MCB 2004 EXAM 2 QUESTIONS WITH VERIFIED
ANSWERS
Alkaliphiles grow best at which pH values? - Answers - 9-11
A mature biofilm experiences decreased nutrient concentrations. Bacteria in this biofilm
will begin producing enzymes that (A) ____ exopolysaccharides. The bacteria also (B)
_____ flagella. - Answers - Break down , gain
Which type of microorganism cannot survive in the presence of oxygen? - Answers -
Obligate anaerobes
How will the enzymes of thermophilic bacteria fare at human body temperature (37ºC)?
- Answers - The enzymes will function more slowly than usual.
Which colony represents bacteria that ferment lactose on MacConkey agar? - Answers -
Lactose fermenters (red circle)
What is the name for microbes that can survive at temperatures of 50º to 80ºC? -
Answers - Thermopylae
Nitrogen is removed from air and converted into ammonia - Answers - Nitrogen fixers
Ammonia is converted to nitrate - Answers - Nitrofires
Nitrogen is removed from nitrate and converted to nitrogen gas - Answers - Denitrifiers
Identify the stages of biofilm formation shown on the image below. - Answers - 1.
Flagella attach to mono layer
2. Micro colonies form
3. Cell produce EPS
4. Biofilm matures
5. Biofilm dissolves
Which characteristic of the machine shown below makes it a good model system for the
gastrointestinal tract? - Answers - It contains a continuous culture
Which of the following statements about biofilms is false?
A. Biofilms cause dental plaque.B. Biofilms can form on rocks.C. Biofilms are very
sensitive to antibiotics.D. Biofilms on medical implants can cause infections. - Answers -
C
, A bacterium is grown at temperatures slightly below optimum. How will this change the
shape of the growth curve? - Answers - The slope of log phase will be less steep.
MacConkey agar is both selective and differential. What makes it differential? - Answers
- Lactose
Which of the following are advantages of endospores? - Answers - Endospores are
more resistant to dry conditions than vegetative cells are.
B. Endospores are more resistant to environmental toxins than vegetative cells are.
Bacteria enter a cut on a person's hand. The infection will take some time to become
noticeable because the bacteria are in which phase? - Answers - Lag phase
What is the difference between facultative anaerobes and aerotolerant anaerobes? -
Answers - Facultative anaerobes can both respire and ferment, whereas aerotolerant
anaerobes only ferment.
A cell that uses an organic carbon source and obtains energy from light would be called
which of the following? - Answers - Photoheterotroph
Two major types of molecules donate electrons to O2: organic and inorganic. A microbe
using the type of metabolism that involves NADH as the electron donor is called a/an -
Answers - Organotroph
The breakdown stage of metabolism is called catabolism, and the biosynthetic stage of
metabolism is called - Answers - Anabolism
Which of the following best relates entropy to the life of the microbial cell? - Answers -
Cells generally decrease internal entropy and increase external entropy levels.
The name of the process by which nitrogen gas is converted into ammonia is called (A)
______
, and only some microbes are capable of this energetically expensive anaerobic
process. Once ammonia is formed, its incorporation into an organic structure is called
(B) _____ - Answers - N-fixation
assimiliation
The pocket of membrane where the light-harvesting pigment systems are located is
called the (A)____membrane. How many different "types" of photosystems are involved
in photosynthesis? (B) ____.) - Answers - Thylakoid
2
During oxygenic photosynthesis, the O2 that is released comes from - Answers - H2O
Sort these terminal electron acceptors as participating in either aerobic or anaerobic
respiration. - Answers - Aerobic - O2
ANSWERS
Alkaliphiles grow best at which pH values? - Answers - 9-11
A mature biofilm experiences decreased nutrient concentrations. Bacteria in this biofilm
will begin producing enzymes that (A) ____ exopolysaccharides. The bacteria also (B)
_____ flagella. - Answers - Break down , gain
Which type of microorganism cannot survive in the presence of oxygen? - Answers -
Obligate anaerobes
How will the enzymes of thermophilic bacteria fare at human body temperature (37ºC)?
- Answers - The enzymes will function more slowly than usual.
Which colony represents bacteria that ferment lactose on MacConkey agar? - Answers -
Lactose fermenters (red circle)
What is the name for microbes that can survive at temperatures of 50º to 80ºC? -
Answers - Thermopylae
Nitrogen is removed from air and converted into ammonia - Answers - Nitrogen fixers
Ammonia is converted to nitrate - Answers - Nitrofires
Nitrogen is removed from nitrate and converted to nitrogen gas - Answers - Denitrifiers
Identify the stages of biofilm formation shown on the image below. - Answers - 1.
Flagella attach to mono layer
2. Micro colonies form
3. Cell produce EPS
4. Biofilm matures
5. Biofilm dissolves
Which characteristic of the machine shown below makes it a good model system for the
gastrointestinal tract? - Answers - It contains a continuous culture
Which of the following statements about biofilms is false?
A. Biofilms cause dental plaque.B. Biofilms can form on rocks.C. Biofilms are very
sensitive to antibiotics.D. Biofilms on medical implants can cause infections. - Answers -
C
, A bacterium is grown at temperatures slightly below optimum. How will this change the
shape of the growth curve? - Answers - The slope of log phase will be less steep.
MacConkey agar is both selective and differential. What makes it differential? - Answers
- Lactose
Which of the following are advantages of endospores? - Answers - Endospores are
more resistant to dry conditions than vegetative cells are.
B. Endospores are more resistant to environmental toxins than vegetative cells are.
Bacteria enter a cut on a person's hand. The infection will take some time to become
noticeable because the bacteria are in which phase? - Answers - Lag phase
What is the difference between facultative anaerobes and aerotolerant anaerobes? -
Answers - Facultative anaerobes can both respire and ferment, whereas aerotolerant
anaerobes only ferment.
A cell that uses an organic carbon source and obtains energy from light would be called
which of the following? - Answers - Photoheterotroph
Two major types of molecules donate electrons to O2: organic and inorganic. A microbe
using the type of metabolism that involves NADH as the electron donor is called a/an -
Answers - Organotroph
The breakdown stage of metabolism is called catabolism, and the biosynthetic stage of
metabolism is called - Answers - Anabolism
Which of the following best relates entropy to the life of the microbial cell? - Answers -
Cells generally decrease internal entropy and increase external entropy levels.
The name of the process by which nitrogen gas is converted into ammonia is called (A)
______
, and only some microbes are capable of this energetically expensive anaerobic
process. Once ammonia is formed, its incorporation into an organic structure is called
(B) _____ - Answers - N-fixation
assimiliation
The pocket of membrane where the light-harvesting pigment systems are located is
called the (A)____membrane. How many different "types" of photosystems are involved
in photosynthesis? (B) ____.) - Answers - Thylakoid
2
During oxygenic photosynthesis, the O2 that is released comes from - Answers - H2O
Sort these terminal electron acceptors as participating in either aerobic or anaerobic
respiration. - Answers - Aerobic - O2
