MICR 271 - MODULE 3,4 Practice
Questions and All Correct Answers 2026
Updated.
How do bacterial populations divide? - Answer Binary fission.
1. Chromosome replication
2. Continued growth
3. Division into two daughter cells.
What is one of the proposed ways PG layers grow? - Answer Osmotic pressure exerted by the
cytosol on the PG.
What are some of the ways bacteria become old? - Answer 1. Inherit damaged DNA, damaged
proteins, or old cell material at the "old pole"
2. Activation of defense systems (M) rather than growth systems (G)
What is metabolism? - Answer The sum of chemical reactions occurring within a system to
ensure its survival.
What is anabolism? - Answer The building structures necessary for survival (proteins, DNA...)
What is catabolism? - Answer The breaking down of structures necessary for energy
What are the different conditions which affect bacterial growth? - Answer 1. Temperature, pH,
pressure, water availability: All have an impact on enzymatic activity. Can denature.
2. Oxygen levels
What are the different bacterial species in relation to oxygen concentration necessity? - Answer
Obligate aerobes: Aerobic respiration. O is the terminal electron acceptor.
Facultative anaerobe: Doesn't need O, but grows better with it.
Aerotolerant anaerobe: Can tolerate O but doesn't use it to grow. Strictly fermentative
metabolism.
Strict anaerobe: O is toxic. Fermentation or anaerobic respiration.
Microaerophiles: Damaged by too much oxygen (20% in atmosphere) but need 2-10% O.
,How do Reactive Oxygen Species come to be, and what are they? - Answer Proteins transfer
electrons from oxygen, making it unstable. ROS can damage DNA and important molecules
within the body. These include peroxide, hydroxyl radicals, and more.
What are all required nutrients for living organisms? - Answer Central: Carbon
(photosynthesis, prokaryotic breakdown) and nitrogen (nitrifying bacteria turn NH3 to NO2 or
NO3).
Minor: Vitamins, Hydrogen, Trace elements (other chemical compounds found in small
concentrations within the organism).
What are the 3 factors which differentiate bacteria? - Answer 1. Energy source.
2. Carbon source.
3. Electron source.
What are the different energy sources? - Answer 1. Chemotropic: Energy obtained from
external chemical compounds.
2. Phototropic: Energy obtained from light.
What are the different carbon sources? - Answer 1. Autotrophic: Acquire carbon from carbon
dioxide
2. Heterotropic: Acquire carbon from organic compounds
3. Mixotrophs: Acquire carbon from both carbon dioxide and organic compounds.
What are the different electron sources? - Answer 1. Lithotrophic: Reduction from inorganic
compouds.
2. Organitrophic: Organic compounds.
What are the different combinations or energy and carbon sources that can exist? - Answer 1.
Photoautotroph: Plants! They use the sun's light as energy and obtain carbon from carbon
dioxide in the environment.
2. Photoheterotroph: Green/purple non-sulfur bacteria.
3. Chemoautotroph: Hydrogen, sulfur, nitrifying bacteria + some archaea
4. Chemoheterotroph:
A) Aerobic: Fungi, pathogenic bacteria
B) Anaerobic: Protozoa, bacteria, archaea.
What are persister cells? - Answer Microbes capable of adapting quickly to a change in
environment. They do so by producing a minimal amount of ATP to survive, but not to grow.
, This makes them harder to recognize by antibiotics because antibiotics usually target metabolic
intermediates.
What are different ways of producing ATP? - Answer 1. Respiration
2. Fermentation
What is quorum sensing? - Answer the ability of bacteria in a biofilm to communicate with
each other and coordinate their activities
What are autoinducers? - Answer Signalling molecules produced and secreted by quorum
sensing bacteria. They change a bacterium's gene expression when at threshold concentrations.
How is quorum sensing accomplished in a gram positive cell? - Answer Autoinducer binds to a
receptor outside of the cell which then activates a cascade and alters gene expression.
How is quorum sensing accomplished in gram negative bacteria? - Answer Autoinducer is
taken into the cell, binds to an intracellular receptor and acts as a transcriptional regulator.
What can autoinducers activate? - Answer 1. Biofilm formation
2. Toxin production
3. Motility
What is it somewhat inacurrate to grow species in a lab setting? - Answer 1. Hard to recreate
exact conditions.
2. Labs often have an excess of nutrients
3. Labs don't have the species variety that the environment does.
4. Labs don't have the symbiotic interactions that they experience in the environment.
What are the steps to culturing bacteria? - Answer 1. A frozen culture is streaked onto an agar
nutrient plate (sufficient nutrients)
2. After 16-24 hours, colonies (each originating from a single bacterium) should arise.
3. Colony is mixed into 3-5 mL of media. The number of bacteria is determined by ocular
density.
4. Added to 50-over 1000mL of liquid medium. Rotation allows for oxygen to come into contact
with the bacteria. Here, the growth rate can be determined.
What are the different phases of bacterial culture growth? - Answer 1. Lag phase: The
organisms are getting used to the conditions and adapting. There is very little division.
