1) Generally, membrane filters are not used to remove a) bacteria from liquids b
ID: 210284 • Letter: 1
Question
1) Generally, membrane filters are not used to remove
a) bacteria from liquids
b) microorganisms from gases
c) spoilage agents from alcoholic beverages
d) enzymes
2) plain soap is very effective in controlling spread of microorganisms because it is
a) bacteriostatic
b) very effective at the mechanical removal of microoorganisms
c) virucidal
d) bactericidal
3) the endospores of Pseudomas make that organism very difficult to kill. True or False
4) Pasterurization results in the sterilization of food products. True or False.
7) One would expect most strict anaerobic organisms to have superoxide dismutase. True or False.
8) Differential media only allows certain bacteria to grow. True or False.
9) Freezing is an effective means of destroying bacteria. True or False.
10) 100% ethanol is twice as effective as 60% ethanol at controlling bacteria. True or False.
Explanation / Answer
Question: 1
Generally membrane filters are not used to remove.
Answer: d) enzymes
Membrane filtration is the technique which is used to separate substances using thin layer of semi permeable membrane. It is used for the removal of bacteria, microorganisms, particulates, and natural organic materials.
Membrane filtration cannot block enzymes.
Question: 2
Plain soap is very effective in controlling spread of microorganisms because it is
Answer: b) very effective at the mechanical removal of microorganisms
Soap is the surface active agent which has antimicrobial activity. pH of the soap is usually alkaline which destroys some bacteria.
Question: 3
The endospores of Pseudomas make that organisms very difficult to kill
Answer: False
Bacterial endospores usually can with stand the environmental conditions such as high temperature, uv radiation, chemical damage and enzymatic distruction. But an autoclave can be used to kill bacterial endospores, because they cannot withstand temperature higher than 100
Question: 4
Pasteurization results in the sterilization of food products
Answer: False
Pasteurization is the technique which is used to slow down the growth of microbes in the food products such as milk by heating to specific temperature. Kills only vegetative cells.
Sterilization techniques are used to eliminate the microbes from any products not only liquid, solid surfaces, instruments etc. It uses high temperature to eliminate vegetative cells and also spores.
Question: 5
One would expect most anaerobic organisms to have superoxide dismutase
Answer: False
Oxygen can be easily reduced to superoxide and hydrogen peroxide in cells. Aerobic organisms produce superoxide dismutase enzyme to detoxify these agents. But this enzyme superoxide dismutase is not present in anaerobic organisms.
Question: 6
Differential media only allows certain bacteria to grow
Answer: False
Selective media only allows certain bacteria to grow and inhibit the growth of other.
Differential media allows the growth of groups of organisms. Differential media is used to differentiate organisms by presence of certain chemical or dye in the media.
Question: 7
Freezing is the effective means of destroying bacteria.
Answer: False
Freezing cannot kill bacteria, but it is inactive. It can revert back to active state when conditions are favourable.
Question: 8
100% ethanol is twice as effective as 60% ethanol at controlling bacteria
Answer: False
60% ethanol is effective than 100% ethanol because pure ethanol when poured on bacteria it coagulates the protein of the cellwall but cannot penetrate the organism. So it can be still active when the condition favours. When 60% ethanol is used the water enables the ethanol to pass through bacterial cell wall and it is effective in denaturing the proteins inside bacterial cell wall which kills them and thus it is effective.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.