Environmental Factors Affecting Microbial Growth

Question 1

Physical cleaning with soaps / detergents is an example of ______

Answer 1

Decontamination

Question 2

______ is the lowest level of pathogen control

Answer 2

Decontamination

Question 3

Liquid chemical agents are examples of ______

Answer 3

Disinfection

Question 4

Disinfection typically does not kill …

Answer 4

Large numbers of endospores

Question 5

Define antiseptic

Answer 5

Elimination of pathogens on living tissue

Question 6

Define sterilization

Answer 6

Complete elimination of viable organisms including endospores

Question 7

Incineration, moist heat, and ionizing radiation are examples of ______

Answer 7

Sterilization

Question 8

______ is the highest level of pathogen control

Answer 8

Sterilization

Question 9

Define minimum growth temperature

Answer 9

Lowest temperature at which an organism is able to metabolize

Question 10

Define maximum growth temperature

Answer 10

Highest temperature at which an organism is able to metabolize

Question 11

Define optimum growth temperature

Answer 11

Temperature at which an organism’s metabolic activities produce the highest growth rate

Question 12

What are an organism’s cardinal temperatures?

Answer 12

Minimum, maximum, and optimum growth temperatures

Question 13

What happens to biochemistry at temperatures above the Tm(max)?

Answer 13

Enzymes begin to denature

Question 14

What happens to biochemistry at temperatures below the Tm(min)?

Answer 14

Enzyme activity is suspended

Question 15

What happens due to membrane dynamics as Tm increases?

Answer 15

Membrane lipids become destabilized

Question 16

What happens due to membrane dynamics as Tm decreases?

Answer 16

Transport of nutrients decreases

Question 17

As Tm decreases, the plasma membrane …

Answer 17

Becomes less fluid

Question 18

At what temperatures do psychrophiles grow best?

Answer 18

Below 20°C

Question 19

Some ______ cause food spoilage at refrigerator temperature

Answer 19

Psychrophiles

Question 20

Why don’t psychrophiles cause disease in humans?

Answer 20

They cannot survive at body temperature

Question 21

In what habitats are psychrophiles common? (3)

Answer 21

• Ocean
• Arctic
• Antarctic

Question 22

At what temperatures do psychrotrophs grow best?

Answer 22

0°C - 30°C

Question 23

Most human pathogens and normal microbiota of the human body are ______

Answer 23

Mesophiles

Question 24

At what temperatures do thermophiles grow best?

Answer 24

40°C - 45°C

Question 25

At what temperatures do hyperthermophiles grow best?

Answer 25

Above 80°C

Question 26

What is pH?

Answer 26

The concentration of hydrogen ions (H+) in a solution

Question 27

pH below 7.0 = ______

Answer 27

Acidic

Question 28

pH of 7.0 = ______

Answer 28

Neutral

Question 29

pH above 7.0 = ______

Answer 29

Basic (alkaline)

Question 30

Explain why organisms are sensitive to pH changes

Answer 30

Hydrogen ions interfere with the bonding of proteins and nucleic acids

Question 31

What effect does pH have upon biological molecules?

Answer 31

Denaturation of three-dimensional structure

Question 32

pH changes and denaturation can be ______ to the cell

Answer 32

Inhibitory / lethal

Question 33

Neutrophils include what types of organisms? (3)

Answer 33

• Bacteria
• Protozoa
• Pathogens

Question 34

At what pH do neutrophils grow best?

Answer 34

6.5 - 7.5

Question 35

Acidophils include what types of organisms?

Answer 35

Most fungi

Question 36

At what pH do acidophiles grow best?

Answer 36

Below 5.5

Question 37

At what pH do alkaliphiles grow best?

Answer 37

Above 8.5

Question 38

Alkaliphiles grow in what types of environments? (2)

Answer 38

• Soil
• Water