Micro Lab Final Exam with Correct Answers
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Terms in this set (147)
Chapter 7: Environmental
Conditions
Which organism showed the Bacillus megaterium because bacillus species produce
best survival at each time and endospores that survive until conditions are optimal to germinate
temperature? Give an into vegetative cells
explanation for this.
- Sterilization is the killing of living organisms and viruses from a
Define sterilization. How does
growth medium.
this differ from pasteurization?
- Pasteurization eliminates organisms that cause food spoilage.
Why does spoilage still occur in
- Cause the species Bacillus can survive and grow in cold
milk that has been pasteurized?
temperatures
What is meant by temperature - bacteria grows at a wide range of temp even in boiling water
range for growth? What is meant (41-135)
by optimal temperature? - bacteria grows most rapidly at a certain amount of temperature
An organism which can grow Mesophiles
well at body temperature is
termed a
What is the physiological reason The rate of cellular enzyme activity diminishes and lipids in the
that organisms grow best at their cell membranes begin to solidify, impairing membrane function
optimal temperature?
Why does excessively high heat As temp exceed the optimum, critical enzymes become
kill most organisms? denatured and thermal destruction of cellular structures
Explain briefly how the addition - Acids lower the pH of food, extreme deviation results in
of acid can be used to preserve denaturation of proteins
foods, and give three examples - fruit, soda, pickles
of foods to which acids are
added as a preservative.
Which organism was better able - Bacillus Megaterium because it produces endospores
to survive exposure to UV - Deinococcus radiourans because it repairs DNA damage
radiation? Why? induced by UV radiation, very efficient process
Which organism survived both - Both Bacillus megaterium
UV radiation exposure and high - only Deinococcus radiodurans
temperature? Which organism - b.m prouduce endospores while d.r repairs thymine dimers
survived UV radiation exposure, mechanism induced by UV radiation
but not high temperature?
Explain the difference in survival
between these two organisms.
Name two different reasons Either produces endospores or have mechanisms to fix mutation
microorganisms may be able to cause by UV radiation
survive UV.
, What part of the bacterial cell - DNA strands
does the UV radiation damage? - lethal mutations
What is the specific type of - it can distort the structure of DNA and prevent replication and
damage? How does this transcription from occurring
influence cell survival?
Which organism(s) showed the - staphylococcus epidermis
greatest range of osmotic - vibrio natriegens
tolerance?
Which organism could be - Halobacterium Salinarium (halophiles= growth in high salt
classified as an extreme solution)
halophile? A halotolerant - Staphylococcus epidermis (halotolerant= growth in low salt
organism? solution)
Explain how foods can be - Adding salt or sugar creates a hypertonic (water flows out of
preserved using salt or sugar. the cell when the concentration of the solute is greater outside
(Be sure to mention specifically the cell than inside it). The osmotic pressure dehydrates it causes
how the salt or sugar inhibits metabolic activities to stop and when that stops the cell growth
bacterial growth.) Give two rate decreases
examples of foods preserved - salt on fish, sugar/salt on ham
this way.
Why is Staphylococcus aureus It is a halotolerant microbe and ham naturally has a high salt
food "poisoning" often content so it is able to survive within ham
associated with foods such as
ham?
Chapter 8: Inhibition of Microbial
Growth
Explain the difference between Disinfectant applies to inanimate surfaces ( table tops) while
disinfectants and antiseptics. antiseptics can be applied to surface (skin)
Give an example of where each
might be properly used.
What is the difference between - static agent inhibit growth of microorganisms
a static agent and a cidal agent? - cidal agent are lethal to microorganisms
Give examples of each.
What are some of the factors Concentration of disinfectant
that influence the activity of a contact time
disinfectant? dormant forms (endospores/biofilms)
Consider your results for It is resistance to a lot of antibiotics and can easily be spread by
Experiment 8. Why are human hands of workers or equipment which makes it hard to treat
pathogens such as
Pseudomonas aeruginosa of
concern in hospitals and other
places that care for the sick?
Both Bacillus megaterium and Bacillus has endospores which they can survive and grow in
Staphylococcus epidermidis are vegetative state
exposed to the same
disinfectant for the same amount
of time and it is noted that the
Bacillus was more resistant to
the action of the agent. How
could this be explained?
