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Exam 2 CH 5 & 6
Terms in this set (48)
Bacteriochlorophyll a absorbs ________ light.
B) 350 nm, ultraviolet
Which of the following is an active enzyme?
A(n) ________ organism require(s) oxygen for growth
C) obligate aerobic
The growth of bacterial cultures is best described as
E) logarithmic growth.
Reducing medium is used to isolate ________ microbes.
B) obligate anaerobic
A 0.1 ml sample of a log phase culture contains 10,000 bacterial cells/ml. It is added to 9.9 ml of fresh culture medium broth. Assume a generation time of 30 minutes, and no limiting nutrients. How many bacteria will be present in the entire broth culture after five hours?
A) 1.02 × 106
________ are complex communities of various types of microbes that adhere to surfaces.
Blood agar plates are an example of ________ medium.
A clinical sample labeled as "sputum" was collected from
D) the lungs.
During which growth phase are bacteria more susceptible to antimicrobial drugs?
B) log phase
The carotenoid pigments of some phototrophs interact with ________ to reduce its toxicity.
B) singlet oxygen (1O2)
Which of the following methods provides information about the number of living cells in a sample of bacterial culture?
A) serial dilution and viable plate count
Which of the following is an indirect method for estimating the number of microbes in a sample?
The Most Probable Number (MPN) method is used
D) to estimate numbers of cells in samples with a low density of bacterial cells.
Nitrogen is a growth-limiting nutrient for many organisms because
C) only a few microbes can extract it from the atmosphere, but all organisms require it for amino acid and nucleotide synthesis.
Organisms that can grow with or without oxygen present are
E) either facultative anaerobes or aerotolerant anaerobes.
Creating conditions in the laboratory that promote the growth of some microbes while inhibiting the growth of others is called
B) enrichment culturing.
When cells are metabolically active but not dividing, they are in the ________ phase.
62) The ________ of a population is the time it takes for the cells to double in number.
A) generation time
63) A cell that uses an organic carbon source and obtains energy from light would be called a
64) A microbe that grows only at the bottom of a tube of thioglycollate medium is probably a(n)
B) obligate anaerobe.
65) A fastidious organism might be grown on which of the following types of media?
C) enriched media
66) At temperatures higher than the maximum growth temperature for an organism
A) hydrogen bonds are broken, proteins are denatured, and membranes become too fluid.
67) A ________ is used in industrial microbiology to produce microbial products that are only synthesized during log phase growth
68) The ________ method provides an estimate of the CFUs (colony-forming units) in a sample.
B) viable plate-count
69) During the synthesis of acetyl-CoA from pyruvic acid, ________ is produced.
70) An organism that requires chemical nutrients which serve as final electron acceptors is a(n)
71) Ted heats some food just to boiling, and stores some of it immediately in a container which he places in the refrigerator. A week later he takes the food out and finds it has spoiled. The microbes responsible are probably
72) The events of binary fission are
I. the cell doubles in size
II. the DNA is replicated
III. the cell forms a septum
IV. the cell separates from its offspring
D) II, I, III, IV.
73) A microbiologist inoculates a flask of broth to a concentration of 100 bacterial cells per ml. 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 6,000 cells per ml?
E) 6 hours
74) Microaerophiles are microbes that grow best at low
E) oxygen levels.
75) Obligate anaerobes may be cultured in the laboratory
B) in a reducing medium.
76) A microorganism grows in the lab on medium containing mineral salts but no organic compounds. The organism is likely to be a(n)
77) Pure cultures are often obtained by isolating
D) CFUs (colony forming units).
78) A microorganism found living under conditions of high ________ is a barophile.
E) hydrostatic pressure
79) A laboratory recipe lists sucrose, an ammonia compound, calcium salts and a buffer as the ingredients for a microbiologic medium. These are added to water and autoclaved. What type of medium does this protocol produce?
B) defined broth
The generation time of bacterial cells is shortest during the ________ phase.
The absence of ________ leaves obligate anaerobes susceptible to killing by oxygen.
D) superoxide dismutase
Joan wants to discover a microbe capable of degrading an environmental contaminant. Which of the following culturing methods would be most effective for isolation of such an organism?
B) enrichment culture
Which of the following organisms would be most likely to contaminate a jar of pickles?
E) an acidophile
In the process of ________, microbes detect the presence and density of other microbes and modify their metabolic activity in response.
D) quorum sensing
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?
C) inoculation of cell cultures
An aquatic microbe that can grow only near the surface of the water is probably which of the following?
A) a phototroph
The use of salt and sugar in preserving various types of foods is an application of which of the following concepts?
C) osmotic pressure
MacConkey agar plates represent ________ medium.
D) both a differential and a selective
Which of the following statements is CORRECT regarding Figure 6.1?
D) No new cells are being produced during the stage represented by C.
A capnophile is a microorganism that thrives in conditions of high
D) carbon dioxide levels.
Rates of cell production and cell death are approximately equal during the ________ phase of growth.
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