Facultative anaerobes can live under either aerobic or anaerobic conditions. What metabolic pathways allow these organisms to continue to harvest energy from sugar molecules in the absence of oxygen?

“In the laboratory, a sterile inoculating loop is moved across the agar surface in a culture dish, thinning a sample and isolating individuals.” This statement describes which of the following?

a. Broth culture

b. Pour plate

c. Streak plate

d. Dilution plate

Superoxide dismutase _________.

a. Causes hydrogen peroxide to become toxic

b. Detoxifies superoxide radicals

c. Neutralizes singlet oxygen

d. Is missing in aerobes

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

a. Aerotolerant

b. Capnophiles

c. Facultative anaerobes

d. Fastidious

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

a. Cholesterol

b. Water

c. Vitamins

d. Heme

Organisms that preferentially may thrive in icy waters are described as _______.

a. Barophiles

b. Thermophiles

c. Mesophiles

d. Psychrophiles

Barophiles _______.

a. Cannot cause diseases in humans

b. Live at normal barometric pressure

c. Die if put under high pressure

d. Thrive in warm air

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

a. Obligate aerobe

b. Facultative aerobe

c. Obligate anaerobe

d. Facultative anaerobe

In a defined medium, ________.

a. The exact chemical composition of the medium is known

b. Agar is available for microbial nutrition

c. Blood may be included

d. Organic chemicals are excluded

Which of the following is most useful in representing population growth on a graph?

a. Logarithmic reproduction of the growth curve

b. A semilogarithmic graph using a log scale on the y-axis

c. An arithmetic graph of the lag phase followed by a logarithmic section for the log, stationary, and death phases

d. None of the above would best represent a population growth curve

Which of the following methods is best for counting fecal bacteria from a stream to determine the safety of the water for drinking?

a. Dry weight

b. Turbidity

c. Viable plate counts

d. Membrane filtration

A Coulter counter is a(n)_______.

a. Statistical estimation using 15 dilution tubes and a table of numbers to estimate the number of bacteria per milliliter

b. Indirect method of counting microorganisms

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

d. Device that directly counts microbes that are differentially stained with fluorescent dyes

Lyophilization can be described as ________.

a. Freeze-drying

b. Deep-freezing

c. Refrigeration

d. Pickling

Quorum sensing is _______.

a. The ability to respond to changes in population density

b. A characteristic allowing secretion of a matrix

c. Dependent on direct contact among cells

d. Associated with colonies in broth culture

All cells require a source of ___________ for redox reactions.

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

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

The lowest temperature at which a microbe continues to metabolize is called its ___________ .

Cells that shrink in hypertonic solutions such as saltwater are responding to ___________ pressure.

a. Optimum growth temperature

b. Maximum growth temperature

c. Minimum growth temperature

d. Metabolic threshold

Label each of these thioglycolate tubes to indicate the oxygen requirements of the microbes growing in them.

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

A student observes a researcher streaking a plate numerous times, flaming the loop between streaks. The researcher is likely using the ___________ method to isolate microorganisms.

If there are 47 cells in 1 μl of sewage, how many cells are there in a liter?

List three indirect methods of counting microbes.

List five direct methods of counting microbes.

High temperature affects the shape of particular molecules. How does this affect the life of a microbe?

Support or refute the following statement: Microbes cannot tolerate the low pH of the human stomach.

Explain quorum sensing, and describe how it is related to biofilm formation.

Why is agar used in microbiology?

What is the difference between complex media and defined media?