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171 Cards in this Set

  • Front
  • Back
1. An organism’s interactions with the environment depend on

a. DNA present in the main chromosome.
b. DNA present on extra-chromosomal plasmids.
c. other organisms in the ecosystem.
d. all of the above
d. all of the above
2. Which of the following is an example of a habitat?


a. An organism is able to fix atmospheric nitrogen and share the reduced nitrogen with another species.
b. the benthic region of the ocean
c. An organism eats secondary producers.
d. An organism is classified as picoplankton.
b. the benthic region of the ocean
3. An organism fixes nitrogen for the production of amino acids. This is an example of

a. assimilation.
b. dissimilation.
c. habitat.
d. predation.
a. assimilation.
4. A single-celled eukaryote feeds on cyanobacteria (photoautotrophs). The cyanobacteria are considered

a. decomposers.
b. grazers.
c. predators.
d. primary producers.
d. primary producers.
5. A single-celled eukaryote feeds on cyanobacteria (photoautotrophs). The eukaryote is considered a

a. decomposer.
b. grazer.
c. predator.
d. primary producer.
b. grazer.
6. The major primary producers in terrestrial ecosystems are

a. cyanobacteria.
b. land plants.
c. earthworms.
d. fungi.
b. land plants.
7. Which statement is correct?

a. The ocean is homogeneous and considered a single habitat.
b. All regions of the ocean are capable of supporting phototrophic organisms.
c. Most marine organisms are readily cultured in the lab.
d. The ocean contains many planktonic organisms.
d. The ocean contains many planktonic organisms.
8. An organism that is a strict anaerobe (cannot grow in the presence of oxygen) is most likely to be found in which habitat?

a. euphotic zone of the ocean
b. epilimnion
c. hypolimnion
d. organic horizon
c. hypolimnion
9. One difference between marine and aquatic habitats is that

a. marine habitats usually have a higher salt concentration.
b. only aquatic habitats can support phototrophs.
c. only marine habitats can support predators.
d. there is no difference between marine and aquatic habitats; the words are synonyms.
a. marine habitats usually have a higher salt concentration.
10. An organism classified as a barophile is most likely to be found in which habitat?

a. benthic zone
b. euphotic zone
c. epilimnion
d. aerated horizon
a. benthic zone
11. Which of the following can cause eutrophication?

a. excessive nitrogen inputs
b. algal bloom
c. organic pollutants
d. all of the above
d. all of the above
12. What type of organism is could not be an endolith?

a. heterotroph
b. lithotroph
c. phototroph
d. All of the above are equally likely to be an endolith.
c. phototroph
13. Which organism are you most likely to find living in the rhizosphere?

a. fish
b. nematode
c. bird
d. human
b. nematode
14. To test whether raspberry bushes benefit from the presence of mycorrhizae, which of the following is the best experiment?

a. Compare the growth of mycorrhizae-deficient, lab-grown raspberries to wild raspberry plants.
b. Compare the growth of lab-grown raspberry bushes and blueberry bushes in the presence of mycorrhizae.
c. Compare the growth of lab-grown raspberry bushes in the presence and absence of mycorrhizae.
d. Compare the growth of wild raspberry bushes in one field to the growth of those in a separate field to which fungicide has been added.
c. Compare the growth of lab-grown raspberry bushes in the presence and absence of mycorrhizae.
15. Soil horizons are found in which order from top to bottom?

a. littoral, epilimnion, hypolimnion
b. aerated, organic, eluviated
c. aerated, eluviated, organic
d. organic, aerated, eluviated
d. organic, aerated, eluviated
16. Which of the following molecules is produced mostly in terrestrial and not marine or aquatic ecosystems?

a. lignin
b. nitrogenase
c. DNA
d. oxygen
a. lignin
17. Suppose you run a protein gel on various legume plant parts. Which plant part is most likely to test positive for nitrogenase?

a. flowers
b. leaves
c. roots
d. stems
c. roots
18. High soil levels of nitrate or ammonium ion reduce nodule formation in legumes. This may benefit the plant because

a. rhizobia that populate the nodules are plant pathogens.
b. the plant does not need to supply the rhizobia with chemical energy.
c. the plant does not need to produce amino acids or proteins.
d. none of the above
b. the plant does not need to supply the rhizobia with chemical energy.
19. High soil levels of nitrate or ammonium ion reduce nodule formation in legumes. The plant may accomplish this reduction by

a. decreasing the expression of Nod receptors.
b. increasing the expression of flavonoids.
c. increasing the expression of Nod factors.
d. none of the above
a. decreasing the expression of Nod receptors.
20. Which of the following is a true statement?

a. All plant-fungal interactions are pathogenic.
b. All plant pathogens are fungi.
c. Plants can have bacterial and fungal pathogens and bacterial and fungal mutualists.
d. Plants do not interact with bacteria or fungi in their environment.
c. Plants can have bacterial and fungal pathogens and bacterial and fungal mutualists.
21. What is the purpose of leghemoglobin?

a. It is a bacterial protein that helps transfer reduced nitrogen to the host plant.
b. It is a plant protein that binds oxygen to prevent nitrogenase poisoning.
c. It is a plant protein that delivers N2 to rhizobial bacteria.
d. It is a protein found in the blood of runners to aid oxygen delivery to muscles.
b. It is a plant protein that binds oxygen to prevent nitrogenase poisoning.
22. Fungi can form symbiotic relationships with which of the following organisms?

