Question 1

Which of the following statements best explains why viruses are considered exceptions to the classic definition of a microorganism?

Accepted Answer

Viruses are not living because they lack key characteristics of life.

Question 2

Which of the following is a unique feature of archaeal cell membranes compared to bacterial cell membranes?

Accepted Answer

Use of ether-linked lipids and terpenoids.

Question 3

A microbiologist isolates a bacterium that can survive in extremely high salt concentrations (20% NaCl). Which adaptation is most likely present in this organism?

Accepted Answer

Specialized pumps to export Na+ and import K+.

Question 4

Which of the following best describes the function of the FtsZ protein in bacterial cell division?

Accepted Answer

It forms a ring at the cell center to initiate septum formation.

Question 5

A patient sample is cultured on MacConkey agar. The colonies are pink and the organism is Gram-negative. What does this indicate about the organism?

Accepted Answer

It is Gram-negative and ferments lactose.

Question 6

Which of the following is a reason why peptidoglycan synthesis is an effective target for antibiotics?

Accepted Answer

Peptidoglycan is unique to bacteria and essential for their survival.

Question 7

Which of the following best describes the difference between generation time ($$g) $$and growth rate constant ($$k) in $$bacterial cultures?

Accepted Answer

$$g is $$the time per generation, $$k is $$the number of generations per unit time.

Question 8

A bacterium is found to grow optimally at pH 2 and high temperatures. Which adaptations would you expect to find in its cell membrane?

Accepted Answer

Tetraether lipids to decrease H+ permeability.

Question 9

Which of the following statements about Koch’s postulates is correct?

Accepted Answer

They require the pathogen to be isolated and cause disease in a healthy host.

Question 10

Which of the following best explains why most bacteria in the environment are considered 'unculturable'?

Accepted Answer

They require specific growth factors not provided in standard laboratory media.

Question 11

A researcher is studying a bacterium that can grow with or without oxygen, using both fermentation and respiration. Which term best describes this organism?

Accepted Answer

Facultative anaerobe

Question 12

Which of the following is a function of the S-layer in Gram-positive bacteria?

Accepted Answer

Biofilm formation and host interaction

Question 13

Which of the following best describes the role of siderophores in bacterial nutrition?

Accepted Answer

They scavenge iron from the environment and deliver it to the cell.

Question 14

A bacterium is found to be metabolically dormant, highly resistant to heat, and can survive for thousands of years. In which differentiated state is this bacterium most likely found?

Accepted Answer

Spore

Question 15

Which of the following physical agents is NOT addressed by a jerky recipe that uses vinegar, salt, dehydration, and cool storage?

Accepted Answer

Barometric pressure

Question 16

Which of the following best describes the function of group translocation in bacterial cells?

Accepted Answer

It chemically modifies the substrate during transport into the cell.

Question 17

Which of the following is a key adaptation of thermophilic bacteria that allows them to survive at high temperatures?

Accepted Answer

Highly stable proteins with extensive hydrogen bonding.

Question 18

Which of the following is a plausible reason why phage therapy was largely ignored after its discovery in the early 1900s?

Accepted Answer

The discovery of antibiotics provided a more effective treatment for bacterial infections.

Question 19

Which of the following best describes the main advantage of using optical density to count bacteria in a culture?

Accepted Answer

It provides same-day results and is easy to perform.

Question 20

A mutant bacterium lacks the gene for a chemoreceptor. Which phenotype would you expect to observe?

Accepted Answer

The bacterium can swim but cannot move toward or away from chemical gradients.

Microbiology: Foundations, Cell Structure, Growth, and Control

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