Question 1

Which of the following best describes a chemoheterotroph?

Accepted Answer

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

Question 2

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

Accepted Answer

The cell will undergo plasmolysis as water leaves the cell.

Question 3

Which enzyme is responsible for neutralizing superoxide radicals ($$O_2$$^-$$) in aerobic bacteria?

Accepted Answer

Superoxide dismutase (SOD)

Question 4

A culture starts with 100 bacteria. If the generation time is 30 minutes, how many bacteria will there be after 8 hours? Use the formula $$N = N_0$ 	imes 2^n$$, where $$n is $$the number of generations.

Accepted Answer

$$N = 100 	imes 2$$^{16}$$

Question 5

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

Accepted Answer

They lack enzymes to detoxify reactive oxygen species.

Question 6

Which phase of the bacterial growth curve is characterized by equal rates of cell division and cell death?

Accepted Answer

Stationary phase

Question 7

Which of the following is a growth factor for bacteria?

Accepted Answer

Amino acids

Question 8

Which type of microorganism would you expect to find growing in refrigerated foods and why?

Accepted Answer

Psychrophiles, because they grow best at low temperatures.

Question 9

Which of the following statements about endospores is TRUE?

Accepted Answer

Endospores are resistant to heat and desiccation.

Question 10

A facultative anaerobe is best described as an organism that:

Accepted Answer

Can grow with or without oxygen.

Question 11

Which of the following is a real-world example of a disease caused by endospore-forming bacteria?

Accepted Answer

Anthrax

Question 12

Why does refrigeration not control the growth of Listeria monocytogenes?

Accepted Answer

It is a psychrotroph.

Question 13

Which of the following best describes the role of nitrogen fixation in microbial growth?

Accepted Answer

It converts nitrogen gas into usable organic molecules for all cells.

Question 14

Which of the following equations correctly represents the breakdown of hydrogen peroxide by catalase?

Accepted Answer

$$2H_2O_2 \rightarrow 2H_2O + O_2$

Question 15

Which of the following best explains how extreme halophiles resist plasmolysis?

Accepted Answer

They keep their cytoplasmic solute concentration high.

Question 16

During which phase of the bacterial growth curve are antibiotics most effective and why?

Accepted Answer

Log (exponential) phase, because cells are actively dividing.

Question 17

Which of the following is NOT a trace element required by bacteria?

Accepted Answer

Phosphorus

Question 18

What is the main advantage of biofilm formation for bacteria?

Accepted Answer

It provides protection from environmental stresses and antibiotics.

Question 19

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

Accepted Answer

A cell divides symmetrically to produce two genetically identical cells.

Microbial Growth and Nutrition: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard