Question 1

Which of the following best describes a chemoheterotroph?

Accepted Answer

An organism that uses organic compounds as both an energy and carbon source.

Question 2

A bacterium is isolated from a deep-sea hydrothermal vent. It grows optimally at 90°C and requires high pressure to maintain its cellular structure. Which terms best describe this organism?

Accepted Answer

Hyperthermophile and barophile

Question 3

Which of the following statements about biofilms is TRUE?

Accepted Answer

Biofilms form as a result of quorum sensing, which triggers changes in gene expression.

Question 4

A microbiologist wants to isolate a pure culture of a bacterium from a mixed sample. Which technique should she use?

Accepted Answer

Streak plate method

Question 5

Which of the following is a toxic form of oxygen that can cause irreparable damage to cells?

Accepted Answer

Hydroxyl radical

Question 6

A bacterial culture is placed in a medium with a pH of 5.5. Which group of bacteria is most likely to thrive in this environment?

Accepted Answer

Acidophiles

Question 7

Which equation correctly describes the number of cells ($N$) after $n$ generations, starting from a single cell, during binary fission?

Accepted Answer

$N = 2^n$

Question 8

A sample is diluted 1:1000 and 0.1 mL is plated. After incubation, 50 colonies are counted. What is the original concentration of bacteria in the sample (CFU/mL)?

Accepted Answer

$5 	imes 10^5$ CFU/mL

Question 9

Which of the following best explains why obligate anaerobes are killed by oxygen?

Accepted Answer

They lack enzymes to detoxify reactive oxygen species.

Question 10

Which type of culture medium would you use to distinguish between bacteria that can ferment lactose and those that cannot?

Accepted Answer

Differential medium

Question 11

A hospital-acquired infection is traced to a contaminated catheter. Why are biofilms on medical devices particularly concerning for healthcare workers?

Accepted Answer

Biofilms protect microbes from antibiotics and immune responses.

Question 12

Which of the following is NOT a direct method for measuring microbial growth?

Accepted Answer

Spectrophotometry (turbidity)

Question 13

A bacterium that can grow in the presence or absence of oxygen, but grows better with oxygen, is classified as:

Accepted Answer

Facultative anaerobe

Question 14

Which of the following best describes the function of a chemostat in industrial microbiology?

Accepted Answer

Maintains a microbial population in a particular phase of growth by continuously adding fresh medium and removing old medium.

Question 15

Which of the following is a growth factor required by some microorganisms for nucleic acid synthesis?

Accepted Answer

Para-aminobenzoic acid (PABA)

Question 16

A microbiologist is working with a bacterium that cannot synthesize NADH. What type of substance must be added to the medium to support its growth?

Accepted Answer

A growth factor

Question 17

Which of the following best explains why some bacteria can survive in the death phase of a growth curve and later regrow when transferred to fresh media?

Accepted Answer

Some cells remain viable and can resume growth when nutrients become available.

Question 18

Which of the following best describes the effect of temperature on the growth of lipid-containing membranes in microbes?

Accepted Answer

Low temperatures make membranes rigid and fragile; high temperatures make them too fluid.

Question 19

Which of the following is the correct formula for calculating the number of generations ($n$) if you start with $N_0$ cells and end with $N$ cells?

Accepted Answer

$n = \frac{\log N - \log N_0}{\log 2}$

Question 20

Which of the following best describes why clinical laboratory scientists keep many different kinds of culture media on hand?

Accepted Answer

Different microbes have unique nutritional and environmental requirements for growth.

Microbial Nutrition and Growth: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards