allowing transcription.

Question 3

Which type of horizontal gene transfer involves a pilus and the transfer of a fertility plasmid between bacterial cells?

Accepted Answer

Conjugation

Question 4

A bacteriophage infects a bacterial cell and immediately begins producing new phage particles, eventually lysing the cell. Which replication pathway is this?

Accepted Answer

Lytic replication

Question 5

Which of the following best describes the role of viral spikes (peplomers) in infection?

Accepted Answer

They help viruses attach and gain entry to specific host cells, determining host range and tissue tropism.

Question 6

A patient is diagnosed with variant Creutzfeldt-Jakob disease (vCJD). Which infectious agent is responsible for this disease?

Accepted Answer

A prion, which is an infectious protein with no genetic material

Question 7

Which physical method is capable of sterilizing medical supplies that cannot be autoclaved, by damaging nucleic acids?

Accepted Answer

Ionizing radiation (gamma rays and X-rays)

Question 8

A bacterial culture is grown in a closed batch system. After a period of rapid exponential growth, the population growth rate levels off as nutrients decrease and waste accumulates. Which phase is this?

Accepted Answer

Stationary phase

Question 9

Which equation correctly represents the ATP–ADP cycling process?

Accepted Answer

$$\mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P}$$

Question 10

Which of the following best explains why RNA viruses mutate more rapidly than DNA viruses?

Accepted Answer

RNA polymerases lack proofreading capabilities, leading to frequent mutations.

Question 11

A microbe grows best at pH 1–5 and uses proton pumps to maintain a neutral cytoplasmic pH. Which classification best fits this organism?

Accepted Answer

Acidophile

Question 12

Which of the following is a correct description of fermentation?

Accepted Answer

Fermentation is an incomplete oxidation of glucose, uses organic compounds as terminal electron acceptors, and yields about 2 ATP molecules.

Question 13

Which of the following equations represents a redox reaction commonly used in cellular metabolism?

Accepted Answer

$$\mathrm{O}_2 + 4e^- + 4\mathrm{H}^+ \rightarrow 2\mathrm{H}_2\mathrm{O}$$

Question 14

Which type of media would you use to visually differentiate between two bacterial species based on their metabolic properties?

Accepted Answer

Differential media

Question 15

A hospital needs to sterilize surgical instruments that are sensitive to moisture and heat. Which chemical germicide is most appropriate?

Accepted Answer

Ethylene oxide gas

Question 16

Which of the following best describes the function of an enzyme in a metabolic pathway?

Accepted Answer

Enzymes hold reactants in proper orientation and lower the activation energy, increasing reaction rate.

Question 17

A scientist uses the streak plate technique to isolate bacteria from a clinical sample. What is the primary purpose of this method?

Accepted Answer

To decrease cell concentration and isolate individual colonies for identification.

Question 18

Which of the following is a plausible outcome of antigenic shift in influenza viruses?

Accepted Answer

Major genetic reassortment leading to new viral strains with increased infectivity and expanded host range.

Question 19

Which of the following best describes the difference between disinfectants and antiseptics?

Accepted Answer

Disinfectants are used to treat inanimate objects, while antiseptics are applied to living tissue.

Question 20

A bacterial species is found growing near hydrothermal vents at temperatures between 65°C and 120°C. Which classification best fits this organism?

Accepted Answer

Extreme thermophile

Microbiology Study Guide: Genetics, Viruses & Prions, Microbial Growth, and Metabolism

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