a. bacteria
b. animals
c. plants
d. a and c only
e. all of the above
e. all of the above
23. Lichens are similar to corals in that

a. both lichens and corals can resist desiccation.
b. both lichens and corals contain a symbiotic partner capable of photosynthesis.
c. both lichens are corals are symbiotic relationships between an algae and a fungus.
d. none of the above
b. both lichens and corals contain a symbiotic partner capable of photosynthesis.
24. Which of the following statements is correct?

a. The rumen is a sterile organ due to the high acidity.
b. Most of the normal rumen microflora are pathogenic to the ruminant.
c. The composition of the ruminant microflora can change depending on the diet.
d. none of the above
c. The composition of the ruminant microflora can change depending on the diet.
25. Some bacteria can have an endosymbiotic relationship with animal cells.

a. true
b. false
a. true
26. Passing contaminated water through a cloth can lower the incidence of cholera because

a. Vibrio cholerae bacteria are exceptionally large and cells do not pass through the cloth.
b. The cloth contains a compound that is toxic to Vibrio cholerae bacteria.
c. The Vibrio cholerae bacteria colonize animals too large to pass through the cloth.
d. Vibrio cholerae are aquatic organisms and the cloth dries them out.
c. The Vibrio cholerae bacteria colonize animals too large to pass through the cloth.
27. All of the E. coli in a person’s digestive tract is an example of

a. an ecosystem.
b. a habitat.
c. a niche.
d. a population.
d. a population.
28. Which of the following is one of van Niel’s postulates of microbial ecology?

a. All organisms possess genomes that encode proteins to enable catabolism.
b. Microbes are found in every environment on Earth.
c. Some carbon compounds cannot be used as a source of energy by any microbes.
d. All organisms depend, directly or indirectly, on the presence of other organisms.
b. Microbes are found in every environment on Earth.
29. Which of the following is an example of dissimilation?

a. Plant roots take up ammonium ion from the soil.
b. Plants release oxygen into the atmosphere during the initial stages of photosynthesis.
c. Animals release carbon dioxide during the oxidative respiration of glucose.
d. Bacteria convert uracil to thymine.
c. Animals release carbon dioxide during the oxidative respiration of glucose.
30. Which trophic level consists solely of microbes?

a. producers
b. grazers
c. consumers
d. decomposers
d. decomposers
31. Which of the following is a true statement?

a. The largest volume of our biosphere is anaerobic.
b. Anaerobic environments support faster rates of growth than aerobic environments.
c. Only endolithic habitats are anaerobic.
d. Anaerobic organisms cannot be autotrophs.
a. The largest volume of our biosphere is anaerobic.
32. Which of the following is an example of symbiosis?

a. A mammal infant obtains breast milk from its mother.
b. Cyanobacteria release oxygen gas that is used by humans during respiration.
c. Colonic bacterial fermentation releases H2 and CO2, which methanogens convert to methane.
d. Many species of fish inhabit coral reefs.
c. Colonic bacterial fermentation releases H2 and CO2, which methanogens convert to methane.
33. A symbiosis in which both partners require the other for survival is known as

a. amensalism
b. commensalism
c. mutualism
d. synergism
c. mutualism
34. Which of the following methods can be used to estimate the rate of marine biomass production?

a. Enumeration of marine microbe with fluorescence microscopy.
b. Metagenomics analysis using PCR amplification of DNA to help uncover unculturable microbes.
c. Quantification of net biomass using chemical assays of protein or other organic matter.
d. Measuring the uptake of a radiolabeled substrate.
d. Measuring the uptake of a radiolabeled substrate.
35. Lignin is converted into humus via

a. assimilation
b. consumption
c. decomposition
d. primary production
c. decomposition
1. Changes in Earth’s atmosphere are influenced by which organisms?

a. animals
b. plants
c. microbes
d. all of the above
a. animals
2. Which of the following elements is a major part (greater than 5% dry cell weight) of most organisms?

a. calcium
b. chlorine
c. iron
d. nitrogen
d. nitrogen
3. Which of the following elements is a micronutrient?

a. carbon
b. hydrogen
c. magnesium
d. oxygen
c. magnesium
4. According to Table 22.2, which of the following reservoirs is the major source or sink of carbon available for living organisms to use?

a. the atmosphere
b. inorganic particles in the ocean
c. Earth’s crust
d. none of the above
b. inorganic particles in the ocean
5. Which of the following is the most reduced form of carbon?

a. carbon dioxide (CO2)
b. formic acid ( HCOOH)
c. methane (CH4)
d. methanol (CH3OH)
c. methane (CH4)
6. The atmosphere contains the most of which element?

a. carbon
b. nitrogen
c. sulfur
d. equal amounts of all three elements.
b. nitrogen
7. Which of the following is an abiotic contributor to global carbon cycling?

a. volcanic outgassing
b. photosynthetic carbon fixation
c. lithotrophy
d. heterotrophic carbon dioxide production
a. volcanic outgassing
8. The atmosphere serves as

a. a sink for carbon.
b. a source of carbon.
c. neither a nor b
d. both a and b
d. both a and b
9. Which of the following is true of carbon cycling?

