6

Question 1

Five groups based on optimum growth temperature

Answer 1

Psychrophiles

Psychrotrophs

Mesophiles

Thermophiles

Hyperthermophiles

Question 2

Hypertonic environments (increased salt or sugar)
cause

Answer 2

plasmolysis

Question 3

Toxic Forms of Oxygen

Answer 3

Singlet oxygen:

Superoxide free radicals:

Peroxide anion:

Hydroxyl radical

Question 4

Microbial communities form
slime or hydrogels

Answer 4

Biofilms

Question 5

Bacteria communicate by chemicals via

Answer 5

quorum sensing

Question 6

Microbes introduced into medium

Answer 6

Inoculum:

Question 7

ex Complex media:

Answer 7

Nutrient broth

Nutrient agar

Blood agar

Question 8

Aerobic Bacteria Requiring High CO2

Answer 8

Capnophiles:

Question 9

Additives suppress
unwanted and encourage
desired microbes – e.g.
EMB, mannitol salt agar etc.

Answer 9

Selective medium:

Question 10

changed in recognizable
manner by some bacteria ⇒
Make it easy to distinguish
colonies of different
microbes – e.g. α and β
hemolysis on blood agar;

Answer 10

Differential medium:

Question 11

A population of cells arising from a
single cell or spore or from a group of attached
cells

Answer 11

Colony formation:

Question 12

Rapid cooling of pure culture in
suspension liquid to –50°to –95°C.

Answer 12

Deep-freezing:

Question 13

Frozen (–54° to –72°C)
and dehydrated in a vacuum. Good for many years.

Answer 13

Lyophilization

Question 14

time required for cell to divide

Answer 14

Generation time

Question 15

Phases of growth

Lag phase

Answer 15

Lag phase

Exponential or
logarithmic (log) phase

Stationary phase

Death phase (decline phase)

Question 16

method of choice for low counts

Answer 16

Filtration

Question 17

to measure turbidity

OD is function of cell number

Answer 17

Spectrophotometry

Question 18

Direct Methods

Answer 18

Plate counts

Filtration

MPN

Direct microscopic count

Question 19

Indirect Methods

Answer 19

Turbidity

Metabolic activity

Dry weight