Deck 6: Microbial Nutrition and Growth

Question 1

During which growth phase are bacteria more susceptible to antimicrobial drugs?

A) death phase
B) stationary phase
C) lag phase
D) log phase
E) The susceptibility is the same for all phases.

Answer 1

D

Question 2

A device that removes wastes and adds fresh medium to bacterial cultures in order to prolong the log phase of a culture is called a

A) spectrophotometer.
B) cytometer.
C) chemostat.
D) Coulter counter.
E) pellicle.

Answer 2

C

Question 3

A cell that uses an organic carbon source and obtains energy from light would be called a

A) lithoautotroph.
B) chemoautotroph.
C) photoheterotroph.
D) chemoheterotroph.
E) photoautotroph.

Answer 3

C

Question 4

A Petroff- Hauser counting chamber is a(n)

A) device that counts cells as they interrupt an electrical current.
B) glass slide containing an etched grid for counting microbes directly using a microscope.
C) apparatus that traps bacterial cells on a membrane filter where they can be counted.
D) device that measures the amount of light that passes through a culture.
E) device used to count numbers of bacterial colonies on a Petri plate.

Question 5

An aquatic microbe that can grow only near the surface of the water is probably which of the following?

A) a lithotroph
B) an anaerobe
C) a chemotroph
D) a heterotroph
E) a phototroph

Question 6

An organism that produces catalase enzyme is protected from the harmful effects of

A) peroxide anion.
B) hydroxyl radical.
C) molecular oxygen.
D) superoxide radical.
E) singlet oxygen.

Question 7

The correct sequence for the phases indicated by the letters A, B, C and D is

A) stationary phase, lag phase, log phase, death phase.
B) death phase, log phase stationary phase, lag phase.
C) death phase, stationary phase, log phase, lag phase.
D) lag phase, log phase, stationary phase, death phase.
E) log phase, stationary phase, lag phase, death phase.

Question 8

Joan wants to discover a microbe capable of degrading an environmental contaminant. Which of the following is the process she should use?

A) nitrogen fixation
B) chemostat
C) enrichment culture
D) quorum sensing
E) cell culture

Question 9

An epidemiologist is investigating a new disease and observes what appear to be bacteria inside tissue cells in clinical samples from victims. The scientist wants to try to isolate the bacteria in the lab. What culture conditions are most likely to be successful?

A) incubation in an anaerobic culture system
B) inoculation of cell cultures
C) culturing on blood agar plates
D) inoculation of a minimal medium broth
E) inoculation of EMB plates

Question 10

A laboratory protocol lists the following ingredients: 1 g sucrose, 16.4 g Na2HPO4, 1.5 g (NH4)3PO4, 0.02 g CaCO3, KNO3, water to 1 liter and autoclave. This recipe is for a medium.

A) complex broth
B) defined agar
C) complex enrichment broth
D) defined broth
E) reducing agar

Question 11

Blood agar plates are an example of medium.

A) selective
B) transport
C) differential
D) reducing
E) defined

Question 12

A means of reproduction in which duplicate DNA molecules are separated by cell elongation, followed by formation of a septum to divide the cytoplasm is called

A) mitosis.
B) cell division.
C) budding.
D) logarithmic growth.
E) binary fission.

Question 13

Sodium thioglycollate is associated with which of the following types of media?

A) transport media
B) differential media
C) selective media
D) complex media
E) reducing media

Question 14

The of a population is the time it takes for the cells to double in number.

A) generation time
B) log phase
C) binary fission
D) arithmetic growth
E) exponential growth

Question 15

Obligate anaerobes may be cultured in the laboratory

A) on blood agar plates.
B) in a reducing medium.
C) standard complex media.
D) in a standard incubator.
E) in standard Petri plates.

Question 16

Microbial growth rates are controlled in a chemostat by

A) controlling the amount of a limiting nutrient.
B) allowing waste products to accumulate.
C) promoting biofilm formation.
D) controlling the amount of available oxygen.
E) maintaining a constant temperature.

Question 17

At temperatures higher than the maximum growth temperature for an organism,

A) membranes become too fluid for proper function.
B) proteins are permanently denatured.
C) hydrogen bonds within molecules are broken.
D) hydrogen bonds are broken and proteins are permanently denatured.
E) hydrogen bonds are broken, proteins are denatured, and membranes become too fluid.

Question 18

A microbiologist inoculates a growth medium with 100 bacterial cells/ml. If the generation time of the species is 1 hour, and there is no lag phase, how long will it be before the culture contains more than 10,000 cells/ml?

