Question 1

Which of the following best describes a chemoheterotroph?

Accepted Answer

An organism that uses organic compounds for both energy and carbon.

Question 2

A bacterial culture is in the stationary phase of the growth curve. Which of the following best explains what is happening?

Accepted Answer

The rate of cell division equals the rate of cell death.

Question 3

Which equation would you use to calculate the total number of bacteria after a certain number of generations, given the initial number of cells?

Accepted Answer

$$N_{total} = (N_{initial})2^n$$

Question 4

A patient develops a persistent infection on a hip implant. Which microbial structure is most likely responsible for the difficulty in treating this infection?

Accepted Answer

Biofilm

Question 5

Which of the following best describes nitrogen fixation?

Accepted Answer

The reduction of nitrogen gas (N$$_2) to $$ammonia (NH$$_4^+) by $$certain bacteria.

Question 6

Which of the following organisms would be most likely to grow in a refrigerator at 4$$^\circC$$?

Accepted Answer

Psychrophile

Question 7

Why are biofilm-associated infections particularly difficult to treat?

Accepted Answer

Biofilms protect bacteria from antibiotics and the immune system.

Question 8

Which of the following best describes a facultative anaerobe?

Accepted Answer

An organism that can grow with or without oxygen.

Question 9

A bacterial culture is exposed to a pH of 3. Which group of bacteria is most likely to thrive?

Accepted Answer

Acidophiles

Question 10

Which of the following is a real-world example of a beneficial biofilm?

Accepted Answer

Biofilm in a septic tank aiding in waste breakdown

Question 11

Which of the following is a trace element required in small amounts for microbial growth?

Accepted Answer

Iron

Question 12

A scientist isolates a bacterium from a hot spring that grows optimally at 80$$^\circC. $$This organism is best classified as a:

Accepted Answer

Hyperthermophile

Question 13

Which phase of the bacterial growth curve is most appropriate for Gram staining and antibiotic susceptibility testing?

Accepted Answer

Logarithmic (log) phase

Question 14

Which of the following best explains why water is essential for microbial growth?

Accepted Answer

Water dissolves enzymes, salts, and nutrients required for metabolism.

Question 15

A bacterial cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell will shrink due to water loss.

Question 16

Which of the following is NOT a growth factor for bacteria?

Accepted Answer

Glucose

Question 17

A culture medium contains only inorganic salts and CO$$_2 as a $$carbon source. Which type of organism could grow in this medium?

Accepted Answer

Photoautotroph

Question 18

Which of the following best describes the process of quorum sensing in biofilm formation?

Accepted Answer

Cells communicate using chemical signals to coordinate behavior.

Question 19

A scientist wants to estimate the number of viable bacteria in a sample. Which method should they use?

Accepted Answer

Serial dilution and standard plate count

Question 20

Which of the following is a real-life consequence of biofilm formation in household plumbing?

Accepted Answer

Clogged drains and pipes

Microbial Nutrition and Growth: Study Guide and Key Concepts

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