BMS 127 Ch. 6 Microbial Nutrition & Growth

Question 0

Which term best describes an organism that cannot exist in the presence of oxygen?

Answer 0

obligate anaerobe

Question 1

Which of the following can grow in a Petri plate on a laboratory table?

a. an anaerobe
b. a colony on an agar surface
c. viruses on an agar surface
d. barophiles

Answer 1

b. a colony on an agar surface

Question 2

What does superoxide dimutase do?

Answer 2

detoxifies superoxide radicals

Question 3

What is the most reactive of the four toxic forms of oxygen?

Answer 3

the hydroxyl radical

Question 4

What are the four toxic forms of oxygen?

Answer 4

the hydroxyl radical, the peroxide anion, the superoxide radical and singlet oxygen

Question 5

Microaerophiles that grow best with a high concentration of carbon dioxide in addition to low level of oxygen are called ______.

Answer 5

capnophiles

Question 6

Which of the following is not a growth factor for various microbes?

a. cholesterol
b. water
c. vitamins
d. heme

Answer 6

b. water

Question 7

What are organisms that preferentially may thrive in icy waters described as?

Answer 7

psychrophiles

Question 8

Can barophiles cause disease in humans?

Answer 8

no

Question 9

What is the most common way of isolating single colonies on an agar plate in a lab?

Answer 9

streak plate

Question 10

In a _______ medium, the exact chemical composition of the medium is known.

Answer 10

defined

Question 11

What type of graph is most useful in representing population growth on a map?

Answer 11

a semilogarithmic graph using a log scale on the y-axis

Question 12

What is the best method for counting fecal bacteria from a stream to determine the safety of the water for drinking?

Answer 12

membrane filtration

Question 13

What is a Coulter counter?

Answer 13

a device that directly counts microbes as they pass through a tube in front of an electronic detector

Question 14

What is lyophilization?

Answer 14

freeze-drying

Question 15

What is the bacterial ability to sense and respond to changes in population density called?

Answer 15

quorum sensing

Question 16

All cells require sources of ______, _______ and _______.

Answer 16

carbon; energy; electrons

Question 17

A toxic form of oxygen, _______ oxygen, is molecular oxygen with electrons that have been boosted to a higher energy level.

Answer 17

singlet

Question 18

All cells recycle the essential element _______ from amino acids and nucleotides.

Answer 18

nitrogen

Question 19

_______ are small organic molecules that are required in minute amounts for metabolism.

Answer 19

Growth factors

Question 20

What is the lowest temperature at which a microbe continues to metabolize?

Answer 20

minimum growth temperature

Question 21

Cells that shrink in a hypertonic solution such as saltwater are responding to _________ pressure.

Answer 21

osmotic

Question 22

Obligate _______ exist in salt ponds because of their ability to withstand high osmotic pressure.

Answer 22

halophiles

Question 23

_______ pigments protect many phototrophic organisms from photochemically produced singlet oxygen.

Answer 23

Carotenoid

Question 24

Microbes that reduce N2 to NH3 engage in ________.

Answer 24

nitrogen fixation