exam 3 questions

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exam 3 questions
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  1. 1. Which one of the following microbial guilds is not part of the microbial community that develops in the Winogradsky’s column?
    A. Sulfate reducers B. Oxygenic photosynthestic microbesD. Nitrifiers E. All of the above develop in the column
    c
  2. 2. As an employee of an environmental consulting company you have been asked to isolate oil degrading bacteria that could be used for the cleaning up of a contaminated beach following an oil spill. You decide to set up an enrichment culture for these bacteria. Which of the following ingredients would you include in your enrichment culture?
    A sample of the oil that was spilled on the beach B Ammonium as a nitrogen source C Phosphate as a phosphorous source D sample of the contaminated beach sand E All of the above
    e
  3. Which one of the following methods is a culture-dependent method in microbial ecology?
    A Denatured gradient gel electrophoresis (DGGE) B In-situ reverse transcriptase (ISRT) C Stable isotope fractionation D The most probable number method (MPN E Microautoradiography
    D
  4. 4. “Think small” in microbial ecology means that:
    A.When considering microbial life in the environment one should realize that conditions that arecritical to life may change within very small distancesB.Microbes are very small C. Small differences matters a lot D. Do not think too much because microbial life in the environment is very simple E. None of the above
    A
  5. A Biofilm is
    A. A microbial community that forms at the interface between solid and aqueous phases B. A genetically programmed process that lead to the formation of a uniquely structured microbial community C A major economic concern because of serious harms to certain industries D. An example of how quorum sensing regulates gene expression E. All of the above
    e
  6. In the marine water column the ratio between Bacteria and Archaea is about:
    A Four bacterial cells for every archeal cell
    B Three bacterial cells for every archeal cell
    C About the same (one bacterial cell for every archeal cell) D Four arecheal cells for every bacterial cell E There are no Archaea in the marine water column
    B
  7. Which of the following processes is a part of the carbon cycle:
    A Photosynthesis B Sulfate reduction C Nitrogen fixation D Anammox E Pyrite oxidation
    A
  8. The rumen is an organ where:
    A Plant material is being converted to fatty acids, vitamins, and amino acids, which is the basis for the nutrition of the ruminating animal B Aerobic conditions dominate C Very few microbes can live and fungi are the dominating microbes The Ddominating microbial process in aerobic respiration E All of the above
    A
  9. Mycorrhizae fungi benefs their partner plants because they:
    A Increase the sorption of nutrient and water from the soil B Solubilize essential nutrients such as phosphate C Protect the plant from invasion by pathogens D Increase plant diversity
    E. All of the above
    e
  10. Which of the following organisms is most likely to be implicated in dental caries?
    A. Staphylococcus aureusB. Staphylococcus epidermidisD. Escherichia coli
    c
  11. HSV-2 (Herpes simplex virus) is a
    A. foodborne virus B. virus common in rodentsD. causesflu-likesymptoms
    c
  12. Which exotoxin binds to the presynaptic terminal membrane at the neuromuscular junction, blocking the release of acetylcholine?
    A. Diphtheria toxin B. Tetanus toxinD. Cholera toxin
    c
  13. The enterotoxins of Escherichia and Salmonella have modes of action similar to that of the cholera toxin.
    A TRUE B FALSE
    A
  14. . I am a cute and friendly creature, but I can also carry some nasty bacteria. Who am I and what kind of infectious microorganism I may carry?
    Armadillo and Mycobacterium
  15. The most common cause of urinary tract infections in hospitals is
    A. Escherichia coli B. Staphylococcus aureus C. Pseudomonas aeruginosa D. Candida albicans
    a
  16. . I am a very friendly and loveable creature – yet people are afraid of me for some reason. Please, tell me who I am, why I shoudl be afraid of and which body took action against me in the US.
    A. American marten, spread cholera, FDA ban B. European polecat, spreads prions, import banned by USDA and FDAC. C. Civet, may carry SARS, import banned by CDC
    c
  17. 17. Where is Bacillus anthracis typically found?
    A. In cattle reservoirsC. In rodent reservoirs D. In human reservoirs
    b
  18. Infections with Clostridium tetani cannot be controlled since the organism is a component of the soil.
    A true B False
    b
  19. The Bacillus anthracis toxin is a two-component system which is active in a form of PA + LF or PA + EF. The currently developed anti-anthrax vaccines are actually targeting:
    A. PA B. LF C. EF D. PA+LF+EF
    a
  20. . Which statement is true?
    A. Coagulation leads to flocculation B. Flocculation leads to coagulation C. Coagulation occurs after filtration D. Flocculation occurs after filtration
    a
  21. The cholera organism is a (select correct answer):
    A. Gram-positive rod B. Gram-negative curved rodC. Gram-positive coccus D. Gram-negative coccus
    B
  22. . The causative agent of typhoid fever is:
    A. Salmonella typhi B. Salmonella typhimurium C. Shigella flexneri D. Escherichia coli
    a
  23. Select the correct requirements for probiotics (one answer):
    A. Probiotics must be derived from humans B. Probiotics must belong to the group of lactic acid bacteria C. Probiotics must deliver a measurable physiological benefit D. Survival of gastrointestinal tract transit and impact on normal flora are absolutely required
    c
  24. Name the microorganism) is largely responsible for the synthesis of a floating cellulose network during the Kombucha tea fermentation. A. Aspergillus sp.
