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 bacterium is found growing at the bottom of a lake where oxygen is absent. It dies when exposed to atmospheric oxygen. Which term best describes this organism?

Accepted Answer

Obligate anaerobe

Question 3

Which toxic form of oxygen is the most reactive and is NOT typically formed in aerobic cells?

Accepted Answer

Hydroxyl radical

Question 4

Nitrogen fixation is essential for life on Earth because:

Accepted Answer

It converts N$$_2$$ into NH$$_3$$, a usable form for most organisms.

Question 5

Which of the following best describes a biofilm?

Accepted Answer

A collection of microbes living on a surface in a complex community.

Question 6

A bacterium that grows best at 37$$^	ext{o}C $$and is commonly found in the human body is classified as a:

Accepted Answer

Mesophile

Question 7

Which of the following media would you use to distinguish between lactose-fermenting and non-lactose-fermenting Gram-negative bacteria?

Accepted Answer

MacConkey agar

Question 8

A scientist wants to maintain a bacterial culture in the log phase of growth for industrial production. Which device should be used?

Accepted Answer

Chemostat

Question 9

Which of the following statements about osmotic pressure is correct?

Accepted Answer

Obligate halophiles require high salt concentrations to survive.

Question 10

A microbiologist is using a serial dilution and viable plate count method. She counts 80 colonies on a plate inoculated with 0.1 mL of a 10$$^{-4}$$ dilution. What is the original concentration of bacteria per mL?

Accepted Answer

$$8 	imes 10^6$ CFU/mL

Question 11

Which of the following best explains why antibiotics are most effective during the log phase of bacterial growth?

Accepted Answer

Cells are actively synthesizing DNA and proteins.

Question 12

Which of the following is a direct method for measuring microbial growth that does NOT require incubation?

Accepted Answer

Microscopic cell count using a cell counter

Question 13

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

Accepted Answer

Facultative anaerobe

Question 14

Which of the following is NOT a growth factor?

Accepted Answer

Water

Question 15

Which of the following best describes the function of superoxide dismutase in aerobic organisms?

Accepted Answer

It reduces superoxide radicals to hydrogen peroxide.

Question 16

Which of the following statements about defined and complex media is correct?

Accepted Answer

Complex media are useful when the nutritional needs of an organism are unknown.

Question 17

A scientist is studying a bacterium that grows optimally at pH 9. Which term best describes this organism?

Accepted Answer

Alkalinophile

Question 18

Which of the following is a reason why most prokaryotes have not been grown in culture medium?

Accepted Answer

Their nutritional requirements are unknown or too complex.

Question 19

Which of the following best describes the process of binary fission?

Accepted Answer

A cell elongates, replicates its chromosome, forms a septum, and divides into two cells.

Question 20

Which of the following is a real-world application of using a chemostat?

Accepted Answer

Maintaining a microbial population in log phase for industrial fermentation.

Microbial Nutrition and Growth: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard