Microbio exam 2 old exam questions

Discuss the metabolic diversity seen in microbes.

Photoautotrophs: use energy from sunlight to make organic compounds from CO2 in the atmosphere. Photoheterotrophs: use energy of sunlight and obtain their carbon from organic compounds. Chemolithotrophs: use inorganic compounds for energy and obtain their carbon from CO2. Chemoorganotrophs: use organic compounds for both energy and carbon.

Describe the results of Frederick Griffith's experiment.

-Heat killed S strain and living R strain killed the mouse -concluded that R strain was "transformed"

Microbial death rates may be affected by _____. A) pH. B) temperature. C) the presence of organics. D) growth in a biofilm. E) All of the answer choices are correct.

E) All of the answer choices are correct.

What is ionizing radiation? In what situation is it used as a control method?

Radiation that destroys the cells DNA and damages it's cytoplasmic membranes. Used for sterilizing medical equipment and surgical supplies. Can also be used to kill microbes in food like salmonella.

Draw, label, and describe the stages of a bacterial growth curve.

Lag: Cells getting used to environment Log: Cells doubling/ exponentially growing and duplicating Stationary: Growing and death come to an equal Death: decline in cells

Describe catabolism

breaking stuff down for energy

Identify the different byproducts of fermentation? Why are they called by-products and not products?

byproducts are: acids/CO2 and alcohol they are produced as part of process but not the goal. The fermentation goal is to produce the product NAD+.

Which of the following are most resistant to disinfection methods? a) enveloped viruses b) non-enveloped viruses c) endospores

c) endospores

What is the purpose of the calvin cycle? a) to convert light energy into ATP b) to produce oxygen c) to fix inorganic carbon d) to oxidize organic molecules

c) to fix inorganic carbon

Which of the following can occur via lysogenic phages? a)transformation b)generalized transduction c)specialized transduction d)conjugation

c)specialized transduction

What is the final electron acceptor in aerobic respiration?

oxygen

How does moist heat kill microbes? a) ionizes water b) denatures protein c) prevents endospore germination d) breaks covalent bonds

b) denatures proteins

What is a defective phage? A) A virus that has lost some of its genetic material, and therefore cannot infect a new target cell. B) A virus that has lost some of its genetic material, and therefore cannot replicate within a new target cell. C) A virus that lacks the ability to replicate independently of its host cell and cannot survive. D) A virus that cannot attach to its host cell and therefore cannot enter the target cell. E) A virus that lacks a prophage, cannot enter a host cell, and cannot survive.

A) A virus that has lost some of its genetic material, and therefore cannot infect a new target cell.

Which of the following are most resistant to destruction by typical disinfection methods? A) Endospores of Bacillus and Clostridium B) Escherichia C) Enveloped viruses D) Mycoplasma species E) Vegetative bacteria

A) Endospores of Bacillus and Clostridium

Which of the statements below about specialized transduction is false? A) It involves the random transmission of any gene B) It involves the transfer of a few specific genes C) It involves a defective virus D) It only involves genes near the viral DNA integration site E) It involves temperate phages

A) It involves the random transmission of any gene

What are plasmids? A) Self-replicating extra chromosomal DNA B) Pili used for bacterial "sex" C) Bacteria that are antibiotic resistant D) Gene segments that can "jump" from one location in a chromosome to another E) DNA that always contains antibiotic resistance

A) Self-replicating extra chromosomal DNA

Phenols _____. A) denature proteins and destroy cytoplasmic membranes. B) become ineffective in the presence of detergents or organic material. C) such as triclosan have very limited commercial use. D) reliably inactivate all groups of viruses. E) are ineffective against Mycobacterium species.

A) denature proteins and destroy cytoplasmic membranes.

12. Which of the following is a universal process? A) glycolysis B) Krebs cycle C) pentose phosphate pathway D) fermentation E) All of the above.

A) glycolysis

Moist heat kills microorganisms by _____. A) irreversible denaturation of proteins. B) destruction of carbohydrates in the cell wall. C) denaturation of nucleic acids. D) dissolving the capsule. E) destruction of the nuclear envelope.

A) irreversible denaturation of proteins.

The process of killing or removing all of the microorganisms in or on a material is called _____. A) sterilization. B) disinfection. C) sanitation. D) antisepsis. E) degerming.

A) sterilization.

Microwaves do not kill organisms directly but kill by _____. A) the heat they generate in a product. B) generating free radicals. C) generating toxins. D) creating thymine dimers. E) decreasing the pressure in the cells.

A) the heat they generate in a product.

The mechanism by which genes are transferred into bacteria via viruses is called what? A) transduction B) replication C) transformation D) conjugation E) integration

A) transduction

A urine sample with more than 100,000 organisms is considered indicate of infection. A urine sample containing 5000 bacteria with a generation time of 30 minutes sits for three hours before finally being looked at. How many bacteria will be present within the sample? A. 320,000 B. 100,000 C. 64,000 D. 15,000 E. 10,000

A. 320,000

Organisms that are indifferent to the presence of oxygen and do not use it are: A. Aerotolerant anaerobes B. Facultative anaerobes C. Obligate aerobes D. Microaerophiles E. Obligate anaerobes

A. Aerotolerant anaerobes

The simplest technique for isolating bacteria in in growth media is referred to as the: A. Streak-plate method B. Pour-plate method C. Serial dilution method D. MPN method E. Turbity method

A. Streak-plate method

Differentiate between the final electron acceptors for aerobic respiration, anaerobic respiration, and fermentation.

Aerobic respiration: oxygen Anaerobic respiration: nitrate, nitrite or sulfate Fermentation: organic molecule

Who discovered the material responsible for transformation was DNA? A) Watson and Crick B) Avery, MacLeod, and McCarty C) McClintock D) Pasteur E) Semmelweis

B) Avery, MacLeod, and McCarty

Which is true of nosocomial infections? A) They are acquired by susceptible people at various social events. B) They are acquired by susceptible people in the hospital. C) They are acquired by susceptible people at sporting events. D) They occur in communities but very seldom occur in hospitals. E) They occur most frequently in isolated communities.

B) They are acquired by susceptible people in the hospital.

Describe the significance of biofilms.

Biofilms are important for human health because they help treat wastewater and make it clean (bioremediation). They can be detrimental because they are found in our mouths- as plaque. Plaque can then cause us tooth decay and gum disease. They also resist antibiotics as well as our bodies defenses.

Which of the following statements is CORRECT regarding transformation? A) DNA is transferred from one bacterial cell to another by means of a bacteriophage. B) Transformation is the uptake of "naked" DNA from the environment. C) Transformation involves the formation of a sex pilus through which plasmid DNA is shared between bacteria. D) Transformation depends on a donor cell containing an F plasmid and a recipient cell that does not. E) Transformation is a process that depends on physical contact between two bacterial cells.

B) Transformation is the uptake of "naked" DNA from the environment.

Which of the following describes competent cells? A) able to take up naked DNA, can be created in the laboratory, AND are always antibiotic resistant B) able to take up naked DNA, occur naturally, AND can be created in the laboratory C) always antibiotic resistant, are always auxotrophs, AND occur naturally D) can be made in the laboratory, are always antibiotic resistant, AND are always auxotrophs E) able to take up naked DNA, occur naturally, AND are always antibiotic resistant

B) able to take up naked DNA, occur naturally, AND can be created in the laboratory

Oxygen serves as the terminal electron acceptor in which process? A) fermentation B) aerobic respiration C) anaerobic respiration D) pentose phosphate pathway E) glycolysis

B) aerobic respiration

Biochemical reactions that require energy for the conversion of molecular subunits into larger molecules are called _____. A) kinetic energy. B) anabolic reactions. C) catabolic reactions. D) precursor molecules. E) canabolic reactions.

B) anabolic reactions

The linking of N-acetyleglucosamine, N-acetylemuramic acid, and tetrapeptides is a(n) ________ reaction that __________ ATP. A) catabolic; releases B) anabolic; requires C) fermentation; releases D) catabolic; requires E) degradation; releases

B) anabolic; requires

Most enzymes _____. A) are generic, typically recognizing a number of different substrates. B) are specific, typically recognizing a single or a few substrates. C) are active over a wide pH range. D) are active over a wide temperature range. E) are unaffected by heat or acidity.

B) are specific, typically recognizing a single or a few substrates.

Upon treatment with heat or chemicals, bacteria will _____. A) all die immediately. B) die at a constant proportion. C) die at an exponential rate. D) die at a geometric rate. E) always become resistant.

B) die at a constant proportion.

Organisms that use organic molecules as their source of carbon are called _____. A) chemotrophs. B) heterotrophs. C) organoheterotrophs. D) autotrophs. E) organoautotrophs.

B) heterotrophs.

The most important function of nitrites in processed foods is to _____. A) prevent browning. B) inhibit the germination of Clostridium botulinum endospores. C) prevent carcinogen formation. D) make the food more acidic. E) destroy cell membranes of potential pathogens.

B) inhibit the germination of Clostridium botulinum endospores

A sterile item is free of A) microbes, viruses, AND prions. B) microbes, endospores, AND viruses. C) endospores, viruses, AND prions. D) microbes, endospores, AND prions. E) prions only.

B) microbes, endospores, AND viruses.

The name given to the reaction involving removal of electrons or hydrogen atoms from a compound is what? A) glycolysis B) oxidation C) reduction D) metabolism E) respiration

B) oxidation

The characteristics displayed by an organism in any given environment is called its what? A) archaetype B) phenotype C) genotype D) mutatotype E) phenogene

B) phenotype

In photosynthesis, the oxygen originates from which molecule? A) carbon dioxide B) water C) glucose D) hydrogen peroxide E) sulfates

B) water

What is the optimal temperature range for most human pathogens in Celsius? A. 0-4 degrees B. 20-45 degrees C. 35-40 degrees D. 15-25 degrees E. 93-98.6 degrees

B. 20-45 degrees

In the growth curve of a bacterial population the bacteria are rapidly increasing in number in the: A. Lag phase B. Exponential (log) phase C. Stationary phase D. Decline phase E. Death phase

B. Exponential (log) phase

Late log phase of the bacterial growth curve is characterized by: A. Production of primary metabolites B. Production of secondary metabolites C. Transition into death phase D. Decline in cell numbers E. Germination of endospores

B. Production of secondary metabolites

All the bacterial cells that result from the replication of a single original bacterial organism are referred to as: A. Mixed culture B. Pure culture C. Strain D. Species E. Mutant

B. Pure culture

Compare and contrast vertical and horizontal gene transfer. Why/how are both relevant to the rapid rise of "superbug" (bacteria resistant to almost all known antibiotics).

Bacteria are very quick replicators, in vertical gene transfer it takes a generation for the original cell to replicate... in horizontal its even faster. So these replications occur quicker than the antibiotics reaction to them creating a superbug.

DNA transfer by conjugation is more efficient in a liquid medium setting, subjected to very mild agitation (stirring), rather than on an agar plate format. Why? A) Direct cell-to-cell contact is required for this process, and this is more likely to be achieved in the plate format than in the fluid format (especially for relatively non-motile types of bacteria). B) Direct cell-to-cell contact isn't required for this process, so the ability to secrete the DNA into the surrounding fluid medium makes the process more efficient than the dry surface of an agar plate. C) Direct cell-to-cell contact is required for this process, and this is more likely to be achieved in the fluid liquid format than on an agar plate (especially for relatively non-motile types of bacteria). D) Trick question—it can take place with the same degree of efficiency on either format. It doesn't matter! E) Agitation is only needed if the bacteria are non-motile and can't move on a solid medium. Otherwise, it doesn't matter what type of medium is used as long as it contains chemicals to make cells competent.

C) Direct cell-to-cell contact is required for this process, and this is more likely to be achieved in the fluid liquid format than on an agar plate (especially for relatively non-motile types of bacteria).

Fermentation is sometimes used as a means of slowing food spoilage. Why would fermentation lead to this outcome? A) Fermentation is THE process that directly reduces sugars in food. Without sugars, bacteria cannot grow and spoil the food. B) Fermentation will lead to production of high levels of ethanol (95% or higher)—ethanol will kill bacteria. C) Fermentation will lead to production of acidic by-products, dropping the pH of the food below a level that bacteria can tolerate. D) This is a trick question—fermentation actually IS food spoilage and cannot be used to prevent it under any circumstances. E) Fermentation will lead to production of acidic by-products, raising the pH of the food above a level that bacteria can tolerate.

C) Fermentation will lead to production of acidic by-products, dropping the pH of the food below a level that bacteria can tolerate.

Select the FALSE statement regarding hydrogen peroxide. A) It is a sterilant for inanimate objects and is quickly inactivated on living tissue. B) It leaves no toxic residue and is safe on materials such as glass and plastic. C) It is broken down by catalase into water and oxygen. D) It is even more effective when used in combination with peracetic acid. E) It immediately kills all bacteria when applied to a wound.

C) It is broken down by catalase into water and oxygen.

What happens to the carbon molecules in the pyruvic acid that goes through the TCA cycle? A) They get incorporated into cell material. B) They are excreted as waste organic acids. C) They become carbon dioxide. D) They form "energy storage molecules" for the cell. E) They become phosphorylated.

C) They become carbon dioxide.

Which of the following is true regarding antibiotics? A) They cause mutations to occur. B) They may act as mutagens. C) They provide an environment in which preexisting mutants survive. D) They increase the rate of spontaneous mutation. E) They destroy all mutant bacteria.

C) They provide an environment in which preexisting mutants survive.

High concentrations of salt and sugar in foods _____. A) are useful in preserving the food AND tend to force water into a cell. B) have no effect on water availability AND are useful in preserving the food. C) are useful in preserving the food AND tend to force water out of a cell. D) are useful in preserving the food AND force bacteria to divide. E) tend to force water into a cell, causing plasmolysis AND force bacteria to divide.

C) are useful in preserving the food AND tend to force water out of a cell.

Which genetic transfer process requires cell-to-cell contact? A) transformation. B) competency. C) conjugation. D) functional genomics. E) transduction.

C) conjugation.

Pasteurization _____. A) is the use of heat to sterilize food products. B) is a process that uses intense cold to kill microorganisms on foods. C) is the use of heat to reduce numbers of pathogenic/spoilage bacteria in a food item to a safe level. D) is a process that uses short bursts of radiation to kill microorganisms on foods. E) is a process used to preserve only milk and milk products.

C) is the use of heat to reduce numbers of pathogenic/spoilage bacteria in a food item to a safe level.

Which of the following is true of the electron transport system? A) requires a membrane AND requires mitochondria and ribosomes B) uses the nuclear membrane of eukaryotes AND generates a concentration gradient of protons C) requires a membrane AND generates a concentration gradient of protons D) uses the mitochondrial membrane of prokaryotes AND generates a concentration gradient of protons E) requires mitochondria and ribosomes AND generates a concentration gradient of protons

C) requires a membrane AND generates a concentration gradient of protons

Each of the following statements about chemoorganotrophs is true EXCEPT which? A) they may use substrate-level phosphorylation to produce ATP. B) they may use oxidative phosphorylation to produce ATP. C) they may use photophosphorylation to produce ATP. D) they obtain energy by degrading organic compounds. E) they generally rely on the metabolic activities of photosynthetic organisms.

C) they may use photophosphorylation to produce ATP.

Segments of DNA capable of moving from one area in the DNA to another are called what? A) mutations B) oncogenic C) transposons D) conjugative pili E) plasmids

C) transposons

You ask your brother which method of eliminating microbes is the best in general. He tells you that there is no one perfect method and that various factors must be taken into account when considering any antimicrobial approach. These include all of the following EXCEPT _____. A) the type of microbes to be controlled. B) environmental conditions such as temperature. C) whether a potential infection can be easily treated. D) situational considerations (is a method practical for the situation?). E) the number of microbes to be controlled.

C) whether a potential infection can be easily treated.