a. The conversion of CO2 into biomass requires oxygen.
b. The atmosphere is the largest carbon reservoir.
c. Burning fossil fuels increases atmospheric carbon dioxide.
d. Growing forests act as carbon sources.
c. Burning fossil fuels increases atmospheric carbon dioxide.
10. The biochemical oxygen demand (BOD)

a. is usually increased by an increase in organic compounds.
b. is a measure of respiration.
c. is measured to assess environmental water quality.
d. all of the above
d. all of the above
11. In a wastewater treatment plant, microbes are used primarily during

a. primary treatment.
b. secondary treatment.
c. tertiary treatment.
d. all of the above
b. secondary treatment.
12. What happens during primary wastewater treatment?

a. The wastewater is chlorinated to eliminate pathogens.
b. Microbes are added to oxidize organic compounds to carbon dioxide.
c. Insoluble particles are removed by filtration.
d. The wastewater is pumped into drinking water reservoirs.
c. Insoluble particles are removed by filtration.
13. The organisms involved in wastewater treatment include

a. bacterial heterotrophs.
b. methanogens.
c. protists.
d. multicellular nematodes.
e. all of the above
e. all of the above
14. What processes is occurring in this reaction?

NH4+ + NO2− → N2 + 2H20

a. nitrogen fixation
b. ammonification
c. anammox
d. nitrification
c. anammox
15. Nitrogen is often a limiting nutrient for plant growth because

a. it is a small percentage of the atmosphere.
b. plants cannot use the most abundant form of nitrogen (N2).
c. humans are unable to convert N2 into reduced nitrogen.
d. The question is incorrect; nitrogen is not a limiting nutrient.
b. plants cannot use the most abundant form of nitrogen (N2).
16. Which of the following processes produces a form of nitrogen unable to be used by plants for biomass?

a. N2 fixation to ammonium (NH4+)
b. nitrification of ammonia to nitrite (NO2-) and nitrate (NO3-)
c. denitrification of NO2- and NO3- back to N2.
d. none of the above
c. denitrification of NO2- and NO3- back to N2.
17. Cellular nitrogen fixation

a. requires a lot of energy.
b. leads to the oxidation of nitrogen.
c. occurs in the absence of an enzyme.
d. can occur in both prokaryotes and eukaryotes.
a. requires a lot of energy.
18. Nitrate incorporation into biomass is called

a. ammonification.
b. assimilatory nitrate reduction.
c. dissimilatory nitrate reduction.
d. nitrogen fixation.
b. assimilatory nitrate reduction.
19. Which of the following is a greenhouse gas that can warm the atmosphere?

a. carbon dioxide (CO2)
b. methane (CH4)
c. nitrous oxide (N2O)
d. all of the above
d. all of the above
20. Which of the following is a true statement about dissimilatory nitrate reduction?

a. Nitrate acts as an electron donor.
b. It occurs mainly in the presence of oxygen gas (O2).
c. It can lead to the production of N2 or ammonia.
d. It is not an important pathway in the biogeochemical nitrogen cycle.
c. It can lead to the production of N2 or ammonia.
21. The sulfur cycle differs from the nitrogen cycle in that

a. only H2S, and not NH3, is a substrate for photolysis by phototrophs.
b. only nitrogen, and not sulfur, exists in multiple oxidation states.
c. only sulfate, and not nitrate, can be used as an electron acceptor at the end of an electron transport chain.
d. prokaryotes play an important role in nitrogen cycling but not sulfur cycling.
a. only H2S, and not NH3, is a substrate for photolysis by phototrophs.
22. Phosphorous differs from nitrogen and sulfur in that

a. nitrogen and sulfur are found in nucleic acids, but phosphorous is not.
b. phosphorous is a macronutrient, but nitrogen and sulfur are micronutrients.
c. nitrogen and sulfur can be limiting nutrients, but phosphorous is usually not a limiting nutrient.
d. ecosystems contain only oxidized phosphorus, but nitrogen and sulfur exist in many oxidation states.
d. ecosystems contain only oxidized phosphorus, but nitrogen and sulfur exist in many oxidation states.
23. Which of the following statements is true about iron?

a. Most organisms do not require any iron.
b. Iron is a macronutrient for most organisms.
c. Oxidized iron has low solubility in water.
d. Fe2+ can be reduced to Fe3+ during aerobic respiration.
c. Oxidized iron has low solubility in water.
24. If prokaryote contains siderophores, it is likely that

a. the prokaryote uses the siderophore to accumulate environmental sulfur.
b. the prokaryote uses the siderophore to accumulate environmental iron.
c. the prokaryote lives in an environment where phosphorous is the limiting nutrient.
d. the prokaryote lives in the Pacific Ocean but not the Atlantic Ocean.
b. the prokaryote uses the siderophore to accumulate environmental iron.
25. Which of the following can be a limiting nutrient in an ecosystem?

a. iron
b. nitrogen
c. phosphorous
d. any of the above
d. any of the above
26. Microbes metabolize metals in ways that are

a. beneficial to human health.
b. detrimental to human health.
c. either beneficial or detrimental depending on the element.
d. neither beneficial nor detrimental as microbes do not metabolize metals.
c. either beneficial or detrimental depending on the element.
27. Mars may be the most likely planet (besides Earth) to have harbored life because

a. it has an oxygen gas containing atmosphere similar to Earth’s atmosphere.
b. there are indications that it may have had liquid water.
c. daytime temperature averages about 30°C, similar to what can be found in some regions of Earth.
d. all of the above
b. there are indications that it may have had liquid water.
28. It is possible that life may exist on

a. Mars.
b. some of Jupiter’s moons.
c. planets in other solar systems.
d. all of the above
d. all of the above
31. Dissimilatory nitrate reduction can lead directly to the production of

a. amino acids and nucleotides.
b. NO2 and NO3.
c. N2 and NH3.
d. none of the above.
c. N2 and NH3.
32. Which of the following reduces atmospheric carbon dioxide levels?

a. microbial carbon dioxide fixation
b. fungal decomposition of detritus
c. oxidation of petroleum
d. burning of forests
a. microbial carbon dioxide fixation
33. Which of the following is the most oxidized form of nitrogen?

a. NO
b. NH3
c. NO3-
d. NO2-
c. NO3-
34. In aerobic ecosystems

a. only bacteria and archaea produce biomass.
b. there is usually little light.
c. the rate of heterotrophy exceeds the rate of photosynthesis.
d. there are relatively high levels of biomass production.
d. there are relatively high levels of biomass production.
35. BOD is measured by

a. analyzing decreases in dissolved oxygen in water samples.
b. analyzing increases in dissolved organic material in water samples.
c. analyzing decreases in dissolved organic material in water samples.
d. using a microscope to enumerate the number of heterotrophic bacteria present in a water sample
a. analyzing decreases in dissolved oxygen in water samples.
1. Which of the following locations is least likely to harbor commensal microbes?

a. the skin
b. the blood
c. the mouth
d. the vagina
b. the blood
2. Microbes that colonize the skin need to be resistant to which conditions?

a. low salt and high pH
b. low salt and low pH
c. high salt and low pH
d. high salt and high pH
c. high salt and low pH
3. Which of the following bacteria is a major cause of tooth decay?

a. Streptococcus mutans
b. Propionibacterium acnes
c. Escherichia coli
d. Dentus caries
a. Streptococcus mutans
4. Bacteremia is

a. the genus of bacteria that normally colonize the skin .
b. an antibiotic produced by fungi that is used clinically as a topical microbicide.
c. an infection of the bloodstream.
d. none of the above
c. an infection of the bloodstream.
5. The environment inside the intestine is largely

a. aerobic .
b. anaerobic.
c. aerobic in the duodenum and jejunum but anaerobic in the ileum and colon.
d. none of the above
b. anaerobic.
6. Which of the following is true of the normal intestinal microbiota?

a. The microbes that are present will not harm the host if they colonize a different tissue.
b. There are up to two dozen different species present.
c. The normal microbiota contains only bacterial species.
d. They can help aid digestion and absorption of nutrients.
d. They can help aid digestion and absorption of nutrients.
7. The balance of the normal intestinal microbiota can be upset by

a. emotional stress.
b. antibiotic therapy.
c. dietary changes.
d. all of the above
d. all of the above
8. A doctor prescribing antibiotics to a female patient may recommend she increase her consumption of yogurt. The reasoning is that

a. the yogurt will also help fight the bacterial infection.
b. probiotic bacteria in the yogurt may prevent a yeast infection.
c. the antibiotic may leach calcium from the body and yogurt is a good calcium source.
d. none of the above
b. probiotic bacteria in the yogurt may prevent a yeast infection.
9. Commensal species may interfere with colonization of pathogens by which mechanism?

a. competition for attachment receptors on host cells
b. competition for food sources
c. through the synthesis of antimicrobial compounds
d. all of the above
d. all of the above
10. Gnotobiotic animals

a. are used in research.
b. can normally be found in as a small percentage of wild populations.
c. have enhanced immune functions.
d. all of the above
a. are used in research.
11. Which of the following is true of opportunistic pathogens?

a. They are always untreatable, being antibiotic resistant.
b. They usually infect people with normal, functioning immune systems.
c. They may arise from normal microbiota.
d. all of the above
c. They may arise from normal microbiota.
12. Which of the following helps prevent microbial growth on mucosal membranes?

a. the high moisture content
b. the presence of lysozyme
c. the presence of keratin
d. all of the above
b. the presence of lysozyme
13. Which of the following is a physical barrier to microbial infection?

a. acidic pH
b. superoxide radicals
c. tightly linked epithelial cells
d. antimicrobial peptides
c. tightly linked epithelial cells
14. Which of the following compounds are produced by bacteria?

a. cytokines
b. defensins
c. immunomodulins
d. keratin
c. immunomodulins
15. Innate immunity is also called

a. adaptive immunity.
b. antibody-mediated immunity.
c. antigen-mediated immunity.
d. nonadaptive immunity.
d. nonadaptive immunity.
16. Invading microbes usually need to overcome host defenses in which following order?

a. physical barriers, innate immunity, adaptive immunity
b. physical barriers, adaptive immunity, innate immunity
c. adaptive immunity, innate immunity, physical barriers
d. adaptive immunity, physical barriers, innate immunity
a. physical barriers, innate immunity, adaptive immunity
17. What do all white blood cells have in common?

a. They are all antigen-presenting cells (APCs).
b. They are all capable of phagocytosis of foreign particles.
c. They all posses hemoglobin.
d. They all differentiate from stem cells found in bone marrow.
d. They all differentiate from stem cells found in bone marrow.
18. Which of the following is a secondary lymphoid organ?

a. bone marrow
b. spleen
c. thymus
d. all of the above
b. spleen
19. Extravasation of immune cells depends on

a. increased leakiness of endothelial cells.
b. antibody production by B cells.
c. down-regulation of selectin proteins on endothelial cells.
d. all of the above
a. increased leakiness of endothelial cells.
20. Chronic inflammation can be caused by

a. microbes that resist host defenses.
b. the continued presence of a non-living irritating particle.
c. autoimmune reactions.
d. all of the above
d. all of the above
21. A granuloma is

a. a cancer caused by the uncontrolled proliferation of granulocytes.
b. a bacterial protein that prevents phagocytosis of the bacteria.
c. a thick lesion formed around a site of infection.
d. none of the above
c. a thick lesion formed around a site of infection.
22. Which cells are capable of phagocytosis?

a. B cells
b. macrophages
c. neutrophils
d. a and b
e. b and c
f. a, b, and c
e. b and c
23. Which receptors recognize bacterial proteins?

a. CD-47 receptors
b. Fc-receptors
c. Toll-like receptors
d. all of the above
c. Toll-like receptors
24. If a human microbial pathogen developed the ability to express CD-47 on its cell surface, a possible outcome could be that

a. the pathogen would not be able to breach epithelial cell barriers.
b. the pathogen would not be engulfed by macrophages.
c. the pathogen would be unable to produce immunomodulins.
d. the pathogen would lose virulence and cease to be pathogenic.
b. the pathogen would not be engulfed by macrophages.
25. Type 1 interferons

a. help protect cells from viral infection.
b. are produced in response to extracellular pathogens.
c. are not species specific (e.g., rabbit interferon will work in mice).
d. reduce cellular levels of ds RNA endonucleases.
a. help protect cells from viral infection.
26. If an organism was unable to produce natural killer cells, then it

a. would be unable to produce any interferons.
b. might be more susceptible to anemia, due to a loss of red blood cells.
c. might be less susceptible to viral infections.
d. might be more susceptible to cancer.
d. might be more susceptible to cancer.
27. Which complement cascade pathway depends on the production of antibodies?

a. the alternative pathway
b. the classical pathway
c. the lectin pathway
d. all of the above
b. the classical pathway
28. Which of the following cells is most likely to be killed via the alternative complement pathway?

a. a virally infected host cell
b. a gram-positive bacterium
c. a gram-negative bacterium
d. all of the above
c. a gram-negative bacterium
29. Pyrogens indirectly cause the hypothalamus to

a. increase the temperature set point.
b. decrease the temperature set point.
c. keep the temperature set point the same.
a. increase the temperature set point.
31. Which of the following happens during inflammation?

a. The capillaries become more leaky.
b. Prostaglandins deaden nerve endings, alleviating pain.
c. Neutrophils release histamine.
d. all of the above
a. The capillaries become more leaky.
32. Which of the following is true of neutrophil endothelial cell interactions?

a. Endothelial cells always express selectins that can bind to a slow neutrophils
b. Neutrophils always express integrins on their surface that can bind to adhesion molecules on endothelial cells.
c. Expression of endothelial selectins and neutrophil integrins is regulated.
d. Cytokines on neutrophils interact with bradykinin on endothelial cells, causing neutrophils to roll along the endothelium.
c. Expression of endothelial selectins and neutrophil integrins is regulated.
33. Which of the following is true of macrophages?

a. They are the cell most likely to first encounter an invading pathogen.
b. They participate in the innate immune response but not in the adaptive immune response.
c. They produce antibodies in response to antigens presented by antigen-presenting cells.
d. They are unable to perform phagocytosis.
a. They are the cell most likely to first encounter an invading pathogen.
34. The vesicle that results from engulfment of a bacterium by a cell of the innate immune system is called a

a. granuloma.
b. lysosome.
c. phagosome.
d. histocompatibility complex.
c. phagosome.
35. Which human ecosystem carries the largest bioburden?

a. genitourinary
b. intestine
c. mouth
d. skin
b. intestine
1. Which of the following is an example of an ectoparasite?

a. HIV, human immunodeficiency virus
b. herpes simplex virus
c. Pediculus humanus capitis (head lice)
d. septicemic (in the blood stream) N. meningitides
c. Pediculus humanus capitis (head lice)
2. A certain pathogen is not easily acquired by individuals, but has an 85% mortality rate among those unfortunate enough to acquire it. This pathogen is

a. highly infectious and highly virulent.
b. highly infectious and minimally virulent.
c. minimally infectious and minimally virulent.
d. minimally infectious and highly virulent.
d. minimally infectious and highly virulent.
3. Pathogen A has an LD50 of 10,000 organisms and pathogen B has an LD50 of 200,000 organisms. Which pathogen is more virulent?

a. pathogen A
b. pathogen B
a. pathogen A
4. Humans can contract pathogens via

a. contact with other humans.
b. contact with animal vectors.
c. contact with fomites.
d. all of the above.
d. all of the above.
5. A gene coding for which of the following proteins is likely to be found in a genomic island of a pathogenic bacterial strain and not found in a non-pathogenic strain?

a. tRNA amino acyl synthase protein
b. host cell attachment protein
c. RNA polymerase protein
d. glucose transporter protein
b. host cell attachment protein
6. Which of the following is evidence that a pathogenicity island was initially acquired by horizontal transfer?

a. It is passed on to daughter bacteria during cell division.
b. It contains genes for core, fundamental biological processes such as transcription.
c. It has a GC percentage different from the rest of the genome.
d. all of the above
c. It has a GC percentage different from the rest of the genome.
7. Blocking mannose on host cells will likely prevent attachment by bacteria bearing

a. Type I pili.
b. Type III pili.
c. Type IV pili.
d. all of the above
a. Type I pili.
8. In gram-negative organisms such as E. coli, host-attachment pili are embedded in

a. the inner membrane.
b. the layer of peptidoglycan.
c. the outer membrane.
d. all of the above.
c. the outer membrane.
9. Which type of pilus is dynamic (can lengthen and shorten) and can cause motility?