A) 24 hours
B) 10 hours
C) 7 hours
D) 3 hours
E) 2 hours

Question 19

An organism that requires chemical nutrients which serve as final electron acceptors is a(n)

A) phototroph.
B) lithotroph.
C) autotroph.
D) chemotroph.
E) aerobe

Question 20

In the process of microbes detect the presence and density of other microbes and modify their metabolic activity in response.

A) quorum sensing
B) synergy
C) mutualism
D) symbiosis
E) antagonism

Question 21

A capnophile is a microorganism that thrives in conditions of high

A) pH.
B) hydrostatic pressure.
C) oxygen levels.
D) salt concentration.
E) carbon dioxide levels.

Question 22

Human pathogens are classified as

A) mesophiles.
B) hyperthermophiles.
C) psychrophiles.
D) thermoduric.
E) thermophiles.

Question 23

The method provides an estimate of the CFUs (colony- forming units) in a sample

A) direct microscopic- count
B) Coulter- counter
C) streak- plate
D) turbidity
E) viable plate- count

Question 24

Which of the following organisms would be most likely to contaminate a jar of pickles?

A) a mesophile
B) an acidophile
C) a neutrophile
D) a thermophile
E) an obligate anaerobe

Question 25

The generation time of bacterial cells is shortest during the phase.

A) stationary
B) log
C) longitudinal
D) lag
E) death

Question 26

Which of the following quantification techniques can distinguish living cells from dead cells in a culture?

A) a Coulter counter
B) metabolic activity
C) microscopic counts
D) dry weight
E) turbidity

Question 27

Creating conditions in the laboratory that promote the growth of some microbes while inhibiting the growth of others is called

A) transport conditions.
B) complex culturing.
C) reducing conditions.
D) differential culturing.
E) selective enrichment culturing.

Question 28

When cells are metabolically active but not dividing, they are in the phase.

A) death
B) stationary
C) log
D) exponential
E) lag

Question 29

A 100 µl sample containing 1000 bacterial cells/µl in log phase growth is added to 9.9 ml of fresh culture medium broth. Assuming no nutrients are in limited supply, and a generation time of 30 minutes, how many bacteria will be present in the entire broth culture after six hours?

A) 6.0 × 10⁶
B) 1.2 × 10⁶
C) 4.096 × 10⁸
D) 6.0 × 10⁵
E) 2.56 × 10⁷

Question 30

Metabolic activity is at maximum level in the _ phase of growth.

A) stationary
B) lag
C) death
D) log
E) intermediate

Question 31

The method of obtaining isolated cultures that utilizes surface area to physically dilute specimens is called

A) the pour- plate technique.
B) serial dilution.
C) enrichment culturing.
D) the streak- plate technique.
E) transport media.

Question 32

Which of the following is an indirect method for estimating the number of microbes in a sample?

A) membrane filtration
B) Coulter counter
C) turbidity
D) MPN
E) viable plate counts

Question 33

Microaerophiles are microbes that grow best at low

A) pH values.
B) salt concentrations.
C) hydrostatic pressure.
D) oxygen levels.
E) carbon dioxide levels.

Question 34

A microbe recovered from an environmental sample grows on a medium composed of agar and a mix of salts. The agar is not digested during incubation. The growth rate increases in high CO2 conditions. The organism is likely a(n)

A) chemotroph.
B) autotroph.
C) halophile.
D) heterotroph.
E) The answer cannot be determined from the information provided.

Question 35

Nitrogen is a growth- limiting nutrient for many organisms because

A) it is required for lipid synthesis.
B) it is required for synthesis of nucleotides.
C) only a small number of bacteria are able to extract it from the atmosphere.
D) it is necessary for the biosynthesis of amino acids.
E) only a few microbes can extract it from the atmosphere, but all organisms require it for amino acid and nucleotide synthesis.

Question 36

The use of salt and sugar in preserving various types of foods is an application of which of the following concepts?

A) hydrostatic pressure
B) quorum sensing
C) osmotic pressure
D) nitrogen fixation
E) pH

Question 37

are complex communities of various types of microbes that adhere to surfaces.

A) Aggregates
B) Media
C) Biofilms
D) Colonies
E) Isolates

Question 38

Organisms that can grow with or without oxygen present are

A) either facultative anaerobes or aerotolerant anaerobes.
B) aerotolerant anaerobes.
C) obligate anaerobes.
D) obligate aerobes.
E) facultative anaerobes.

Question 39

A fastidious organism might be grown on which of the following types of media?

