Practice Test Exam 3 OPTION 1

A mesophillic bacteria would be able to

grow at human body temperatures

A sterilizer that employs superheated steam under pressure

autoclave

T/F During the lag phase of microbial growth, the cells are metabolically inactive

false

The killing of spore forming bacteria by alternatively heating to kill the vegetative cells and incubating to allow the germination of spores into vegetative cells that are then killed by another heating cycle

tyndalization

The length of time it takes for a population to double in number

doubling time

An organism that can grow in sulfuric acid is said to be

acidophilic

How would you sterilize a plastic dish that can NOT be heated

ionizing radiation

The lowest temperature at which a microbial population is killed in a specific period of time

thermal death point

Which is the most rapid way to achieve sterilization

direct flame

Bacteria reproduce by the process

binary fission

A period of two hours at 160'C is required for killing bacteria

in a hot air oven

Removal of microorganisms from liquids and gases by passing the material through a substance with pore sizes designed not to allow microorganisms to penetrate

filtration

Organisms that grow at high temperatures

thermophiles

Bacteria that can grow in the absence of oxygen but grow better in its presence

facultative

Organisms that have a wide range of growth temperatures are said to be

eurythermal

An approximation of the number of living organisms per unit volume based on the formation of colonies on a solid growth media

viable cell count

Objects that are devoid of any form of life

sterile

An example of an obligate anaerobe

Bacteriodes fragilis

Organisms that ignore oxygen and grow equally well in its presence or absence

aerotolerant anaerobe

Organisms that require high salt concentrations in order to grow

halophilic

A culture in a closed vessel with a single batch of medium to which no fresh medium is added and from which no waste products are removed

batch culture

Which of the following is NOT a form of ionizing radiation

ultraviolet light