Question 1

Which of the following best describes a chemotroph?

Accepted Answer

An organism that obtains energy from organic or inorganic chemicals.

Question 2

A bacterium isolated from a hot spring that grows optimally at $$70^{\circ}C$ is most likely classified as which type?

Accepted Answer

Thermophile

Question 3

Which of the following is NOT a major chemical element required for microbial growth?

Accepted Answer

Calcium

Question 4

Obligate anaerobes are harmed by oxygen because they:

Accepted Answer

Lack enzymes to detoxify reactive oxygen species.

Question 5

Which toxic form of oxygen is most likely to cause irreparable damage to cellular components due to its high reactivity?

Accepted Answer

Hydroxyl radical

Question 6

A bacterium that grows throughout a thioglycolate broth but prefers low oxygen concentrations is classified as:

Accepted Answer

Microaerophile

Question 7

Which of the following best explains why nitrogen fixation by certain bacteria is essential to life?

Accepted Answer

It converts atmospheric $$N_2$$ into ammonia, making nitrogen available for amino acids and nucleotides.

Question 8

Which of the following media types is designed to distinguish between different types of bacteria based on their metabolic activities?

Accepted Answer

Differential media

Question 9

A researcher wants to isolate a pure culture from a mixed bacterial sample. Which method is most appropriate?

Accepted Answer

Streak-plate method

Question 10

Which of the following best describes the stationary phase in a bacterial growth curve?

Accepted Answer

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

Question 11

A halophile is most likely to grow on which type of agar?

Accepted Answer

Mannitol salt agar

Question 12

Which method would be most appropriate for estimating the number of bacteria in a water sample when the population is expected to be very low?

Accepted Answer

Membrane filtration

Question 13

Which equation best represents binary fission in bacteria, where $$N is $$the final number of cells, $$N_0 is $$the initial number of cells, and $$n is $$the number of generations?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 14

Which of the following is a reason why biofilms are more resistant to antibiotics than planktonic (free-living) bacteria?

Accepted Answer

Biofilms produce extracellular polymeric substances that limit antibiotic penetration.

Question 15

Which of the following is a trace element required by microbes in only small amounts?

Accepted Answer

Iron

Question 16

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 17

Which of the following best explains why enzymes are essential for microbial metabolism?

Accepted Answer

They speed up the rate of chemical reactions without being used up.

Question 18

A researcher uses a spectrophotometer to measure the turbidity of a bacterial culture. What is being estimated?

Accepted Answer

The total cell mass, including both live and dead cells.

Question 19

Which of the following is a growth factor required by some bacteria?

Accepted Answer

Amino acids

Question 20

Which of the following best describes the effect of high temperature on microbial cell membranes?

Accepted Answer

Membranes become too fluid, losing integrity.

Microbial Nutrition and Growth: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard