How do some cyanobacteria fix nitrogen while growing aerobically?

How do some cyanobacteria fix nitrogen while growing aerobically?

a. they don't because nitrogenase is destroyed by oxygen
b. by using special cells called heterocysts that protect the enzyme
c. by using cysts that protect the enzyme
d. they just do it, no special structures or mechanisms
e. they live symbiotically with other organisms that protect the enzyme


Answer: by using special cells called heterocysts that protect the enzyme

Some bacteria form environmentally resistant forms called __________.

Some bacteria form environmentally resistant forms called __________.

a. endospores
b. heterocysts
c. colonies
d. hyphae
e. actinomycetes


Answer: Endospores

Which of the following genera does NOT undergo differentiation?

Which of the following genera does NOT undergo differentiation?

a. Anabaena
b. Bacillus
c. Clostridium
d. Escherichia
e. Streptomyces


Answer: Escherichia

During biofilm formation, as more and more cells bind to the surface, they begin sending signals to each other in a process called

During biofilm formation, as more and more cells bind to the surface, they begin sending signals to each other in a process called

a. quorum sensing
b. homoserine lactone
c. siderophores
d. polysaccharides
e. symbiosis


Answer: Quorum sensing

Which of the following is true of all biofilms?

Which of the following is true of all biofilms?

a. They only contain a single species.
b. The EPS may be protein or polysaccharide.
c. Cells in the biofilm are dormant until the bacteria leave the biofilm.
d. The EPS is secreted by the bacteria.
e. It is a continuous monolayer surface deposit.


Answer: The EPS is secreted by the bacteria

Eukaryotic microorganisms enter the __________ phase at much lower cell numbers than bacteria simply because they are bigger than bacteria.

Eukaryotic microorganisms enter the __________ phase at much lower cell numbers than bacteria simply because they are bigger than bacteria.

a. lag
b. exponential
c. stationary
d. death
e. log


Answer: Stationary

You are measuring growth in a bacterial culture. The number of viable cells remains constant, and when you check the medium, you find that the carbon source has been used up. What phase of growth is the culture in?

You are measuring growth in a bacterial culture. The number of viable cells remains constant, and when you check the medium, you find that the carbon source has been used up. What phase of growth is the culture in?

a. lag phase
b. early log phase
c. late log phase
d. stationary phase
e. death phase


Answer: Stationary phase

E. coli adjusts to the stationary phase by doing all of the following except:

E. coli adjusts to the stationary phase by doing all of the following except:

a. decrease its size
b. synthesize enzymes to handle oxygen radicals
c. synthesize proteins to protect DNA and proteins
d. increase peptidoglycan cross-linking
e. form spores


Answer: Form spores

Quorum sensing begins during which growth stage?

Quorum sensing begins during which growth stage?

a. lag
b. early log
c. late log
d. stationary
e. death


Answer: Late log

During which stage of bacterial growth is the culture growing exponentially?

During which stage of bacterial growth is the culture growing exponentially?

a. lag
b. early log
c. late log
d. stationary
e. death


Answer: Early log

In which case would the shortest lag period most likely be observed?

In which case would the shortest lag period most likely be observed?

a. transfer from complex medium to fresh complex medium
b. transfer from complex medium to minimal medium
c. transfer to a different temperature
d. transfer to a different pH
e. transfer to a different salt concentration


Answer: Transfer from complex medium to fresh complex medium

The time between inoculation and the beginning of growth is usually called the:

The time between inoculation and the beginning of growth is usually called the:

a. lag phase
b. early log phase
c. late log phase
d. stationary phase
e. death phase


Answer: Lag phase

If an organism produces seven offspring per generation, which of the following would express the rate of increase in population, where n corresponds to the number of generations?

If an organism produces seven offspring per generation, which of the following would express the rate of increase in population, where n corresponds to the number of generations?

a. 2n
b. n2
c. 7n
d. n7
e. 2n7


Answer: 7^n

The time interval required for the formation of two cells from one is called the

The time interval required for the formation of two cells from one is called the

a. generation time
b. growth time
c. growth rate
d. exponential


Answer: Generation time

A cafeteria worker who fails to wash his hands thoroughly and fails to wear gloves inoculates a quiche with 4 E. coli when he uses his finger to test whether it is done. By the time you purchase the quiche, there are 128 E. coli cells in it. How many generations did the cells go through?

A cafeteria worker who fails to wash his hands thoroughly and fails to wear gloves inoculates a quiche with 4 E. coli when he uses his finger to test whether it is done. By the time you purchase the quiche, there are 128 E. coli cells in it. How many generations did the cells go through?

a. 4
b. 5
c. 8
d. 32
e. 64


Answer: 5

Growth of most microorganisms occurs by:

Growth of most microorganisms occurs by:

a. budding
b. binary fission
c. replication
d. conjugation
e. transformation


Answer: Binary fission

____ cells are free-living organisms that grow and multiply on their own.

____ cells are free-living organisms that grow and multiply on their own.

a. Endospores
b. Parasites
c. Symbionts
d. Planktonic
e. Heterocyst


Answer: Planktonic

What type of growth pattern is represented here: 5 × 103; 1 × 104; 2 × 104; 4 × 104; 8 × 104?

What type of growth pattern is represented here: 5 × 103; 1 × 104; 2 × 104; 4 × 104; 8 × 104?

a. linear
b. exponential
c. lag
d. generation
e. semilogarithmic


Answer: Linear

When the population doubles during each given unit of time the growth is

When the population doubles during each given unit of time the growth is

a. linear
b. semilogarithmic
c. exponential
d. geometric
e. arithmetic


Answer: exponential

A problem with __________ of cell number is that dead cells also scatter light.

A problem with __________ of cell number is that dead cells also scatter light.

a. direct microscopic counts
b. viable counts
c. spread plate counts
d. pour plate counts
e. optical density measurements


Answer: Optical density measures