a. Type I pili
b. Type III pili
c. Type IV pili
d. all of the above
c. Type IV pili
10. Microbial exotoxins posses which of the following activities?

a. inhibition of eukaryotic ribosomes
b. disruption of host-cell membranes
c. disruption of host-cell second messenger signaling pathways
d. all of the above
d. all of the above
11. E. coli-labile toxin and cholera toxin

a. ADP-ribosylate cAMP, which as a result cannot activate protein kinase A.
b. ADP-ribosylate a G-protein, which as a result constantly activates adenylate cyclase.
c. ADP-ribosylate protein kinase A, inhibiting its function.
d. secrete proteases that cleave host-cell proteins.
b. ADP-ribosylate a G-protein, which as a result constantly activates adenylate cyclase.
12. Fresh cell-culture media and media that a bacterial strain was grown in are injected separately into different mice. Only the mice that received the bacterial-exposed media become ill, but this effect is negated by first treating the media with a proteinase. This finding suggests that

a. the bacteria do not secrete any exotoxins.
b. the proteinase is harmful for the mice.
c. the bacteria secrete a protein exotoxin.
d. the bacteria secrete a non-protein exotoxin.
c. the bacteria secrete a protein exotoxin.
13. Which of the following toxins is produced by all Gram-negative bacteria?

a. anthrax toxin
b. shiga toxin
c. diptheria toxin
d. endotoxin
d. endotoxin
14. From the bacteria’s standpoint, an advantage of a type III secretion system for toxin delivery is that

a. the toxin is not diluted in the environment.
b. it does not require the bacteria to produce any specialized delivery proteins.
c. the toxin has an easier time binding to host-cell membrane receptors for endocytosis into the cytoplasm.
d. toxins delivered this way are more virulent than exotoxins.
a. the toxin is not diluted in the environment.
15. Which type of secretion system resembles conjugation machinery?

a. type II secretion
b. type III secretion
c. type IV secretion
d. none of the above
c. type IV secretion
16. Suppose you delete a suspected virulence gene in a pathogenic organism. If the gene product did indeed enhance virulence, your modified organism will have

a. a slower growth rate in culture media compared to the unmodified, gene-containing organism.
b. a higher LD50 than the unmodified, gene-containing organism.
c. increased infectivity compared to the unmodified, gene-containing organism.
d. a greater range of host organisms it can infect.
b. a higher LD50 than the unmodified, gene-containing organism.
17. In the cat lacZ in vivo expression technology assay, which finds promoters that only allow gene expression in a host, positive plasmids are ones that are

a. resistant to chloramphenicol in a host and express B-gal on artificial media.
b. resistant to chloramphenicol in a host and lack B-gal on artificial media.
c. sensitive to chloramphenicol in a host and express B-gal on artificial media.
d. sensitive to chloramphenicol in a host and lack B-gal on artificial media.
b. resistant to chloramphenicol in a host and lack B-gal on artificial media.
18. Shigella and Listeria move inside host eukaryotic cells by

a. propelling themselves with their flagella.
b. causing host-derived actin to polymerize behind them.
c. extending pseudopods within the host cell.
d. moving along host microtubule tracks.
b. causing host-derived actin to polymerize behind them.
19. A human obligate intracellular parasite can grow in phagolysosomes. From this information we can assume that this organism can grow in

a. acidic conditions.
b. alkaline conditions.
c. temperatures greater than 42°C.
d. environments extremely high in sodium chloride.
a. acidic conditions.
20. To “pull down” soluble antibodies, sepharose beads coated with a protein that recognizes all antibodies can be added to an antibody solution and the mixture centrifuged. The protein used to coat the sepharose beads is

a. protein A from Staphylococcus aureus.
b. C3b complement factor from Homo sapiens.
c. diptheria toxin from Corynebacterium diphtheriae.
d. cyclic adenosine monophosphate (cAMP).
a. protein A from Staphylococcus aureus.
21. Extracellular pathogens can attempt to avoid immune detection by

a. inhibiting phagosome-lysosome fusion.
b. growing within a phagolysosome.
c. altering their cell-surface proteins.
d. all of the above
c. altering their cell-surface proteins.
22. Bacteria can determine they are in a host cell by measuring

a. environmental magnesium concentrations.
b. pH.
c. environmental iron concentrations.
d. all of the above
d. all of the above
23. Quorum sensing, the ability of bacteria to assess their numbers,

a. can only occur when bacteria are in direct contact with each other.
b. can only occur after virulence factors have been secreted.
c. may be a target for antibiotics that inhibit quorum sensing.
d. all of the above
c. may be a target for antibiotics that inhibit quorum sensing.
24. The symptoms of colds (e.g., runny nose) and flu (e.g., muscle aches) are due to

a. the systemic release of viral toxins.
b. host factors released in response to viral infection.
b. host factors released in response to viral infection.
25. A person can contract the flu each year because

a. people do not make memory B cells against viral antigens.
b. the antigens on the virus shift and each year different strains emerge.
c. people cannot contract the flu each year; you can only get influenza once and subsequent illnesses called the “flu” are actually just really bad colds.
d. once a year, on a person’s birthday, all memory B cells are destroyed so there is room in the blood for new ones.
b. the antigens on the virus shift and each year different strains emerge.
26. Which of the following is not an HIV-encoded protein?

