Ch 4 Environmental Limitations

Question 1

True or False: Microbes have the slowest growth rates known of organisms

Answer 1

False, fastest and slowest

Question 2

What are the normal growth conditions of microbes?

Answer 2

20-40 C, sea level, Neutral pH, .9% salt

Question 3

What is a microbe that lives outside of normal growth conditions?

Answer 3

Extremophile

Question 4

What is a microbes survival in an environmental habitat based on?

Answer 4

Its protein’s and structure’s ability to tolerate the physical conditions of the environment

Question 5

What is a halophile?

Answer 5

Growth in high salt

Question 6

What is an alkaliphile?

Answer 6

Growth above pH: 9

Question 7

What is a barophile?

Answer 7

Growth at high pressure

Question 8

True or False: Bacteria’s cell temperature does not match that of its environment

Answer 8

False

Question 9

When do microbes have higher growth rates?

Answer 9

At higher temperatures

Question 10

The growth rate _______ for every ___ rise in temperature

Answer 10

doubles, 10 C

Question 11

True or False: Extremophiles have the fastest growth rate

Answer 11

True

Question 12

What is the heat-shock response?

Answer 12

Rapid temperature changes during growth activates a stress response

Question 13

True or False: Barophiles are also psychrophiles

Answer 13

True, bc they inhabit the ocean floor

Question 14

What is water activity?

Answer 14

Measure of how much water is available for use

Question 15

What is the most water activity bacteria need?

Answer 15

> .91

Question 16

What is the most water activity fungi need?

Answer 16

> .86

Question 17

What are aquaporins?

Answer 17

Membrane channel proteins that allow water to traverse the membrane faster than diffusion does

Question 18

What ions do halophiles use to achieve a low internal concentration?

Answer 18

Na+ goes out and K+ comes in (ion pump)

Question 19

What can weak acids do once they pass through membranes?

Answer 19

Disrupt cell pH homeostasis, kill cells, used to preserve foods