Question 1

Which of the following is a physical requirement for microbial growth?

Accepted Answer

Osmotic pressure

Question 2

A bacterium that grows best at 37°C and is commonly found in the human body is classified as a:

Accepted Answer

Mesophile

Question 3

Why does adding salt or sugar to food help preserve it from microbial spoilage?

Accepted Answer

It increases osmotic pressure, causing water to leave microbial cells.

Question 4

Which group of microbes is most likely to cause spoilage in refrigerated foods?

Accepted Answer

Psychrotrophs

Question 5

What is the main reason buffers are added to culture media in microbiology labs?

Accepted Answer

To maintain a stable pH as microbes produce acids

Question 6

Which of the following best explains why pickles and some cheeses resist spoilage?

Accepted Answer

They have a low pH that inhibits bacterial growth.

Question 7

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

Accepted Answer

Extreme halophile

Question 8

Which chemical element is most directly associated with the structure of ATP?

Accepted Answer

Phosphorus

Question 9

If a food item is cooled in a deep pot rather than a shallow pan, what is the main risk?

Accepted Answer

Microbes will have more time in their optimal growth range.

Question 10

Which of the following is a chemical requirement for microbial growth?

Accepted Answer

Carbon

Question 11

A microbe that can tolerate salty conditions but does not require high salt is called a:

Accepted Answer

Facultative halophile

Question 12

Which of the following best describes why food can still spoil in the refrigerator?

Accepted Answer

Psychrotrophs can grow slowly at low temperatures.

Question 13

Which group of microbes is most likely to be found near deep-sea hydrothermal vents?

Accepted Answer

Hyperthermophiles

Question 14

Which of the following is a reason why molds and yeasts can spoil acidic foods more easily than bacteria?

Accepted Answer

They tolerate a wider pH range.

Question 15

Which of the following is most likely to contain radioactive sulfur if added to a microbial culture?

Accepted Answer

Proteins

Question 16

Why might oxygen be helpful for one microbe but dangerous for another?

Accepted Answer

Some microbes use oxygen for energy, while others are harmed by toxic oxygen forms.

Question 17

Which of the following is an example of a trace element required by microbes?

Accepted Answer

Iron

Question 18

A fastidious organism is best described as one that:

Accepted Answer

Requires many organic growth factors.

Question 19

Which of the following best explains why jams and jellies are preserved by adding sugar?

Accepted Answer

Sugar increases osmotic pressure, drawing water out of microbial cells.

Question 20

Which of the following is NOT a physical requirement for microbial growth?

Accepted Answer

Nitrogen

Requirements for Microbial Growth: Physical and Chemical Factors

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