a. CD4
b. gp120
c. negative factor (NEF)
d. Tat protein
a. CD4
28. Cholera is usually transmitted by

a. inhaling Vibrio cholerae bacteria present as aerosolized particles in the atmosphere.
b. sharing needles or having sex with a person suffering from cholera.
c. ingesting food or water contaminated with Vibrio cholera from human feces.
d. being bitten by the insect vector that transmits cholera among different animal hosts.
c. ingesting food or water contaminated with Vibrio cholera from human feces.
29. What is the correct sequence of events in cholera toxin production of diarrhea?

a. Increased activity of adenylate cyclase, increased activity of CFTR, increased activity of protein kinase A.
b. Increased activity of CFTR, increased activity of protein kinase A, increased activity of adenylate cyclase.
c. Increased activity of protein kinase A, increased activity of adenylate cyclase, increased activity of CFTR.
d. Increased activity of adenylate cyclase, increased activity of protein kinase A, increased activity of CFTR.
d. Increased activity of adenylate cyclase, increased activity of protein kinase A, increased activity of CFTR.
30. Which of the following is true of Type III secretion system?

a. The effector proteins pass through the needles in an unfolded state.
b. No energy is required for the effector proteins to pass through the secretion system.
c. Only a single type of effector protein is delivered into the host cell cytoplasm.
d. all of the above
a. The effector proteins pass through the needles in an unfolded state.
31. The pathway that pathogens take from one organism to another is called

a. horizontal transmission.
b. vertical transmission.
c. the infection cycle.
d. the latent state.
c. the infection cycle.
32. Which of the following is an example of vertical transmission?

a. Children get ill from food prepared by their mother.
b. Insects pass the yellow fever virus to their offspring in their eggs.
c. Insects pass the yellow fever virus to humans upon biting them.
d. A child catches a cold because her mother sneezed and coughed on her.
b. Insects pass the yellow fever virus to their offspring in their eggs.
33. Horizontal transmission of pathogenicity genes may occur via

a. conjugation
b. transduction
c. either conjugation or transduction
d. neither conjugation nor transduction
c. either conjugation or transduction
34. Biofilms

a. are a homogeneous population of bacteria.
b. exhibit increased antibiotic sensitivity.
c. adhere less tightly to surfaces than individual bacteria.
d. may cause disease by colonizing medical implants.
d. may cause disease by colonizing medical implants.
35. Helicobacter pylori, a causative agent of gastric ulcers, contains a gene that encodes the protein urease. The urease enzyme

a. propels H. pylori toward the stomach lining.
b. raises the pH of the stomach.
c. digests through the stomach’s mucus layer.
d. attaches to host cell proteins to facilitate bacterial attachment.
b. raises the pH of the stomach.
1. Sequelae occur

a. after an infection due to antibody cross-reactivity.
b. during a primary infection due to microbial toxin release.
c. during antibiotic treatment as a result of allergies to specific antibiotics.
d. none of the above
a. after an infection due to antibody cross-reactivity.
2. Identification of the microbe infecting a patient is useful because

a. it may allow physicians and epidemiologists to track the source of the infection.
b. antibiotic resistance of the microbe can be checked, allowing appropriate prescriptions to be written.
c. doctors and patients can be alerted to strain-specific complications.
d. all of the above
d. all of the above
3. Differential media help discriminate among organisms based on their

a. morphology.
b. biochemistry.
c. ability to retain the Gram stain.
d. infectivity.
b. biochemistry.
4. A pathogen is identified as a Gram-negative rod that can grow on blood agar. This organism may be

a. Neisseria meningitides.
b. Haemophilus influenzae.
c. Escherichia coli.
d. Streptococcus pneumonia.
c. Escherichia coli.
5. Which of the following helps aid the identification of a pathogen?

a. differential staining
b. growth on differential media
c. morphology
d. all of the above
d. all of the above
6. Which media type allows growth of the most species?

a. blood agar
b. chocolate agar
c. Hektoen agar
d. The media are equivalent, so all can support the same number of species.
b. chocolate agar
7. Which of the following is not true of the Enterobacteriaceae?

a. They contain cytochrome C.
b. They are gram-negative.
c. They are rod shaped.
d. Some members may be pathogens.
a. They contain cytochrome C.
8. The identification of a microbe using an algorithm means that

a. the organism’s transcriptome is analyzed on a gene chip.
b. the identification process can happen within minutes.
c. a series of yes/no answers leads to the next test.
d. a coagulase test will be performed on the microbe under question.
Feedback/Reference: An algorithm is series of yes or no questions about the clinical specimen in the form of biochemical or serological tests. A coagulase test may or may not be performed, depending on the answers to previous tests in the algorithm.
c. a series of yes/no answers leads to the next test.
9. Which organisms rupture red blood cell membranes?

a. α-hemolytic
b. β-hemolytic
c. non-hemolytic
d. none of the above
b. β-hemolytic
10. An algorithm of biochemical tests can be used to identify

a. a bacterial pathogen.
b. a viral pathogen.
c. an emerging pathogen.
d. all of the above
a. a bacterial pathogen.
11. Which of the following methods is a molecular genetic means of pathogen identification?

