BIOLOGY 2402 - EXAM 2 QUESTIONS AND ANSWERS LATEST
UPDATES 2026 WITH CORRECT ANSWERS 100% WITH COMPLETE
SOLUTIONS PASS GUARANTEED | GRADED A+ |
Define the terms for microbial control methods - ANSWER-Biocide - all antimicrobial
agents used to control microorganisms (chemical, physical, mechanical, or
biological)
Sterilization - all living cells, spores, and acellular entities are destroyed or removed
from an object
Disinfection - killing, inhibiting, or removing microorganisms that might cause
disease on inanimate object
Sanitization - microbe populations are lowered to levels that are safe for public
health standards, partially disinfect
Antisepsis - destruction or inhibition of microorganisms on living tissue
Chemotherapy - generic term that describes application of chemicals to kill
microorganisms
What is a death curve? What is it used to determine? - ANSWER-A graphical
representation showing how a population of microorganisms responds to exposure
to a lethal agent, like disinfectants or antimicrobial agents. It is used to assess the
effectiveness of these agents in killing or inactivating microorganisms. Microbes do
not instantly die after being exposed to a lethal agent, population is reduced
exponentially at constant intervals.
How can you remove microbes using mechanical methods? - ANSWER-Filtration -
using physical barriers like filters with specific pore sizes to trap and remove
microorganisms from liquids or gases.
Centrifugation - spinning samples in a centrifuge to separate microbes from a liquid
based on their density and size.
,Ultrasonication - the use of high-frequency sound waves to disrupt microbial cells,
causing them to break apart.
Heat - applying high temperatures, such as pasteurization or autoclaving, to kill or
inactivate microorganisms.
Mechanical agitation - using physical force, like stirring or shaking, to dislodge and
detach microbes from surfaces.
Scrubbing and brushing - physically scrubbing surfaces or objects to remove
adherent microorganisms, often used in cleaning and sanitation processes.
Ultraviolet (UV) radiation - exposing microbes to UV light, which damages their DNA
and renders them unable to reproduce.
Pressure washing - using high-pressure water jets to remove microbes from surfaces,
especially in cleaning and sanitation applications
What are physical methods to control microbial growth? - ANSWER-Filtration - used
to reduce microbial populations in heat-sensitive solutions, can be used to sterilize
liquids and gases by acting as a barrier but does not kill microbes, membrane filters,
air filters (n95 mask), laminar flow hoods
Heat - moist heat can destroy cells and viruses, degrades proteins, nucleic acids,
and the plasma membrane of microbe, autoclave is a device that uses saturated
steam pressure and hot enough to destroy endospores, dry heat (incineration)
Pasteurization - used on heat-sensitive substances, does not sterilize but does kill
pathogens and slows food spoilage
Ultraviolet radiation - causes thymine-thymine dimers in DNA, prevents replication
and transcription, UV limited to surface sterilization because it does not penetrate
glass, dirt films, water, and other substances
Ionizing (gamma) radiation - sterilizes by penetrating deep into objects
Know the chemical agents we went through and how they destroy microbial cells -
ANSWER-Phenolics - among the earliest antiseptics and disinfectants, introduced by
Joseph Lister in 1867 to reduce infection risks during surgery, still used today in
laboratories and hospitals, work by denaturing proteins and disrupting cell
membranes
, Alcohols - most commonly used disinfectants, antiseptics, and sanitizers, effective
against bacteria, fungi, and some enveloped viruses but not spores. Ethanol and
isopropanol, typically used at 60-80% concentration, work by dissolving membrane
lipids
Halogens - used for disinfection and antiseptic purposes, iodine is effective at killing
microorganisms and some endospores, chlorine commonly in the form of bleach,
highly efficient at destroying bacteria and fungi
Heavy metals - silver and copper have been used as germicides and inactivating
proteins
List the ways we evaluate antimicrobial agent - ANSWER-EPA regulates disinfectants
FDA regulates agents used on humans and animals
1. Population size - larger populations of microbes require longer time to die than
smaller ones
2. Population composition - the nature of the organism impacts the effectiveness of
the agent (endospores more resistant than vegetative cells, younger cells are easier
to destroy than mature ones)
3. Concentration or intensity of an antimicrobial agent - higher concentrations can
sometimes destroy the organisms quicker
4. Contact time - the longer the exposure the more microorganisms will be killed
5. Temperature - higher temperatures enhance chemical activity
6. Local environment - can offer protection or aid in destruction, heat kills better and
faster with an acidic pH, organism matter like biofilms can protect
What are some examples of biological agents used to control microbial growth? -
ANSWER-Emerging science involving the exploitation of natural control processes,
predation of microorganisms, viral-mediated lysis, toxin-mediated killing
In the early 1900s it was discovered that isolating bacteriophages from patients with
dysentery could be used to help fight the disease
UPDATES 2026 WITH CORRECT ANSWERS 100% WITH COMPLETE
SOLUTIONS PASS GUARANTEED | GRADED A+ |
Define the terms for microbial control methods - ANSWER-Biocide - all antimicrobial
agents used to control microorganisms (chemical, physical, mechanical, or
biological)
Sterilization - all living cells, spores, and acellular entities are destroyed or removed
from an object
Disinfection - killing, inhibiting, or removing microorganisms that might cause
disease on inanimate object
Sanitization - microbe populations are lowered to levels that are safe for public
health standards, partially disinfect
Antisepsis - destruction or inhibition of microorganisms on living tissue
Chemotherapy - generic term that describes application of chemicals to kill
microorganisms
What is a death curve? What is it used to determine? - ANSWER-A graphical
representation showing how a population of microorganisms responds to exposure
to a lethal agent, like disinfectants or antimicrobial agents. It is used to assess the
effectiveness of these agents in killing or inactivating microorganisms. Microbes do
not instantly die after being exposed to a lethal agent, population is reduced
exponentially at constant intervals.
