Exam 3 Micro

Which of the following is a method of measuring microbial growth?

Colony-forming units (CFUs)

Antibiotic

A substance that can inhibit or kill microorganisms

Pathogen

An organism capable of causing disease

Aseptic technique

A set of practices used to prevent contamination of a sterile environment

Biofilm

A community of microorganisms attached to a surface

Which of the following is a method of microbial control on inanimate objects?

Chemical disinfection

Which of the following uses glucose for carbon and energy?

chemoheterotroph

How would a noncompetitive inhibitor interfere with a reaction involving the enzyme shown in the figure above?

It would bind to b.

Bacterial growth refers to an increase in the numbers of cells in a bacterial culture.

True

Which enzyme catalyzes 2H2O2 → 2H2O + O2?

catalase

Autoclaving is the most effective method of moist heat sterilization.

True

Most bacteria grow best at pH

7.

The term aerotolerant anaerobe refers to an organism that

does not use oxygen but tolerates it.

How is beef jerky preserved from microbial growth?

desiccation

Both respiration and photosynthesis require the use of an electron transport chain.

True

Which disinfectant acts by disrupting the plasma membrane?

bisphenols

The figure above shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture. In the figure, which section (or sections) shows a growth phase where the number of cells dying equals the number of cells dividing?

c

Increasing the temperature of a reaction will do all of the following EXCEPT

increase the activation energy

Moist heat destroys organisms by denaturing proteins.

True

A disk-diffusion test using Staphylococcus gave the following results: Which disinfectant is most effective against Staphylococcus?

C

What happens to pyruvic acid in aerobic respiration?

It is converted into acetyl CoA.

Where is ATP produced in the figure?

e

Which tube shows microaerophile growth?

e

Glycolysis is used in both respiration and fermentation.

True

The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature.

true

The following data show growth of two bacteria on different media: The data in table indicates that S. aureus is a(n)

facultative halophile.

In the figure above, the structure labeled "1" is

a plasma membrane.

Which of the following is the best definition of generation time?

the length of time needed for a cell to divide

From the list below, which is NOT produced during the Krebs cycle?

NADPH

Carbon fixation occurs during the light-independent phase of photosynthesis.

true

Salts and sugars work to preserve foods by creating a

hypertonic environment.

Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes?

refrigeration

Most bacteria reproduce by

binary fission

Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization.

false

An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n)

disinfectant

Which of the following pairs of terms is mismatched?

bacteriostatic - kills vegetative bacterial cells

Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt?

facultative halophiles

Which of the following pairs of microbe classification terms and optimal growth temperatures is mismatched?

thermophile - growth at 37°C

The following data was obtained by incubating gram-positive bacteria in nutrient medium + disinfectant for 24 hours, then transferring one loopful to nutrient medium (subculturing). (+ = growth; - = no growth): Using the table above, which disinfectant is the most effective at stopping bacterial growth?

doom

Most pathogenic bacteria are thermophiles.

false

Which of the following compounds is NOT an enzyme? coenzyme A

Cyanobacteria are a type of

photoautotroph

Desiccation is a reliable form of sterilization.

false

Most fungi grow best at pH

5

Once an enzyme has converted substrates into products, the active site reverts back to its original form.

true

A bacterium that only possesses the ability to ferment obtains energy

by glycolysis only

A culture medium consisting of agar, peptone, and beef heart (blood) is a

complex medium

Which concentration of ethanol is the most effective bactericide?

70 percent

Flagella

cellular locomotion

pili

attachment to surfaces

Capsule

Protection from immune response

Endospore

Survival in harsh environments

Which of the following uses CO2 for carbon and H2 for energy?

chemoautotroph