a. analytical profile index (API) strips
b. analysis of growth on differential agar
c. immunologic screening of cell wall peptidoglycans
d. polymerase chain reaction
d. polymerase chain reaction
12. The acid-fast stain is used to identify

a. gram-negative organisms.
b. gram-positive organisms.
c. mycobacteria.
d. fungi.
c. mycobacteria.
13. Which of the following techniques for determining the strain of a microbe relies on restriction enzymes?

a. acid-fast staining
b. enzyme-linked immunosorbent assay (ELISA)
c. polymerase chain reaction (PCR)
d. restriction fragment length polymorphism (RFLP)
d. restriction fragment length polymorphism (RFLP)
14. The enzyme-linked immunosorbent assay (ELISA) can capture and detect either antigens or antibodies depending on the setup of the assay. Which one will allow detection of an infection at an earlier stage?

a. antibody-capture ELISA
b. antigen-capture ELISA
c. The two types of ELISAs are equally good at detecting very early infections.
b. antigen-capture ELISA
15. A single microbial species can often have different strains or serotypes. Which method can discriminate among them?

a. staining with fluorescent antibodies
b. staining with the Gram stain
c. restriction fragment length polymorphisms
d. a and c
e. all of the above
d. a and c
16. Which method is not used to detect viral pathogens?

a. biochemical assays
b. immunological methods
c. molecular techniques
d. all of the above
a. biochemical assays
17. Bacterial species can be identified using

a. biochemical analyses.
b. immunological methods.
c. molecular techniques.
d. all of the above
d. all of the above
18. Specimens were obtained from four body areas and plated separately on chocolate agar. Colonies appeared on all four plates. Which one indicates a problem?

a. throat
b. rectum
c. blood
d. vagina
c. blood
19. Which of the following media is non-selective?

a. blood agar
b. CNA agar
c. Hektoen agar
d. MacConkey agar
a. blood agar
20. A physician orders a mid-stream clean catch for analysis. What will be analyzed?

a. blood
b. fecal material
c. sputum
d. urine
d. urine
21. A needle aspiration is taken from an abscess. It is possible the pathogenic organism is an anaerobe. Care must be taken to avoid exposing the specimen to

a. acetic acid.
b. oxygen.
c. carbon dioxide.
d. water.
b. oxygen.
22. Pathogens in which biosafety level can be transmitted via respiratory secretions?

a. category I
b. category II
c. category III
d. category IV
e. categories I and II
f. categories III and IV
f. categories III and IV
23. Ebola virus is a

a. category I agent.
b. category II agent.
c. category III agent.
d. category IV agent.
d. category IV agent.
24. A certain bacterium has as its reservoir a rodent only found in the Southwest United States. Each year a few human cases of the disease caused by this bacterium are reported in Arizona and New Mexico. This disease can be described as

a. epidemic.
b. endemic.
c. pandemic.
d. virulent.
b. endemic.
25. There are certain infectious diseases that physicians must report to the Center for Disease Control.

a. true
b. false
a. true
26. How was the causative agent of Whipple’s disease discovered?

a. The organism was isolated from patients, cultured in the lab, and produced Whipple’s disease in mice inoculated with the organism.
b. PCR fragments of bacterial 16S rRNA genes from Whipple’s disease patients and healthy controls indicated no differences.
c. PCR fragments of bacterial 16S rRNA genes from Whipple’s disease patients and healthy controls indicated a fragment the same in all patients but missing from controls.
d. PCR fragments of bacterial 16S rRNA genes from Whipple’s disease patients and healthy controls indicated that each patient had a unique PCR product not found in healthy controls or other patients.
c. PCR fragments of bacterial 16S rRNA genes from Whipple’s disease patients and healthy controls indicated a fragment the same in all patients but missing from controls.
27. Which technique can detect Mycobacterium tuberculosis at the earliest stage of infection?

a. diagnostic acid-fast staining of sputum
b. polymerase chain reaction
c. chest X-rays
d. all of the above
b. polymerase chain reaction
28. An effective bioweapon should

a. have a low infectious dose.
b. be easily transmitted between people.
c. encounter resistance in only a few people.
d. all of the above
d. all of the above
29. For which disease was the causative agent identified within a few months after the first patient cases were reported?

a. AIDS
b. Lyme disease
c. SARS
d. all of the above
c. SARS
30. Which of the following may contribute to the spread of emerging diseases?

a. enhanced human mobility
b. blood transfusions
c. food-processing practices
d. all of the above
d. all of the above
31. The API 20E strip assay is used to identify species within the order

a. Bacillales
b. Clostridiales
c. Enterobacteriaceae
d. Rickettsia
c. Enterobacteriaceae
32. Most viral diseases are diagnosed using

a. stained clinical specimens.
b. biochemical algorithms.
c. serological methods.
d. none of the above.
c. serological methods.
33. Serological methods can diagnose

a. only bacterial diseases.
b. only viral diseases.
c. both bacterial and viral diseases.
d. neither bacterial nor viral diseases.
c. both bacterial and viral diseases.
34. A patient is fatigued with a persistent cough. Her physician wants to test for Mycobacterium tuberculosis. What specimen is the physician most likely to ask for?

a. blood
b. lumbar puncture for cerebrospinal fluid
c. sputum
d. throat swab
c. sputum
35. In epidemiology, patient zero is

a. the last person to have contracted the disease. After this person there are no more (zero) patients.
b. the first known case of a disease.
c. the designation given to everyone who is quarantined and needs to have zero associations with non-infected patients.
d. the first person to have died from an emerging pathogen.
b. the first known case of a disease.