A) enriched media
B) reducing media
C) selective media
D) differential media
E) transport media

Question 40

MacConkey agar plates represent _ _ medium.

A) a minimal
B) a differential
C) a selective
D) both a differential and a selective
E) both a minimal and a selective

Question 41

A microorganism found living under conditions of high is a barophile.

A) carbon dioxide levels
B) hydrostatic pressure
C) salt concentrations
D) pH values
E) oxygen concentrations

Question 42

Alkalinophiles can survive in water up to pH (11.5/10/7.0).

Question 43

Many photosynthetic organisms produce (catalase/carotenoids/dismutase) to protect themselves from the damaging effects of singlet oxygen (1O2).

Question 44

A clinical sample of (urine/sputum/tissue) is called a biopsy.

Question 45

The (peroxide/superoxide/hydroxyl) radical is formed during the incomplete reduction of O2 during electron transport in aerobes.

Question 46

A sample placed into fresh medium is initially in the (lag/log/stationary) phase of microbial growth in most instances.

Question 47

A(n) (culture/specimen/inoculum) is a sample of microorganisms introduced into a growth medium.

Question 48

Organisms that require organic sources of carbon and energy are called (chemoheterotrophs/chemoautotrophs/auxotrophs).

Question 49

A(n) organism require(s) oxygen for growth.

A) aerotolerant and an anaerobic
B) aerotolerant
C) obligate aerobic
D) anaerobic
E) facultative anaerobic

Question 50

A gelling agent derived from algae that is useful for creating solid growth media is called (broth/agar/starch).

Question 51

The (optimum/range/minimum) growth temperature is the temperature at which an organism exhibits the highest growth rate.

Question 52

A pure culture is composed of cells that arise from a single (cell/inoculum/sample).

Question 53

All of the following are used to protect organisms from the toxic by- products of oxygen EXCEPT

A) carotenoids.
B) catalase.
C) peroxidase.
D) protease.
E) superoxide dismutase.

Question 54

Flow (spectrophotometry/cytometry) is a method of counting cells that have been stained or tagged with fluorescent dyes.

Question 55

A (cytometer/spectrophotometer) can measure changes in the turbidity of a bacterial culture.

Question 56

A growth curve plots the (number/concentration) of viable organisms in a growing population over time.

Question 57

The preferred method for long term storage of bacteria is (freezing/refrigeration/lyophilization).

Question 58

The conversion of nitrogen gas to ammonia is called nitrogen (metabolism/fixation).

Question 59

A clinical sample labeled as "sputum" was collected from

A) the lungs.
B) the blood.
C) the central nervous system.
D) the skin.
E) a piece of tissue.

Question 60

A microbe that grows only at the bottom of a tube of thioglycollate medium is probably a(n)

A) facultative anaerobe.
B) obligate anaerobe.
C) obligate aerobe.
D) microaerophile.
E) aerotolerant anaerobe.

Question 61

Obligate anaerobes have enzymes such as superoxide dismutase to protect them from the damaging effects of oxygen.

Question 62

Agar is a useful compound in the microbiology lab because it is an excellent nutrient for bacteria.

Question 63

The only effective way to store bacterial cultures for short periods of time is to arrest their metabolism by freezing.

Question 64

Explain how temperature and pH levels can influence microbial infections in the human body.

Question 65

A new prokaryote is recovered from a remote saline hot spring. Design a set of experiments to determine whether the organism is thermophilic or thermoduric, halophilic or halotolerant.

Question 66

Nitrogen fixation is a process that occurs in all bacteria.

Question 67

Explain the similarities and differences between direct and indirect methods of measuring microbial growth, and give examples of each.

Question 68

In spectrophotometry, 40% light transmission is the same thing as 60% absorbance of light.

Question 69

Quorum sensing is involved in the development and propagation of a biofilm.

Question 70

Genetic methods of detecting microorganisms reveal that the number of bacterial species in nature exceeds previous estimates by several orders of magnitude. In the human mouth, for example, it is estimated that 500- 700 microbial species are normally present. Explain why previous estimates were low.

Question 71

A selective medium can be formulated either by including inhibitory chemical substances or by leaving out a single crucial nutrient.

Question 72

Compare and contrast the streak- plate method of isolation with the pour- plate method of isolation.

Question 73

An obligate anaerobe can be cultured in a candle jar.

Question 74

Thermoduric mesophiles are often responsible for spoilage of improperly canned foods.

Question 75

Serial dilution can be used in combination with pour plates as a method for isolating pure cultures.