Chapter 6

Question 0

What is Agar?

Answer 0

Complex polysacch derived from a marine alga and used as solidifying agent in culture media

Question 1

Most bacterial cells grow by what asexual process?

Answer 1

Binary fission

Question 2

What is a toxic anion (O2-) with an unpaired electron?

Answer 2

Superoxide radical

Question 3

What’s a biofilm?

Answer 3

A microbial community that usually forms as a slimy later on a surface

Question 4

What is the ability of bacteria to communicate and coordinate via signaling molecules called?

Answer 4

Quorum sensing

Question 5

What type of organism can grow WITH OR WITHOUT molecular oxygen (O2)?

Answer 5

Facultative anaerobe

Question 6

What’s a serial dilution?

Answer 6

Process of diluting a sample several times

Question 7

What’s a peroxide anion?

Answer 7

An oxygen anion consisting of two atoms of oxygen

Question 8

What is generation time?

Answer 8

The time required for a cell or population to double in number

Question 9

What is an enzyme that breaks down hydrogen peroxide (2H2O2 : 2H2O + O2 )

Answer 9

Catalase

Question 10

What is an enzyme that destroys superoxide ?

Answer 10

Superoxide dismutase (SOD)

Question 11

Organism that DOES NOT use O2 and is killed in the presence of it

Answer 11

Obligate Anaerobe

Question 12

Visible bacterial colonies on solid media

Answer 12

Colony forming units (CFU)

Question 13

What is a visible mass of microbial cells arising from one cell or from a group of the same microbes?

Answer 13

Colony

Question 14

Organism that DOES NOT use O2 but is not affected by its presence

Answer 14

Aerotolerant anaerobe

Question 15

Organism that requires molecular oxygen (O2)

Answer 15

Obligate aerobe

Question 16

What’s the conversion of nitrogen from the atmosphere into ammonia called?

Answer 16

Nitrogen fixation

Question 17

Organism that grows best in an environment with less molecular oxygen (O2) than found in air

Answer 17

Microaerophile

Question 18

Microorganism that grows best at relatively high CO2 concentrations

Answer 18

Capnophile

Question 19

Bacteria that spoil food in fridge are probably ?

Answer 19

Psychrotrophs

Question 20

If 52 bacterial colonies grow on a nutrient agar plate inoculated with 1 ml of a 1:1000 dilution of hamburger , how many bacteria are in original sample?

Answer 20

52,000

Question 21

Microbial growth is

Answer 21

The number of cells, NOT the size of the cells. Microbes that are growing are increasing in number, accumulating into colonies

Question 22

How do bacteria survive in nutrient poor environments

Answer 22

By forming biofilms. Biofilms are frequently sources of health care associated infections

Question 23

Requirements for microbial growth are?

Answer 23

1. Physical (temperature, pH, osmotic pressure) 2. Chemical (sources of carbon, nitrogen, sulfur, phosphorus, oxygen, trace elements, and organic growth factors)

Question 24

Psychrophiles

Answer 24

Cold loving microbes

Question 25

Mesophiles

Answer 25

Moderate temperature loving microbes

Question 26

Thermophiles

Answer 26

Heat loving microbes

Question 27

What causes the rapid growth decline outside of optimum growth temperature

Answer 27

Bc the high temperature has presumably inactivated necessary enzymatic systems of the cell

Question 28

Optimum temperature for many pathogenic bacteria

Answer 28

37 degrees Celcius, bc organisms have adapted to live in the bodies of their host, and their optimum temperatures are close to that of the host

Question 29

Optimum growth temperature of 25-40° C

Answer 29

Mesophiles (most common type of microbe)

Question 30

What type of media is designed to suppress growth of unwanted bacteria and encourage the growth of the desired microbes?

Answer 30

Selective media

Question 31

Sequence of cell division

Answer 31

1. Cell elongates and DNA is replicated 2. Cell wall and plasma membrane begin to constrict 3. Cross-wall forms, completely separating the two DNA copies 4. Cells separate

Question 32

T/F A chemically defined medium is any material prepared for the growth of bacteria in a laboratory

Answer 32

True

Question 33

Shrinking of the cells cytoplasm in response to osmotic loss of water is called

Answer 33

Plasmolysis

Question 34

Shrinking of the cells cytoplasm in response to osmotic loss of water is called

Answer 34

Plasmolysis

Question 35

What (2) pathogens are considered acidophiles?

Answer 35

H. pylori = (bad) ph1 --\> stomach ulcers Lactobacillus = (good) ph 3-5 --\> maintains vaginal pH

Question 36

Hypertonic solns cause \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_?

Answer 36

Plasmolysis

Question 37

T/F S. epidermidid is a facultative halophile?

Answer 37

True

Question 38

What does a "fastiduous" organism require?

Answer 38

Many different components in its culture media

Question 39

What does (MSA) Mannitol Salt Agar select for?

Answer 39

facultative halophiles

Question 40

T/F A facultative halophile will grow on both a TSA and an MSA plate?

Answer 40

True

Question 41

What is the purpose of using Differential Media?

Answer 41

to specifically identify an organism based upon a certain characteristic

Question 42

Blood Agar is an example of ______________ media.

Answer 42

Differential

Question 43

σ-hemolysis = _____ hemolysis ß-hemolysis = ______ hemolysis ý-hemolysis = ______ hemolysis

Answer 43

partial complete no

Question 44

Eosis Methylene Blue (EMB) agar selects for _________ microbes and differentiates b/tween __________ fermenters.

Answer 44

Gram - lactose/sucrose

Question 45

Which of the following is MSA? Selective Differential Both Neither

Answer 45

Both | (selects for salt)

Question 46

Reducing media is used to culture for _____________ anaerobes becasue it contains chemicals that deplete O2 in the culture medium.

Answer 46

obligate

Question 47

2ⁿ describes the number of _______ in what type of division?

Answer 47

doublings binary fission