Micro Exam 2

Which of the following microbial systems are most commonly exploited to control the growth of microorganisms?

Microbial nutrition

Which of the following best defines biocides?

The term biocide describes all antimicrobials that can be used to control microbes

Which three of the following are microbial cell types that are especially recalcitrant to control agents?

Bacterial endospores, Protozoan cysts, & Mycobacterium spp

Which two of the following may be found on a properly disinfected object?

Small number of microbes & Viable spores

How do bacteristatic and bactericidal treatments differ?

Bacteristatic treatments prevent growth while bactericidal treatments kill

Which two of the following are effective ways to inhibit the growth of microorganisms?

Poisoning & Starvation

Choose three commonly used physical methods for sterilization

Filtration, Heat, & Radiation

The terminology used to describe different microbial control agents is important to understand because ___

some of the words are in common use with imprecise meanings & some treatments have different effects depending on the conditions

Which of the following statements regarding control of microbial cell types is false?

Bacterial endospores are challenging to control because they reside inside the mother cell

Filtration is an effective means of sterilization for liquid solutions. Its effect on microorganisms is to ___

remove them from the solution

How do sterilization and disinfection differ?

A sterile object has no living cells, spores, or viruses while a disinfected object may have small numbers of these

Boiling water is best described as which of the following?

Disinfectant

Growth of microbes will resume following the discontinuation of which type of treatment?

Fungistatic & Bacteriostatic

What temperature of moist heat will eliminate most bacterial endospores?

Temperatures above 100°C

Heat and radiation are examples of which type of method for the control of microbes?

Physical

Which of the following is a limitation on the use of ultraviolet radiation for sterilization?

It does not penetrate substances effectively

Which of the following best defines biocides?

The term biocide describes all antimicrobials that can be used to control microbes

Which two of the following chemical control agents are used to reliably control bacterial endospores?

Formaldehyde & Ethylene oxide

Filtration is an effective means of sterilization for which two of the following?

Chemical solutions & Gases

What are the primary mechanisms of action of phenolics as disinfectants?

Disrupt cell membranes & Denature proteins

Which of the following would not be killed by a treatment of boiling for 10 minutes?

Bacterial endospores

The primary mechanisms of action of alcohols on bacterial cells are to ___

dissolve membrane lipids & denature proteins

The device used for steam sterilization in a microbiology lab is the ___

autoclave

Which one of the following halogens is used as an antiseptic?

Iodine

Which items are best sterilized by exposure to UV radiation?

Laboratory work surfaces

What are the primary mechanisms of action of ethylene oxide gas as a sterilizing agent?

Alkylates nucleic acids & Alkylates proteins

Which of the following chemical control agents are safe for use on human skin?

Benzalkonium chloride

Which of the following statements is correct regarding the influence of population size on the effectiveness of an antimicrobial agent?

A larger population requires a longer treatment time to be killed than a smaller population

Which two of these are advantages of phenolics as disinfectants?

They are active in the presence of organic material & They are active long after application

Which is more effective at killing bacteria?

70% ethanol (in water)

Which of the following statements is correct about the use of alcohols as chemical control agents?

Ethanol and isopropanol are the most commonly used agents

What change in microbial population size is reasonable to achieve sterilization?

A million times fewer microbes

What is the primary mechanism of action of halogens against microbial cells?

Oxidizes cell constituents

Which of the following statements regarding biological control of microorganisms is correct?

Human application of biological control mechanisms is relatively new

Which two of the following terms describe the effects of sterilizing gases on microbial cells?

Sporicidal & Microbicidal

The first true antibiotic (a natural microbial product) to be used was ___

Penicillin

How is cell death related to the time of exposure to an antimicrobial agent?

An equal fraction of the population is killed in each time interval

A successful antimicrobial agent has the ability to kill or inhibit microbial pathogens with little or no damage to the host, a property called ___

Selective toxicity

Which of the following statements is correct regarding the influence of concentration on the effectiveness of an antimicrobial agent?

The effectiveness of an antimicrobial agent is not always related to its concentration

Drugs that are effective against a wide variety of pathogens are called ___

broad-spectrum

Which of the following statements is correct regarding the influence of contact time on the effectiveness of an antimicrobial agent?

A longer exposure results in more killing

Dilution susceptibility tests can be used to determine both minimal ___ concentration and minimal ___ concentration

inhibitory & lethal

Which two of the following may be considered types of biological control?

Virus infection & Bacterial predation

The most selective antibiotics in use target the bacterial ___

Cell wall

Penicillin is considered to be the first true antibiotic, meaning that it ___

is a natural microbial product

The therapeutic index of a protein synthesis inhibitor is less than the therapeutic index of a cell wall inhibitor because…

bacterial cells and host cells both use ribosomes for protein synthesis

The ability to kill or inhibit microbial pathogens while causing minimal damage to the host is called…

selective toxicity

A substance that blocks the functioning of a specific biochemical pathway is called a(n)

antimetabolite

The sulfonamides inhibit the growth of a wide variety of bacteria and are classified as ___ drugs

Broad-spectrum

Which two of the following are NOT targets of antibacterial drugs that inhibit nucleic acid synthesis?

Dihydrofolate reductase & DNA ligase

The dilution susceptibility test can be used to determine the ___ concentration

minimal inhibitory & minimal lethal

The most selective antibiotics target ___

cell wall synthesis

Which of the following statements concerning antivirals is false?

