Deck 4: Bacterial Culture, Growth, and Development

Question 1

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

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

Answer 1

A

Question 2

__________ are responsible for the carbon-fixation component of the carbon cycle.

A) Heterotrophs
B) Symbionts
C) Autotrophs
D) Chemotrophs
E) Organotrophs

Answer 2

C

Question 3

__________ are specific nutrients that are NOT required by all cells.

A) Macronutrients
B) Micronutrients
C) Growth factors
D) Trace elements
E) Essential nutrients

Answer 3

C

Question 4

A(n) __________ cell loses membrane integrity and cannot carry out the simple transport functions needed to support life.

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

Question 5

In the laboratory, Escherichia coli can divide into two cells every:

A) 1-5 minutes
B) 5-10 minutes
C) 20-30 minutes
D) 50-60 minutes
E) 2 hours

Question 6

Which form of transport occurs only in eukaryotes?

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

Question 7

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

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

Question 8

By themselves, heterotrophs would deplete the world of __________ sources and starve to death.

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

Question 9

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

Question 10

A microbial population explosion results from the sudden availability of:

A) water
B) oxygen
C) food
D) sunlight
E) prey

Question 11

__________ can consume glucose and, in the absence of oxygen, can break it down into ethanol and carbon dioxide gas.

A) E. coli
B) Phototrophs
C) Yeast
D) Archaea
E) Bacteria

Question 12

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

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

Question 13

Microorganisms constantly struggle to survive in natural habitats because of the competition for:

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

Question 14

All of Earth's life-forms are based on:

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

Question 15

Which of the following represents small molecules that fit into specific enzymes and aid in the catalytic process?

A) essential nutrients
B) macronutrients
C) micronutrients
D) cofactors
E) substrates

Question 16

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

A) It is found in the periplasm of Gram-negative cells.
B) It is found tethered 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 17

__________ form the base of the marine food chain.

A) Protists
B) Small fish
C) Sunlight
D) Cyanobacteria
E) Heterotrophs

Question 18

Which of the following is a micronutrient?

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

Question 19

A(n) __________ is an organism that lives in a close and mutually beneficial association with a second organism.

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

Question 20

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 21

What type of growth pattern is represented here: 5* 10³; 1 * 10⁴; 2 *0 10⁴; 4 * 10⁴; 8 *10⁴?

A) linear
B) exponential
C) lag
D) generation
E) semilogarithmic

Question 22

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

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

Question 23

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

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

Question 24

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 25

Siderophore-iron complexes enter cells with the help of:

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

Question 26

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

Question 27

All of the following are true about the MacConkey medium EXCEPT:

A) It is selective.
B) It is differential.
C) It is both selective and differential.
D) It contains bile salts.
E) Lactose fermenters appear colorless.

Question 28

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

A) The Enzyme II complex is 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.
D) The PTS transport requires energy in the form of ATP.
E) The system has a modular design that accommodates different substrates.

Question 29

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

A) Endospores
B) Parasites
C) Symbionts
D) Planktonic cells
E) Heterocyst cells

Question 30

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 31

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

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

Question 32

Growth of most microorganisms occurs by:

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

Question 33

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 34

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 35

Quorum sensing begins during which growth stage?

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

Question 36

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

Question 37

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

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

Question 38

__________ intercalates between DNA bases, causing dead cells to stain red under a fluorescence scope.

A) Propidium iodide
B) Syto-9
C) Ethidium bromide
D) Crystal violet
E) Safranin

Question 39

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 40

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 rate
E) log phase

Question 41

Which of the following genera does NOT undergo differentiation?

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

Question 42

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

Question 43

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

Question 44

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

Question 45

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

Question 46

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) siderophores iron acquisition
D) polysaccharides uptake
E) density sensing

Question 47

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

Question 48

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

Question 49

A cafeteria worker who fails to wash his hands thoroughly and fails to wear gloves inoculates a quiche with four 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 50

How do some cyanobacteria fix nitrogen while growing aerobically?

A) They don't, because nitrogenase is destroyed by oxygen.
B) They use special cells called heterocysts that protect the enzyme.
C) They use cysts 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 51

Mannitol salt agar (MSA) contains 7.5% NaCl, the carbohydrate mannitol, and the pH indicator phenol red. Some organisms can ferment mannitol, producing acids as a by-product. Is this medium likely to be selective and/or differential? Explain.

Question 52

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.

Question 53

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

Question 54

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 lower temperature
D) transfer to a different pH
E) transfer to a different salt concentration

Question 55

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

Question 56

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 57

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 58

Some bacteria form environmentally resistant forms called:

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

Question 59

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

Question 60

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 61

E. coli reprograms during the stationary phase. What are some of the things it does to protect itself?

Question 62

Discuss some disadvantages of viable counts of microorganisms.

Question 63

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

Question 64

What causes an organism to go through the process of sporulation? How can endospores cause problems in the food industry?

Question 65

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

Question 66

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 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

When using the LIVE/DEAD staining procedure, how can you distinguish live versus dead cells, and why do they appear in different colors?

Question 69

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

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.