Deck 4: Bacterial Culture, Growth, and Development

Question 1

A(n) ________ cell loses membrane integrity and cannot carry out the simple transport functions needed to sustain growth.

A) depolarized
B) endospore
C) planktonic
D) heterocyst
E) dormant

Answer 1

A

Question 2

Which of the following proteins represents a coupled transport system where two molecules travel in the same direction?

A) aquaporin
B) symport
C) antiport
D) porin
E) diffusion transporters

Answer 2

B

Question 3

The majority of nitrogen in soil and marine environments is fixed by

A) free-living bacteria and archaea.
B) symbionts.
C) E. coli.
D) biofilm organisms.
E) UV light.

Answer 3

A

Question 4

Which of the following are specific nutrients NOT required by other species?

A) macronutrients
B) micronutrients
C) growth factors
D) trace elements
E) essential nutrients

Question 5

When the intracellular iron concentration is low, iron-scavenging molecules called ________ are produced.

A) siderophores
B) endospores
C) heterocysts
D) mycelia
E) quorum sensors

Question 6

Why do some members of a biofilm community live deep within the biofilm?

A) They are not flagellated.
B) They produce fewer exopolysaccharides.
C) They were the first organisms to initiate attachment.
D) Antibiotics do not penetrate deep into biofilms.
E) Oxygen does not penetrate deep into biofilms.

Question 7

A(n) ________ is an organism that lives in an intimate association with a second organism.

A) commensal
B) parasite
C) heterocyst
D) endospore
E) symbiont

Question 8

Quorum sensing is triggered in biofilms when

A) they form microcolonies.
B) they are dispersing.
C) antibiotics are applied to them.
D) the population reaches a certain number.
E) cells attach to a surface.

Question 9

Which of the following prokaryotic transport systems does NOT require the use of cellular energy to bring compounds into the cells?

A) facilitated diffusion
B) ABC transport
C) siderophores
D) group translocation
E) endocytosis

Question 10

There is a constant struggle to survive in natural habitats because of a lack of

A) food.
B) sunlight.
C) water.
D) oxygen.
E) minerals.

Question 11

The primary goal of biofilms is thought to be

A) microbial communication.
B) cell differentiation.
C) to stay where food is abundant.
D) to cause infection.
E) environmental degradation.

Question 12

Which of the following are responsible for the CO₂-fixation component of the carbon cycle?

A) heterotrophs
B) symbionts
C) autotrophs
D) chemotrophs
E) organotrophs

Question 13

Which of the following is NOT true about the substrate-binding protein (SBP) of the ABC transport system?

A) It floats in the periplasm of Gram-negative cells.
B) It is tethered to the cell surface in Gram-positive cells.
C) It binds to the periplasmic face of the channel and releases the solute.
D) It snags the appropriate solute.
E) It is required for both the uptake and efflux systems.

Question 14

Which of the following occurs when a sessile biofilm (or a part of it) begins to starve or experiences oxygen depletion?

A) attachment
B) quorum sensing
C) EPS production
D) dispersal
E) biofilm maturation

Question 15

Left on their own, heterotrophs would deplete the world of ________ sources and starve to death.

A) usable nitrogen
B) organic carbon
C) water
D) energy
E) oxygen

Question 16

Which of the following can consume glucose and, in the absence of oxygen, break it down into ethanol and carbon dioxide gas?

A) E. coli
B) phototrophs
C) yeast
D) archaea
E) nitrogen fixers

Question 17

All of Earth's life-forms are based on

A) hydrogen.
B) nitrogen.
C) oxygen.
D) carbon.
E) phosphorus.

Question 18

All known microorganisms have a set of genes coding for ________, whose RNA sequences are highly conserved across the phylogenetic tree.

A) ribosomes
B) chloroplasts
C) enzymes
D) cell membranes
E) cell walls

Question 19

Which of the following is a micronutrient?

