Methods In Microbial Ecology Ch29 Test Bank Docx

Prescott's Microbiology, 11e (Willey)

Chapter 29 Methods in Microbial Ecology

1) What percentage of microbes have been cultured in the laboratory?

A) 1%

B) 10%

C) 20%

D) 30%

2) A traditional technique used to quantify specific types of microbes in natural samples, enrichment cultures, and food or water samples is known as the ________ ________ ________ technique.

3) ________ cultures are pure cultures, consisting of a single species.

4) The use of modern molecular techniques has provided a mechanism for growing some of the microorganisms previously referred to as unculturable.

5) The discrepancy between the number of microbial cells observed by microscopic examination and the number of colonies that can be cultivated from the same natural sample may be due to ________.

A) nonviable organisms

B) incorrect culture conditions

C) microbial motility

D) nonviable organisms and incorrect culture conditions

6) ________ culture techniques are based on the expansion of the microenvironment to allow abundant growth of a microorganism formerly restricted to a small ecological niche.

7) Optical tweezers can be used to ________.

A) help dissect individual microorganisms

B) remove structures from the surface of cells

C) study nucleic acids recovered from individual cells

D) All of the choices are correct.

8) Recent evidence suggests that most microbial communities have many individuals representing at least ________ taxa.

A) 1,000

B) 100,000

C) 10,000,000

D) 1,000,000,000

9) Determining the functional nature of a microbial community by analysis of bulk DNA samples extracted from environmental samples may be misleading for all of the following reasons EXCEPT ________.

A) DNA is of little use in identifying unknown microbes

B) some of the DNA recovered may be from nonliving organisms

C) some of the DNA may be from entities such as spores

D) the DNA obtained can depend on the extraction method used

10) When PCR amplification of SSU (small subunit ribosomal RNA) yields a population of different PCR products of about the same molecular weight, these fragments can be separated for further analysis by ________.

A) isoelectric focusing

B) size exclusion chromatography

C) denaturing gradient gel electrophoresis

D) DNA hybridization

11) When doing SSU (small subunit ribosomal RNA) of a mixed population of microbes from an environmental sample, specific ________ are identified.

A) phenotypes

B) phylotypes

C) genotypes

D) unknown microbes

12) It is generally agreed that SSU (small subunit ribosomal RNA) analysis is a technique that is well suited to identifying species present in a given community.

13) Which of the following is microscopy in which the microscope is fitted with light filters that enable the excitation of the specimen with a specific wavelength?

A) Epifluorescence microscopy

B) Electron microscopy

C) Bright-field microscopy

D) Dark-field microscopy

14) When fluorescently labeled oligonucleotides that are known to be specific to the microbe of interest are used to label natural samples, the technique is known as ________.

A) polymerase chain reaction

B) fluorescent in situ hybridization

C) epifluorescence microscopy

D) gel electrophoresis

15) The fact that certain nucleotide templates are more readily amplified than others is termed ________.

A) multiplex PCR

B) analytical PCR

C) real-time PCR

D) PCR bias

16) The level of specific mRNA, and therefore the expression of a given gene in a particular ecosystem, can be evaluated in the environment using in situ reverse transcriptase (ISRT)-FISH.

17) The goal of ________ is to identify each protein present in a given microenvironment at the time of sampling.

A) metagenomics

B) metaproteomics

C) both metagenomics and metaproteomics

D) None of the choices are correct.

18) Stable isotope analysis to indicate whether or not certain elements have been processed by an organism is based on the observation that ________.

A) microbes have no preference with regard to heavy versus light isotopes

B) microbes generally prefer using the heavier of two stable isotopes

C) microbes generally prefer using the lighter of two stable isotopes

D) None of the choices are correct.

19) In two-dimensional nano-liquid chromatography, a complex mixture of peptides is separated first by charge and then by solubility.

20) ________ techniques are based on recreating a microenvironment in the laboratory to promote the growth of a microorganism formerly restricted to a small ecological niche.

A) Enrichment culture

B) Fastidious growth

C) PCR

D) Community growth

21) In ________ ________, cells are tagged with a fluorescent dye and injected into a flowing, progressively narrowing stream of fluid, forcing one cell at a time through a laser beam that scatters its fluorescence to a detector.

