Question 1

Which of the following best describes a chemoorganotroph?

Accepted Answer

An organism that degrades large organic molecules to obtain both carbon and energy.

Question 2

A bacterium is placed in a solution with a higher concentration of solutes than inside the cell. What is the most likely outcome for the cell?

Accepted Answer

The cell will shrink as water diffuses out, a process known as plasmolysis.

Question 3

Which of the following is NOT a macronutrient required by microorganisms?

Accepted Answer

Zinc

Question 4

A microbe that can utilize oxygen when it is present but can also grow in its absence is classified as a:

Accepted Answer

Facultative anaerobe

Question 5

Which equation correctly calculates the final population size ($$N_f) of a $$bacterial culture after $$n$$ generations, starting with $$N_i$$ cells?

Accepted Answer

$$N_f = (N_i)2^n$$

Question 6

Which of the following best describes the role of group translocation in microbial cells?

Accepted Answer

It transports molecules into the cell and chemically modifies them during transport.

Question 7

A bacterium that grows optimally at 37$$^\circC $$and is commonly found in the human body would be classified as a:

Accepted Answer

Mesophile

Question 8

Which of the following is an example of a mutualistic relationship?

Accepted Answer

A fungus and a plant root forming mycorrhizae, where both benefit.

Question 9

Which of the following transport mechanisms requires energy and moves substances against their concentration gradient?

Accepted Answer

Carrier-mediated active transport

Question 10

A microbe that requires high salt concentrations for growth is called a(n):

Accepted Answer

Obligate halophile

Question 11

Which of the following statements about biofilms is TRUE?

Accepted Answer

Biofilms form when cells attach to a surface and produce an extracellular matrix.

Question 12

Which of the following best explains why obligate anaerobes cannot survive in the presence of oxygen?

Accepted Answer

They lack the enzymes to detoxify reactive oxygen species.

Question 13

A culture of E. coli starts with 5 cells and has a doubling time of 20 minutes. How many cells will there be after 3 hours?

Accepted Answer

2560

Question 14

Which of the following is a micronutrient (trace element) required by some microorganisms?

Accepted Answer

Zinc

Question 15

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of solutes down their concentration gradient with the help of a carrier protein.

Question 16

Which of the following is an example of a saprobe?

Accepted Answer

A fungus that decomposes dead organic matter in soil.

Question 17

Which of the following environmental factors does NOT directly affect the function of microbial enzymes?

Accepted Answer

Cell wall composition

Question 18

A microbe that grows best at a pH of 2 would be classified as a(n):

Accepted Answer

Acidophile

Question 19

Which of the following is a real-life example of commensalism?

Accepted Answer

Haemophilus bacteria growing near Staphylococcus colonies to absorb growth factors.

Question 20

Which of the following statements about microbial growth curves is correct?

Accepted Answer

The stationary phase occurs when nutrients are depleted and waste products accumulate.

Chapter 7-Microbial Nutrition, Ecology, and Growth: Study Notes

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