Questions and All Correct Answers 2026
Updated.
How do bacterial populations divide? - Answer Binary fission.
1. Chromosome replication
2. Continued growth
3. Division into two daughter cells.
What is one of the proposed ways PG layers grow? - Answer Osmotic pressure exerted by the
cytosol on the PG.
What are some of the ways bacteria become old? - Answer 1. Inherit damaged DNA, damaged
proteins, or old cell material at the "old pole"
2. Activation of defense systems (M) rather than growth systems (G)
What is metabolism? - Answer The sum of chemical reactions occurring within a system to
ensure its survival.
What is anabolism? - Answer The building structures necessary for survival (proteins, DNA...)
What is catabolism? - Answer The breaking down of structures necessary for energy
What are the different conditions which affect bacterial growth? - Answer 1. Temperature, pH,
pressure, water availability: All have an impact on enzymatic activity. Can denature.
2. Oxygen levels
What are the different bacterial species in relation to oxygen concentration necessity? - Answer
Obligate aerobes: Aerobic respiration. O is the terminal electron acceptor.
Facultative anaerobe: Doesn't need O, but grows better with it.
Aerotolerant anaerobe: Can tolerate O but doesn't use it to grow. Strictly fermentative
metabolism.
Strict anaerobe: O is toxic. Fermentation or anaerobic respiration.
Microaerophiles: Damaged by too much oxygen (20% in atmosphere) but need 2-10% O.
,How do Reactive Oxygen Species come to be, and what are they? - Answer Proteins transfer
electrons from oxygen, making it unstable. ROS can damage DNA and important molecules
within the body. These include peroxide, hydroxyl radicals, and more.
What are all required nutrients for living organisms? - Answer Central: Carbon
(photosynthesis, prokaryotic breakdown) and nitrogen (nitrifying bacteria turn NH3 to NO2 or
NO3).
Minor: Vitamins, Hydrogen, Trace elements (other chemical compounds found in small
concentrations within the organism).
What are the 3 factors which differentiate bacteria? - Answer 1. Energy source.
2. Carbon source.
3. Electron source.
What are the different energy sources? - Answer 1. Chemotropic: Energy obtained from
external chemical compounds.
2. Phototropic: Energy obtained from light.
What are the different carbon sources? - Answer 1. Autotrophic: Acquire carbon from carbon
dioxide
2. Heterotropic: Acquire carbon from organic compounds
3. Mixotrophs: Acquire carbon from both carbon dioxide and organic compounds.
What are the different electron sources? - Answer 1. Lithotrophic: Reduction from inorganic
compouds.
2. Organitrophic: Organic compounds.
What are the different combinations or energy and carbon sources that can exist? - Answer 1.
Photoautotroph: Plants! They use the sun's light as energy and obtain carbon from carbon
dioxide in the environment.
2. Photoheterotroph: Green/purple non-sulfur bacteria.
3. Chemoautotroph: Hydrogen, sulfur, nitrifying bacteria + some archaea
4. Chemoheterotroph:
A) Aerobic: Fungi, pathogenic bacteria
B) Anaerobic: Protozoa, bacteria, archaea.
What are persister cells? - Answer Microbes capable of adapting quickly to a change in
environment. They do so by producing a minimal amount of ATP to survive, but not to grow.
, This makes them harder to recognize by antibiotics because antibiotics usually target metabolic
intermediates.
What are different ways of producing ATP? - Answer 1. Respiration
2. Fermentation
What is quorum sensing? - Answer the ability of bacteria in a biofilm to communicate with
each other and coordinate their activities
What are autoinducers? - Answer Signalling molecules produced and secreted by quorum
sensing bacteria. They change a bacterium's gene expression when at threshold concentrations.
How is quorum sensing accomplished in a gram positive cell? - Answer Autoinducer binds to a
receptor outside of the cell which then activates a cascade and alters gene expression.
How is quorum sensing accomplished in gram negative bacteria? - Answer Autoinducer is
taken into the cell, binds to an intracellular receptor and acts as a transcriptional regulator.
What can autoinducers activate? - Answer 1. Biofilm formation
2. Toxin production
3. Motility
What is it somewhat inacurrate to grow species in a lab setting? - Answer 1. Hard to recreate
exact conditions.
2. Labs often have an excess of nutrients
3. Labs don't have the species variety that the environment does.
4. Labs don't have the symbiotic interactions that they experience in the environment.
What are the steps to culturing bacteria? - Answer 1. A frozen culture is streaked onto an agar
nutrient plate (sufficient nutrients)
2. After 16-24 hours, colonies (each originating from a single bacterium) should arise.
3. Colony is mixed into 3-5 mL of media. The number of bacteria is determined by ocular
density.
4. Added to 50-over 1000mL of liquid medium. Rotation allows for oxygen to come into contact
with the bacteria. Here, the growth rate can be determined.
What are the different phases of bacterial culture growth? - Answer 1. Lag phase: The
organisms are getting used to the conditions and adapting. There is very little division.