22) While there are many uses for flow cytometry, a powerful addition to this technique is the ability to further sort, count, and collect individual fluorescent cells, known as fluorescence activated cell sorting (FACS).  

23) Because so few bacteria can be grown easily in culture but all of them contain DNA, molecular techniques like PCR and SSU rRNA are used to be able to identify and quantify microorganisms as a "census" for diversity.

24) The technique known as ________ relies on the fact that although the PCR fragments are about the same ________, they differ in ________.  The DNA denaturing rate on a gel then varies with the ________ content, DNA sequence, and chemical gradient. Hence, similar fragments can be separated and identified.

25) In a ________ assay, DNA extracted from a microbial community or environmental sample is incubated with selected complementary probe or sample sequences (often ________) and allowed to hybridize. The level of hybridization to each probe (gene) is measured. Analysis of DNA hybridization thus reveals the presence or absence of the specific genes in the environment.  Most importantly, this can be done without ________. 

26) Suppose a microbiologist wanted to assess the microbial community in a gram of forest soil. Which of the following technique(s) would help them to enumerate a specific genus or type of microbe? (Check all that apply.)

A) Fluorescent in-situ hybridization (FISH)

B) Catalyzed reported deposition-FISH (CARD-FISH)

C) Optical tweezers

D) Phylochip

27) Suppose a marine microbiologist wanted to assess the microbial community in a milliliter of sea water. Which of the following technique(s) may be useful to help them enumerate a specific genus or type of microbe? (Check all that apply.)

A) DAPI nucleic acid stain

B) Fluorescence activated cell sorting (FACS)

C) Catalyzed reported deposition-FISH (CARD-FISH)

D) Most probable number (MPN) technique

28) Microbial ecologists seek to understand how microbes drive and respond to the biogeochemical cycles that are essential for life on Earth. However, at this time it is only possible to make concrete connections, identifications, or measurements about the abiotic flux of nutrients rather than the interactions between microbes that make these fluxes possible.

29) In the study of microbial communities, a new technique using microelectrodes is helping us to infer data about microbial activity. Microelectrodes are capable of measuring which of the following data? (Check all that apply.)

A) Measuring pH

B) Measuring DNA amounts in the sample

C) Measuring electron donors and receptors

D) Measuring oxygen and nitrogen tension

30) Which of the following samples of microbial communities would be best suited for study by microelectrode experiments?

A) Striated microbial mats

B) Ten gallons of seawater

C) Sample sorted by optical tweezers

D) During infection in a human patient

31) The technique known as ________ ________ ________ can be used to examine nutrient cycling in microbial communities as well as identify the microbes taking up the element of interest. 

32) In situ mRNA techniques are powerful and can be run at almost any time, in any condition, because bacterial mRNAs are so stable.

33) Suppose a microbiologist wanted to identify the microbe responsible for a specific metabolic activity. To simultaneously assess metabolic activity and phylogenetic identity, the best technique would be ________.

A) microautoradiography with fluorescent in situ hybridization (MAR-FISH)

B) metatranscriptomics

C) isotope fractionation

D) optical tweezers with microelectodes

34) When MAR is combined with FISH, one can analyze the phylogenetic identity and the specific substrate uptake patterns of microbes of interest at the level of a single cell in complex microbial communities.

35) The most probable number (MPN) technique is an approach that can be used to quantify the presence of a particular microbe whether or not that microbe is culturable.

36) Bacteria that normally require communication signals from other microbes in their environment in order to grow may seem to be unculturable in the laboratory. What are some strategies that could be used to promote culturing of these bacteria? (Check all that apply.)

A) Grow in spent medium of the other organism

B) Increase the incubation time of the culture

C) Use vPCR to differentiate between live and dead cells

D) Co-cultivate with the other organism

37) It is beneficial to study microbial communities in situ because ________.

A) microbes can be studied even if they are nonculturable

B) in situ studies maintain the relative concentrations of different microorganisms in a sample

C) gene expression may be different in an environmental sample versus an anexic culture

D) All of these are reasons to study microbial communities in situ.

38) Phylochips assess the relative abundance of a microbe in a community by reporting the fluorescence intensity of its specific ________.

A) 16S rRNA

B) radioactive isotopes

C) ribosomal proteins

D) lipids

39) Understanding the abiotic microenvironment of a community is not very informative when studying the microbial populations in that environment.