A) carbon
B) nitrogen
C) sulfur
D) calcium
E) zinc

Question 20

The most common form of chemical energy is contained in the high-energy phosphate bonds of

A) water.
B) glucose.
C) ATP.
D) CO₂.
E) NADH.

Question 21

Siderophore-iron complexes enter cells with the help of

A) porins.
B) diffusion.
C) aquaporins.
D) ABC transporters.
E) efflux pumps.

Question 22

Bacteria divide at a constant time interval called the

A) generation time.
B) growth time.
C) growth rate.
D) exponential rate.
E) log phase.

Question 23

Quorum sensing begins during which growth stage?

A) lag
B) early log
C) late log
D) stationary
E) death

Question 24

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

A) linear.
B) semilogarithmic.
C) exponential.
D) geometric.
E) arithmetic.

Question 25

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

Question 26

The most widely used solidifying agent is ________, which is derived from seaweed.

A) agar
B) gelatin
C) starch
D) cellulose
E) glycogen

Question 27

Which of the following statements is FALSE about the E. coli phosphotransferase system (PTS)?

A) Enzyme II components are specific to the substrates being transported.
B) The substrate is phosphorylated during transport by PTS, making it different from the external substrate; thus, the substrate always travels down its concentration gradient.
C) The phosphate group transferred to the sugar comes from phosphoenolpyruvate (PEP).
D) The PTS transport requires energy in the form of ATP.
E) The system has a modular design that accommodates different substrates.

Question 28

The figure below represents what type of differentiation?

A) heterocyst formation
B) budding
C) sporulation
D) fruiting body formation
E) filamentation

Question 29

You have isolated a bacterium from the rumen of a cow and wish to know how it transports glucose into the cell. You perform an experiment that shows uptake of radioactively labeled glucose is equal when the organism is grown in media in the presence and absence of inhibitors of energy production. What is the mechanism of glucose transport in this cell?

A) group translocation
B) diffusion
C) facilitated diffusion
D) active transport
E) endocytosis

Question 30

Which forms are NOT made by Streptomyces?

A) hyphae
B) germinating spores
C) filaments
D) endospores
E) mycelia

Question 31

Growth of most microorganisms occurs by

A) budding.
B) binary fission.
C) replication.
D) conjugation.
E) transformation.

Question 32

The best method to isolate single colonies is the ________ plate, and the best method to count colonies is the ________ plate.

A) streak; pour
B) pour; streak
C) defined; complex
D) complex; defined
E) spread; streak

Question 33

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

A) lag phase
B) log phase
C) growth phase
D) stationary phase
E) death phase

Question 34

Cyanobacterial heterocysts function to fix atmospheric

A) hydrogen sulfide.
B) ammonia.
C) oxygen.
D) carbon dioxide.
E) nitrogen.

Question 35

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

Question 36

Which of the following intercalates between DNA bases, causing dead cells to stain red under a fluorescence scope?

A) propidium iodide
B) syto-9
C) bile salt
D) crystal violet
E) safranin

Question 37

Which of the following is the best technique for counting only viable cells?

A) direct microscopic count
B) spread plate
C) spectrophotometer
D) chemostat
E) dry weight measurements

Question 38

The time between inoculation and the beginning of growth is usually called the ________ phase.

A) lag
B) early log
C) late log
D) stationary
E) death

Question 39

Which term refers to the condition in which a culture growth covers the entire agar surface?

A) dilution streaking
B) spread plate
C) confluent
D) microcolony
E) colony

Question 40

Metabolism of a microbe is best examined by growing the organism in a

A) defined medium.
B) complex medium.
C) spread plate.
D) pour plate.
E) cell culture.

Question 41

How do scientists know of the existence of "unculturable" organisms?

Question 42

What type of medium and conditions would you need to have in order to select for photoautotrophs?

Question 43

What is the classic approach for finding new antibiotics?

