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Microbiology Chapter 6 Questions and Answers
(100% Correct Answers)
What are the five groups of microbes based on preferred temperature?
Ans: Psychophiles
Psychotrophs
Mesophiles
Thermophiles
Hyperthermophiles
Why and How is the pH of culture media controlled?
Ans: Certain cultures will only grow within a certain pH range. You add acids or
bases to control the pH.
what is the importance of osmotic pressure to microbial growth?
Ans: A hypertonic enviroment, or an increase in salt or sugar cause plasmolysis.
Microbes need a certain osmotic pressure to maintain integrity and get nutrients.
Explain how microbial growth occurs
Ans: Microbes multiply by binary fission and increase in number of cells, not cell
size. Microbe-Populations-Colonies
What are the physical requirements for growth for microbes?
Ans: Temperature
pH
Osmotic Pressure
What are the chemical requirements for growth for microbes?
Ans: Carbon, Nitrogen, Sulphur, Phosphorus, Trace Elements, Oxygen, Organic
Growth Factor
What is the optimum temperature for Thermophiles
Ans: Optimum Temp is 65 degrees celcius
Range is 40 degrees celcius----->72 degrees celcius
What is the pH of bacteria?
Ans: Most bacteria grow between ph 6.5 and 7.5
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What is the pH of Molds and Yeasts?
Ans: 5 and 6
What is the pH of Acidophiles?
Ans: Very acidic environments
Which microbes cause food spoilage?
Ans: Psychotrophs. They grow between 0 degrees celcius and 30 degrees celcius.
Danger Zone food temperatures
Ans: between 41° and 135° fahrenheit
Which microbes require high Osmotic Pressure?
Ans: Obligate Halophiles and Extreme Halophiles
Which microbes tolerate (not require) high Osmotic Pressure?
Ans: Faculative Halophiles
What is plasmolysis?
Ans: When cell is in a hypertonic solution, Water leaves the cell and the plasma
membrane shrinks away from the cell wall.
Why are thermophiles that grow at temperatures above 100 degrees celcius
seemingly limited to oceanic depths?
Ans: The ocean depths are the only places you'll find these temperatures and
pressure needed for these microbes to live. The deep pressure at ocean depths
prevents water from boiling.
Other than controlling acidity, what is an advantage of using phosphate salts as
buffers in growth media?
Ans: Phosphorus buffers in the range of most bacteria, it provides necessary
nutrients and is non toxic.
Why might primitive civilizations have used food preservation techniques that rely
on osmotic pressure?
Ans: Bacteria need water to survive and grow. Salt used as a preservative will draw
water out of bacteria cells and cause them to die.
Carbon Phosphorus Nitrogen Sulfur
Ans: Most important biological elements
Carbon- Energy Source, Structural organic molecules
Phosphorus- In DNA, RNA, ATP and membranes
Nitrogen- In Amino Acids and Proteins, Most bacteria decompose nitrogen.
Microbiology Chapter 6 Questions and Answers
(100% Correct Answers)
What are the five groups of microbes based on preferred temperature?
Ans: Psychophiles
Psychotrophs
Mesophiles
Thermophiles
Hyperthermophiles
Why and How is the pH of culture media controlled?
Ans: Certain cultures will only grow within a certain pH range. You add acids or
bases to control the pH.
what is the importance of osmotic pressure to microbial growth?
Ans: A hypertonic enviroment, or an increase in salt or sugar cause plasmolysis.
Microbes need a certain osmotic pressure to maintain integrity and get nutrients.
Explain how microbial growth occurs
Ans: Microbes multiply by binary fission and increase in number of cells, not cell
size. Microbe-Populations-Colonies
What are the physical requirements for growth for microbes?
Ans: Temperature
pH
Osmotic Pressure
What are the chemical requirements for growth for microbes?
Ans: Carbon, Nitrogen, Sulphur, Phosphorus, Trace Elements, Oxygen, Organic
Growth Factor
What is the optimum temperature for Thermophiles
Ans: Optimum Temp is 65 degrees celcius
Range is 40 degrees celcius----->72 degrees celcius
What is the pH of bacteria?
Ans: Most bacteria grow between ph 6.5 and 7.5
, 2 Inquire through: | Professional | Confidential Support
What is the pH of Molds and Yeasts?
Ans: 5 and 6
What is the pH of Acidophiles?
Ans: Very acidic environments
Which microbes cause food spoilage?
Ans: Psychotrophs. They grow between 0 degrees celcius and 30 degrees celcius.
Danger Zone food temperatures
Ans: between 41° and 135° fahrenheit
Which microbes require high Osmotic Pressure?
Ans: Obligate Halophiles and Extreme Halophiles
Which microbes tolerate (not require) high Osmotic Pressure?
Ans: Faculative Halophiles
What is plasmolysis?
Ans: When cell is in a hypertonic solution, Water leaves the cell and the plasma
membrane shrinks away from the cell wall.
Why are thermophiles that grow at temperatures above 100 degrees celcius
seemingly limited to oceanic depths?
Ans: The ocean depths are the only places you'll find these temperatures and
pressure needed for these microbes to live. The deep pressure at ocean depths
prevents water from boiling.
Other than controlling acidity, what is an advantage of using phosphate salts as
buffers in growth media?
Ans: Phosphorus buffers in the range of most bacteria, it provides necessary
nutrients and is non toxic.
Why might primitive civilizations have used food preservation techniques that rely
on osmotic pressure?
Ans: Bacteria need water to survive and grow. Salt used as a preservative will draw
water out of bacteria cells and cause them to die.
Carbon Phosphorus Nitrogen Sulfur
Ans: Most important biological elements
Carbon- Energy Source, Structural organic molecules
Phosphorus- In DNA, RNA, ATP and membranes
Nitrogen- In Amino Acids and Proteins, Most bacteria decompose nitrogen.