How can you remove microbes using mechanical methods? - ANSWER-Filtration -
using physical barriers like filters with specific pore sizes to trap and remove
microorganisms from liquids or gases.
Centrifugation - spinning samples in a centrifuge to separate microbes from a liquid
based on their density and size.
,Ultrasonication - the use of high-frequency sound waves to disrupt microbial cells,
causing them to break apart.
Heat - applying high temperatures, such as pasteurization or autoclaving, to kill or
inactivate microorganisms.
Mechanical agitation - using physical force, like stirring or shaking, to dislodge and
detach microbes from surfaces.
Scrubbing and brushing - physically scrubbing surfaces or objects to remove
adherent microorganisms, often used in cleaning and sanitation processes.
Ultraviolet (UV) radiation - exposing microbes to UV light, which damages their DNA
and renders them unable to reproduce.
Pressure washing - using high-pressure water jets to remove microbes from surfaces,
especially in cleaning and sanitation applications
What are physical methods to control microbial growth? - ANSWER-Filtration - used
to reduce microbial populations in heat-sensitive solutions, can be used to sterilize
liquids and gases by acting as a barrier but does not kill microbes, membrane filters,
air filters (n95 mask), laminar flow hoods
Heat - moist heat can destroy cells and viruses, degrades proteins, nucleic acids,
and the plasma membrane of microbe, autoclave is a device that uses saturated
steam pressure and hot enough to destroy endospores, dry heat (incineration)
Pasteurization - used on heat-sensitive substances, does not sterilize but does kill
pathogens and slows food spoilage
Ultraviolet radiation - causes thymine-thymine dimers in DNA, prevents replication
and transcription, UV limited to surface sterilization because it does not penetrate
glass, dirt films, water, and other substances
Ionizing (gamma) radiation - sterilizes by penetrating deep into objects
Know the chemical agents we went through and how they destroy microbial cells -
ANSWER-Phenolics - among the earliest antiseptics and disinfectants, introduced by
Joseph Lister in 1867 to reduce infection risks during surgery, still used today in
laboratories and hospitals, work by denaturing proteins and disrupting cell
membranes
, Alcohols - most commonly used disinfectants, antiseptics, and sanitizers, effective
against bacteria, fungi, and some enveloped viruses but not spores. Ethanol and
isopropanol, typically used at 60-80% concentration, work by dissolving membrane
lipids
Halogens - used for disinfection and antiseptic purposes, iodine is effective at killing
microorganisms and some endospores, chlorine commonly in the form of bleach,
highly efficient at destroying bacteria and fungi
Heavy metals - silver and copper have been used as germicides and inactivating
proteins
List the ways we evaluate antimicrobial agent - ANSWER-EPA regulates disinfectants
FDA regulates agents used on humans and animals
1. Population size - larger populations of microbes require longer time to die than
smaller ones
2. Population composition - the nature of the organism impacts the effectiveness of
the agent (endospores more resistant than vegetative cells, younger cells are easier
to destroy than mature ones)
3. Concentration or intensity of an antimicrobial agent - higher concentrations can
sometimes destroy the organisms quicker
4. Contact time - the longer the exposure the more microorganisms will be killed
5. Temperature - higher temperatures enhance chemical activity
6. Local environment - can offer protection or aid in destruction, heat kills better and
faster with an acidic pH, organism matter like biofilms can protect
What are some examples of biological agents used to control microbial growth? -
ANSWER-Emerging science involving the exploitation of natural control processes,
predation of microorganisms, viral-mediated lysis, toxin-mediated killing
In the early 1900s it was discovered that isolating bacteriophages from patients with
dysentery could be used to help fight the disease