A) screening animals for secreted antimicrobial compounds
B) harvesting them from individuals with immunity
C) screening bacteria and fungi for secreted antimicrobial compounds
D) harvesting them from sick individuals
E) synthesizing them in the laboratory

Question 44

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 sensing.
C) siderophore-iron acquisition.
D) polysaccharides uptake.
E) density sensing.

Question 45

Some bacteria form environmentally resistant dormant forms called

A) endospores.
B) heterocysts.
C) colonies.
D) hyphae.
E) actinomycetes.

Question 46

Which of the following genera does NOT undergo differentiation?

A) Anabaena
B) Bacillus
C) Clostridium
D) Escherichia
E) Streptomyces

Question 47

Compare and contrast complex media, synthetic media, and enriched media.

Question 48

Compare and contrast the ABC transporters and group translocation in terms of energy requirements and concentration gradients.

Question 49

Define the terms "viable" and "viable but unculturable." Why are so many environmental organisms believed to be viable but unculturable?

Question 50

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. In which phase of growth is the culture?

A) lag
B) early log
C) late log
D) stationary
E) death

Question 51

MacConkey medium contains bile salts, crystal violet, lactose, and the pH indicator neutral red. Some organisms can ferment lactose, producing acids as a by-product. Is this medium likely to be selective and/or differential? Explain.

Question 52

When studying the metabolism of an organism, why is it better to grow organisms in a defined synthetic medium instead of a complex medium?

Question 53

Why is iron so often a limiting nutrient, when it seems to be so abundant in the environment, and how can organisms overcome this problem?

Question 54

How do some cyanobacteria fix nitrogen while growing aerobically?

A) They do not, because nitrogenase is destroyed by oxygen.
B) They use special cells called heterocysts that protect the enzyme.
C) They use spores that protect the enzyme.
D) They do it using no special structures or mechanisms.
E) They live symbiotically with other organisms that protect the enzyme.

Question 55

The shortest lag period would most likely be observed in the transfer

A) from complex medium to fresh complex medium.
B) from complex medium to minimal medium.
C) to a lower temperature.
D) to a different pH.
E) to a different salt concentration.

Question 56

In order to grow unculturable environmental microbes, Kim Lewis and colleagues derived the iChip. What is the purpose of this device?

A) Antibiotics from the environment could pass into the chamber.
B) Gram-positive organisms could not pass the semipermeable membrane.
C) The semipermeable membranes let environmental organisms into the agar.
D) Organisms from the environment grew in the chamber.
E) Nutrients and growth factors made by organisms in the soil diffused into the chamber.

Question 57

Why can't most organisms use the nitrogen gas that is so prevalent in the atmosphere? How do these organisms acquire a usable form of nitrogen?

Question 58

Which of the following is true of all biofilms?

A) They only contain a single species.
B) The EPS are composed of proteins.
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.

Question 59

A cafeteria worker who fails to wash his hands thoroughly and fails to wear gloves inoculates a quiche with 4 E. coli cells 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

Question 60

Compare and contrast the difference between electrogenic and electroneutral coupled transport and give an example of each.

Question 61

Why does binary fission result in an exponential and not a linear growth rate?

Question 62

Discuss some disadvantages of viable counts of microorganisms.

Question 63

Using the figure below, explain the function of stages 2 and 3 in biofilm development and how they affect biofilm growth, function, and treatment.

Question 64

Describe the differences between batch culture and growth in a chemostat. What are the advantages of a chemostat?

Question 65

How does Anabaena overcome the challenge of performing both photosynthesis and nitrogen fixation?

Question 66

During the stationary phase, E. coli reprograms itself. What does it do to protect itself?

Question 67

What are some specific problems that biofilms can cause in the medical field, and why are they so difficult to prevent and destroy?

Question 68

If you determined the number of cells in a sample using viable plate counts and optical density measurements, why would the results from the two methods be so different?

Question 69

Why would an organism go through the process of sporulation? How might endospores cause problems in the food industry?

Question 70

Why does a microbe's growth rate in its natural environment vary greatly from that in the laboratory? Give at least two reasons for this.