GCSU Bachoon Microbiology Test 2 Exam
(2025/2026) – Actual Exam with
Complete Questions | Comprehensive
Microbiology Assessment
Why do we study microbial growth? -CORRECTANSWER 1) to prove what causes
disease
2) for antibiotic susceptibility (how to kill)
3) for research
what are the physical aspects of microbial growth? -CORRECTANSWER - temperature
- pH
- osmotic pressure
what are the 3 main groups microbes are classified into based on their optimum
temperature? -CORRECTANSWER 1) psychrophiles
2) mesophiles
3) thermophiles
psychrophiles -CORRECTANSWER - cold loving microbes
- don't cause disease
- (-10 deg. C to 20 deg. C)
,what is a psychrotroph? -CORRECTANSWER - organism that is capable of growth
between 0 deg. C and 30 deg. C
mesophiles -CORRECTANSWER - 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 -CORRECTANSWER - 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? -CORRECTANSWER - human body temp.
(37 degrees celsius)
what pH range do most bacteria grow best in? -CORRECTANSWER - 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? -CORRECTANSWER -
sulfur oxidizers
- H. pylori
____ have more H+ than ______ -CORRECTANSWER acids, bases
what is the osmotic pressure inside bacterial cells in an isotonic solution? -
CORRECTANSWER - 0.85% NaCl
What type of solution inhibits bacterial growth? -CORRECTANSWER - hypertonic
solutions (solutes are higher outside the cell)
- water leaves the cell
what is plasmolysis? -CORRECTANSWER - the osmotic loss of water from the cell in a
hypertonic environment
- shrinkage of the cell plasma membrane - die
What causes high osmotic pressure and can be used to preserve food? -
CORRECTANSWER - salt or sugar
- causes plasmolysis
ex: salted meat, jams, jelly
(2025/2026) – Actual Exam with
Complete Questions | Comprehensive
Microbiology Assessment
Why do we study microbial growth? -CORRECTANSWER 1) to prove what causes
disease
2) for antibiotic susceptibility (how to kill)
3) for research
what are the physical aspects of microbial growth? -CORRECTANSWER - temperature
- pH
- osmotic pressure
what are the 3 main groups microbes are classified into based on their optimum
temperature? -CORRECTANSWER 1) psychrophiles
2) mesophiles
3) thermophiles
psychrophiles -CORRECTANSWER - cold loving microbes
- don't cause disease
- (-10 deg. C to 20 deg. C)
,what is a psychrotroph? -CORRECTANSWER - organism that is capable of growth
between 0 deg. C and 30 deg. C
mesophiles -CORRECTANSWER - 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 -CORRECTANSWER - 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? -CORRECTANSWER - human body temp.
(37 degrees celsius)
what pH range do most bacteria grow best in? -CORRECTANSWER - 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? -CORRECTANSWER -
sulfur oxidizers
- H. pylori
____ have more H+ than ______ -CORRECTANSWER acids, bases
what is the osmotic pressure inside bacterial cells in an isotonic solution? -
CORRECTANSWER - 0.85% NaCl
What type of solution inhibits bacterial growth? -CORRECTANSWER - hypertonic
solutions (solutes are higher outside the cell)
- water leaves the cell
what is plasmolysis? -CORRECTANSWER - the osmotic loss of water from the cell in a
hypertonic environment
- shrinkage of the cell plasma membrane - die
What causes high osmotic pressure and can be used to preserve food? -
CORRECTANSWER - salt or sugar
- causes plasmolysis
ex: salted meat, jams, jelly