Save
Terms in this set (147)
Chapter 7: Environmental
Conditions
Which organism showed the Bacillus megaterium because bacillus species produce
best survival at each time and endospores that survive until conditions are optimal to germinate
temperature? Give an into vegetative cells
explanation for this.
- Sterilization is the killing of living organisms and viruses from a
Define sterilization. How does
growth medium.
this differ from pasteurization?
- Pasteurization eliminates organisms that cause food spoilage.
Why does spoilage still occur in
- Cause the species Bacillus can survive and grow in cold
milk that has been pasteurized?
temperatures
What is meant by temperature - bacteria grows at a wide range of temp even in boiling water
range for growth? What is meant (41-135)
by optimal temperature? - bacteria grows most rapidly at a certain amount of temperature
An organism which can grow Mesophiles
well at body temperature is
termed a
What is the physiological reason The rate of cellular enzyme activity diminishes and lipids in the
that organisms grow best at their cell membranes begin to solidify, impairing membrane function
optimal temperature?
Why does excessively high heat As temp exceed the optimum, critical enzymes become
kill most organisms? denatured and thermal destruction of cellular structures
Explain briefly how the addition - Acids lower the pH of food, extreme deviation results in
of acid can be used to preserve denaturation of proteins
foods, and give three examples - fruit, soda, pickles
of foods to which acids are
added as a preservative.
Which organism was better able - Bacillus Megaterium because it produces endospores
to survive exposure to UV - Deinococcus radiourans because it repairs DNA damage
radiation? Why? induced by UV radiation, very efficient process
Which organism survived both - Both Bacillus megaterium
UV radiation exposure and high - only Deinococcus radiodurans
temperature? Which organism - b.m prouduce endospores while d.r repairs thymine dimers
survived UV radiation exposure, mechanism induced by UV radiation
but not high temperature?
Explain the difference in survival
between these two organisms.
Name two different reasons Either produces endospores or have mechanisms to fix mutation
microorganisms may be able to cause by UV radiation
survive UV.
, What part of the bacterial cell - DNA strands
does the UV radiation damage? - lethal mutations
What is the specific type of - it can distort the structure of DNA and prevent replication and
damage? How does this transcription from occurring
influence cell survival?
Which organism(s) showed the - staphylococcus epidermis
greatest range of osmotic - vibrio natriegens
tolerance?
Which organism could be - Halobacterium Salinarium (halophiles= growth in high salt
classified as an extreme solution)
halophile? A halotolerant - Staphylococcus epidermis (halotolerant= growth in low salt
organism? solution)
Explain how foods can be - Adding salt or sugar creates a hypertonic (water flows out of
preserved using salt or sugar. the cell when the concentration of the solute is greater outside
(Be sure to mention specifically the cell than inside it). The osmotic pressure dehydrates it causes
how the salt or sugar inhibits metabolic activities to stop and when that stops the cell growth
bacterial growth.) Give two rate decreases
examples of foods preserved - salt on fish, sugar/salt on ham
this way.
Why is Staphylococcus aureus It is a halotolerant microbe and ham naturally has a high salt
food "poisoning" often content so it is able to survive within ham
associated with foods such as
ham?
Chapter 8: Inhibition of Microbial
Growth
Explain the difference between Disinfectant applies to inanimate surfaces ( table tops) while
disinfectants and antiseptics. antiseptics can be applied to surface (skin)
Give an example of where each
might be properly used.
What is the difference between - static agent inhibit growth of microorganisms
a static agent and a cidal agent? - cidal agent are lethal to microorganisms
Give examples of each.
What are some of the factors Concentration of disinfectant
that influence the activity of a contact time
disinfectant? dormant forms (endospores/biofilms)
Consider your results for It is resistance to a lot of antibiotics and can easily be spread by
Experiment 8. Why are human hands of workers or equipment which makes it hard to treat
pathogens such as
Pseudomonas aeruginosa of
concern in hospitals and other
places that care for the sick?
Both Bacillus megaterium and Bacillus has endospores which they can survive and grow in
Staphylococcus epidermidis are vegetative state
exposed to the same
disinfectant for the same amount
of time and it is noted that the
Bacillus was more resistant to
the action of the agent. How
could this be explained?
