GCSU BACHOON MICROBIOLOGY TEST 2
EXAM QUESTIONS WITH VERIFIED
SOLUTIONS NEW MODIFIED
what is a psychrotroph? --CORRECT ANSWER--- organism that is capable of
growth between 0 deg. C and 30 deg. C
mesophiles --CORRECT ANSWER--- moderate temperature loving microbes,
most common type
- (25 deg. C - 40 deg. C)
- these are human pathogens also include most of the common spoilage and
disease organisms.
- ex: 37 deg. C (the optimum temp. for many pathogenic bacteria)
thermophiles --CORRECT ANSWER--- heat loving microbes
- (40 deg. C - 70 deg. C)
- many can't grow at temps below 45 deg. C
- hyperthermophiles = (70 deg. C - 110 deg. C)
what temperature do pathogens grow at? --CORRECT ANSWER--- human
body temp. (37 degrees celsius)
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,what pH range do most bacteria grow best in? --CORRECT ANSWER--- a
narrow pH range
- neutral (6.5 - 7.5)
- very few grow below pH 4
- foods with low pH (cheese, pickles..) don't spoil easily)
What are some examples of bacteria that grow below pH 4? --CORRECT
ANSWER--- sulfur oxidizers
- H. pylori
____ have more H+ than ______ --CORRECT ANSWER--acids, bases
what is the osmotic pressure inside bacterial cells in an isotonic solution? --
CORRECT ANSWER--- 0.85% NaCl
What type of solution inhibits bacterial growth? --CORRECT ANSWER---
hypertonic solutions (solutes are higher outside the cell)
- water leaves the cell
Why do we study microbial growth? --CORRECT ANSWER--1) to prove what
causes disease
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, 2) for antibiotic susceptibility (how to kill)
3) for research
what are the physical aspects of microbial growth? --CORRECT ANSWER---
temperature
- pH
- osmotic pressure
what are the 3 main groups microbes are classified into based on their optimum
temperature? --CORRECT ANSWER--1) psychrophiles
2) mesophiles
3) thermophiles
psychrophiles --CORRECT ANSWER--- cold loving microbes
- don't cause disease
- (-10 deg. C to 20 deg. C)
what is plasmolysis? --CORRECT ANSWER--- the osmotic loss of water from
the cell in a hypertonic environment
- shrinkage of the cell plasma membrane - die
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EXAM QUESTIONS WITH VERIFIED
SOLUTIONS NEW MODIFIED
what is a psychrotroph? --CORRECT ANSWER--- organism that is capable of
growth between 0 deg. C and 30 deg. C
mesophiles --CORRECT ANSWER--- moderate temperature loving microbes,
most common type
- (25 deg. C - 40 deg. C)
- these are human pathogens also include most of the common spoilage and
disease organisms.
- ex: 37 deg. C (the optimum temp. for many pathogenic bacteria)
thermophiles --CORRECT ANSWER--- heat loving microbes
- (40 deg. C - 70 deg. C)
- many can't grow at temps below 45 deg. C
- hyperthermophiles = (70 deg. C - 110 deg. C)
what temperature do pathogens grow at? --CORRECT ANSWER--- human
body temp. (37 degrees celsius)
Page 1 of 28
,what pH range do most bacteria grow best in? --CORRECT ANSWER--- a
narrow pH range
- neutral (6.5 - 7.5)
- very few grow below pH 4
- foods with low pH (cheese, pickles..) don't spoil easily)
What are some examples of bacteria that grow below pH 4? --CORRECT
ANSWER--- sulfur oxidizers
- H. pylori
____ have more H+ than ______ --CORRECT ANSWER--acids, bases
what is the osmotic pressure inside bacterial cells in an isotonic solution? --
CORRECT ANSWER--- 0.85% NaCl
What type of solution inhibits bacterial growth? --CORRECT ANSWER---
hypertonic solutions (solutes are higher outside the cell)
- water leaves the cell
Why do we study microbial growth? --CORRECT ANSWER--1) to prove what
causes disease
Page 2 of 28
, 2) for antibiotic susceptibility (how to kill)
3) for research
what are the physical aspects of microbial growth? --CORRECT ANSWER---
temperature
- pH
- osmotic pressure
what are the 3 main groups microbes are classified into based on their optimum
temperature? --CORRECT ANSWER--1) psychrophiles
2) mesophiles
3) thermophiles
psychrophiles --CORRECT ANSWER--- cold loving microbes
- don't cause disease
- (-10 deg. C to 20 deg. C)
what is plasmolysis? --CORRECT ANSWER--- the osmotic loss of water from
the cell in a hypertonic environment
- shrinkage of the cell plasma membrane - die
Page 3 of 28