Antivirals are often referred to as antibiotics

The therapeutic index of a protein synthesis inhibitor is ___ the therapeutic index of a cell wall inhibitor

less than

Why are there fewer antifungal drugs than antibacterial drugs?

Fungal cells are more similar to human cells than bacterial cells

An antimicrobial substance that antagonizes or blocks the function of a specific biochemical pathway is a(n)

Antimetabolite

The side effects and toxicity of antiprotozoan drugs results from the fact that protozoans and humans are both members of Domain ___ and have similar enzymes, processes, and pathways

Eukarya

Which two of the following are targets of antibacterial drugs that inhibit nucleic acid synthesis?

RNA polymerase & Topoisomerase

Antiviral agents are ___ referred to as "antibiotics."

never

Regarding cell types and antimicrobial agents, which two of the following statements are true?

Currently there are fewer antifungal agents than antibacterial agents & Fungal cells are more similar to human cells than to bacterial cells

The side effects and toxicity of antiprotozoan drugs in humans is primarily due to ___

the drugs targeting protozoan enzymes and processes also present in human cells

The substantial reduction of the total population of microorganisms on inanimate objects and the destruction of potential pathogens is called ________.

disinfection

The destruction or removal of all viable organisms is called ________.

sterilization

Which of the following inhibits bacterial growth but does not kill bacteria?

Bacteriostatic agent

An agent that specifically kills fungi but not other kinds of microorganisms is also known as a ________.

fungicidal agent

Which of the following is MOST effective against resistant endospores?

Autoclaving

Which kind of sterilization procedure takes advantage of the size of microorganisms?

Filtration

Which of the following is not a method of heat sterilization?

Pasteurization

Ultraviolet radiation is an effective means of sterilizing surfaces

true

Match the following chemical control agent

• Surfactants

Amphipathic organic molecules that serve as disinfectants by disrupting membranes

Match the following chemical control agent

• Chlorine

The disinfectant of choice for municipal water supplies

Match the following chemical control agent

• Isopropanol

An important alcohol germicide

Match the following chemical control agent

• Iodine

An effective skin antiseptic that may cause skin damage, staining, and allergies

Which of the following influence(s) the efficiency of an antimicrobial agent?

All of the above

Bacterial pathogens may be controlled by ________, which are viruses that specifically infect and lyse the bacterial host.

Bacteriophages

The lowest concentration of an antibiotic that prevents growth is the ________.

minimal inhibitory concentration (MIC)

The most selectively toxic antibacterial agents are those that interfere with bacterial cell wall synthesis. This is because ________.

bacterial cell walls have a unique structure not found in eukaryotic host cells

The minimum lethal concentration (MLC) is the lowest concentration of drug from which organisms fail to recover when removed from the drug.

true

Which of the following does not inhibit protein synthesis?

Penicillin

Which of the following is normally treated by antifungal creams and solutions?

Superficial mycoses

Drugs chloroquine and qualaquin when used to treat malaria are examples of ________.

antiprotozoan drugs

Which of the following is the major reason why it has been difficult to treat viral infections with chemotherapeutic agents?

Viruses use the metabolic machinery of their hosts, which limits many of the potential points of attack

Sulfonamides and other drugs that inhibit folic acid synthesis are considered _______________.

metabolic antagonist

Treatment of fungal infections is more difficult than treatment of bacterial infections because the greater metabolic similarity between the fungi and their hosts limits the ability of a drug to have a selective toxicity.

true

The antiviral drugs currently approved for use in HIV disease include ________.

All of the above

Which of the following is normally treated by antifungal creams and solutions?

Superficial mycoses

Select statements representing features that are common to all types of metabolism

All of the above

As shown, this molecule is called ___. If you removed a phosphate group from this compound, then you would be left with ___

ATP; ADP

The bracket indicates the presence of three ___ in the ATP molecule shown

phosphate groups

ATP is formed from energy made available in which of the following processes?

ADP + Pi → ATP

All of the above

Match the outcome of oxidation-reduction reactions with the correct description

• Electron donor

Becomes less energy rich after a redox reaction

Match the outcome of oxidation-reduction reactions with the correct description

• Electron acceptor

Becomes more energy rich after a redox reaction

Which of the following are features common to all types of metabolism?

Redox reactions play a critical role in energy conservation & Energy is most often conserved in molecules called ATP

Each redox reaction consists of two half-reactions. The acceptor and donor of a half reaction are referred to as a(n) ___ redox pair

conjugate

The common acronym for this compound is ___

ATP (Adenosine Triphosphate)

Standard reducing potentials generally couple reactions that have negative potentials with reactions that have ___ potentials.

positive

How many phosphate groups are present in ATP?

three

Carbon dioxide donates electrons to the electron transport chain.

false

When ATP is hydrolyzed to ADP and Pi, the energy released powers which of the following kinds of work?

1. Transport work

2. Mechanical work

3. Chemical work

4. Substrate level phosphorylation

1, 2, & 3

When NADH donates electrons to the first carrier in the electron transport chain, NADH becomes ___ and the first carrier becomes ___. The first carrier then donates electrons to the second carrier, becoming ___ and available to accept more electrons.

oxidized; reduced; oxidized