During which phase of growth are bacteria most susceptible to antibiotics: A. Lag B. Stationary C. Exponential (log) D. Decline E. Death

C. Exponential (log)

The enzymes that combat toxic oxygen containing molecules are: A. Glycolase and superoxide dismutase B. Superoxide dismutase and cytochrome oxidase C. Superoxide dismutase and catalase D. Catalase and cytochrome oxidase E. Cytochrome oxidase and glycolase

C. Superoxide dismutase and catalase

Which is true regarding the three central metabolic pathways? A) They release energy that can be used to synthesize ATP. B) They form intermediates that can be oxidized to generate reducing power. C) They form precursor metabolites. D) All of the answer choices are correct. E) None of the answer choices is correct.

D) All of the answer choices are correct.

Your brother tells you that most likely you ingested Giardia cysts that were in the stream water. He says you should have treated the water before you drank it. Which of the following would NOT have been a possible way for you to do this, as a hiker? A) Boiling the water. B) Using a portable hiker's filter. C) Using commercial water-purifying tablets (iodine). D) Using high pressure processing. E) In fact, none of these would be possible for a hiker.

D) Using high pressure processing.

The most common starting pathway for the breakdown of sugars is which of the following? A) respiration B) fermentation C) Krebs cycle D) glycolysis E) oxidative phosphorylation

D) glycolysis

Enzymes speed up reactions by which of the following? A) raising activation energy B) producing heat C) reducing entropy D) lowering activation energy E) acting as electron carriers

D) lowering activation energy

Bacteria that can absorb light energy and convert it into ATP are commonly called what? A) chemolithotrophs B) chemoorganotrophs C) heterotrophs D) phototrophs E) psycrotrophs

D) phototrophs

Prokaryotic cells divide by a process known as: A. Conjugation B. Mitosis C. Binary fusion D. Binary fission E. Budding

D. Binary fission

Differentiate between disinfectants and antiseptics.

Disinfectants remove microbial growth on the solid surface when anti-septic techniques are used on the skin.

Which of the following describes fermentation? A) uses an inorganic molecule as the final electron acceptor B) uses an organic molecule as the final electron acceptor C) results in the production of a large amount of ATP D) is necessary in some organisms to regenerate electron carriers E) uses an organic molecule as the final electron acceptor AND is necessary in some organisms to regenerate electron carriers

E) uses an organic molecule as the final electron acceptor AND is necessary in some organisms to regenerate electron carriers

Which control methods are best at eliminating endospores?

Extreme heat or chemical treatment. So sterilization methods. (Aldehyde kills endospores)

True or False: Fermentation produces ATP.

False

Discuss why washing your hands is very important although it doesn't kill any microbes directly.

It is the number one way to prevent the spread of disease. This is because the soap and scrubbing under water mechanically removes the microbes (washing them off of you).

How does newly acquired DNA actually change the bacteria's phenotype? What has to occur?

It occurs when the bacteria affects the hosts cell's DNA, therefor affecting the hosts cell's phenotype.

Explain why organisms that utilize fixation (either carbon or nitrogen) are important to all life?

Taking inorganic forms of carbon or nitrogen and converting them to organic forms is usable as energy source for many life forms like us humans.

Who discovered DNA was the transforming principle a) Avery b)McClintock c)Pasteur d)Griffith

a) Avery

What are organisms that use organic molecules as an energy source? a) chemoorganotrophs b) chemolithotrophs c) photoautotrophs d) photolithotrophs

a) chemoorganotrophs

Which of the following requires cell to cell contact? a) transformation b) transduction c)binary fission d)conjugation

d) conjugation

When would ionizing radiation be used? a) wine b) milk c) water d) fruit

d) fruit

The D value is the time of what? a) to kill only pathogens b) to kill 50% of microbes c) to kill 100% of microbes d) to kill 90% of microbes

d) to kill 90% of microbes

What are plasmids?

extra chromosomal DNA

Explain the link between metabolites from catabolic reactions and anabolic reactions.

metabolites form catabolic reactions are used as starting parts to the anabolic reactions.