    A. Aspergillus sp. B. Lactobacillus casei C. Acetobacter xylinnum D. Lactobacillus lactis
    c
  25. Food poisoning can be cause by ingestion of Clostridium botulinum.
    A true B False
    a
  26. Bacteriophages are successfully used for combating certain infectious diseases in humans.
    A true B false
    a
  27. What are the two major processes that determine the rate of organic matter production? The rate of which one of them has to be higher for the accumulation of organic matter?
    The two processes are photsynthesis (P), which leads to the production of organic matter, andrespiration ®, which leads to the degradation of organic matter. When P>R organic matteraccumulate
  28. What are the two major characteristics that describe microbial communities? Please provide a brief definition of each of these characteristics
    The major characteristics are community structure and community function.Community structure describes the various taxa that comprise the communitiesand their relative abundance in the environment. Community function describesthe activities and their rates as performed by the community in the environment
  29. What is the scientific principle that makes stable isotopes fractionation such an important tool in microbial ecology? What is the information that is obtained by this method?
    29. What is the major source of energy in the deep sea hydrothermal vent environment and how is this energy being used to support the diverse living community in the vent environment?Microbial activities favor the utilization of light stable isotopes because less energy is required to eithersynthesize or degrade a chemical bond between lighter than heavier isotopes of the same chemicalelement. Using this approach one can determine if a specific substance in the environment is theproductof mirobial transformations
  30. 29. What is the major source of energy in the deep sea hydrothermal vent environment and how is this energy being used to support the diverse living community in the vent environment?
    The major source of energy are reduced chemical elements, such as sulfur and iron, in the hydrothermalvent fluids and microorganisms that obtain energy by oxidizing these reduced chemicals are the primaryproducers which provide the basis of the vent food chain.
  31. In your own words, describe molecular mechanism of action of the cholera toxin (don’t forget to mention the type of toxin) and the consequences for the human organism. What is the major way of treatment cholera?
    Cholera exotoxin (choleragen), produced byVibrio cho/erae.This exotoxin catalyzes the ADP-ribosylation ofahost cell protein calledGsthat turns the synthesis ofametabolic regulatormoleculecalled cyclic AMP (cAMP) on and off.Inthis case, synthesis stays turned on. High levels ofcAMPblock intestinal epithelial cells from taking in sodium from the lumen ofthe intestines and stimulatesthem to secrete large quantities ofchloride.Waterandotherelectrolytesosmotically follow.Thiscausesloss offluids, diarrhea,andsevere dehydration. The main treatment for choleraisto drinkplenty of fluids to rehydrate.
  32. This question was inspired by the in-class discussion (thanks to one of the students). Bacteriophages are rather selective in their targets. Please, elaborate on following. Can they be used to control non-desired microorganisms in foods? Will that create any danger for human health? Do you see them being approved by FDA for food preservation? Since bacteria aver very smart and know how to build resistance against various stresses, what needs to be done to prevent resistance to bacteriophages?
    The bacteriophages can be used as food preservatives -in fact, they were approved by FDA. They create no threat to human health since they are active only against bacteria. However, they may induce lysis of the pathogen with additional release oftoxin(s). To avoid bacterial resistance, cocktails of different bacteriophages should be used.
  33. Secondary treatment of the waste water. Describe the goal of this treatment. What is so special in the design of the trickling filter? Now that you have got all this sludge on your hands – what can you do with it?
    Organic carbon is converted to C02 and microbial biomassTrickling filter -a bed ofrocks (10-15 em in diameter) at a 2 m depth. The thick biofilm thatforms on the rocks oxidizes organic matterActivated sludge -5 -10hoursretention; flocks consisting of bacteria(Zoog/oea ramigera)embeddedinEPS (slime) and eukaryotic microbesThe sludge may be digested anaerobically or dried and used as a fertilizer
  34. s question was inspired by the in-class discussion (thanks to one of the students). Bacteriophages are rather selective in their targets. Please, elaborate on following. Can they be used to control non-desired microorganisms in foods? Will that create any danger for human health? Do you see them being approved by FDA for food preservation? Since bacteria aver very smart and know how to build resistance against various stresses, what needs to be done to prevent resistance to bacteriophages?
    The bacteriophages can be used as food preservatives -in fact, they were approved by FDA. They create no threat to human health since they are active only against bacteria. However, they may induce lysis of the pathogen with additional release oftoxin(s). To avoid bacterial resistance, cocktails of different bacteriophages should be used.
  35. An intriguing death of Alexander the Great. How can the almost mysterious story lead us to a scientifically-sound assumption on the cause of his death?
    Legend has it that as Alexander entered Babylon, a flock ofravens exhibited odd behavior and then died at his feet. Shortly after, Alexander the Great died in Babylon (June 10 323BC) following a 2 week febrile illness. Symptoms included: fever with chills, thirsty, acute abdominal pain, and back pain at onset of fever, weakness that progressed to prostration, delirium, and terminal flaccid paralysis. Although his symptoms were most consistent with poliomyelitis and Guillan-Barre Syndrome, and some authors speculate about death from malaria, typhoid fever, parasites or poisoning, there is a possibility (based on the symptoms and the event described in the legend) that Alexander the Great may have died from West Nile Encephalitis almost 2,000 years before it was recognized as a human disease.
  36. Strep throat is a very unpleasant condition – not to mention that it can persist for a long time. What kind of bacteria cause this condition? Can it be always easily cured? If not, what kind of an alternative approach can be taken?
    Streptococcus pyogenesisthe microorganism that causes strep throat. Usually, antibiotics areprescribed to treat this condition. However, not all patients respond well to antibiotics. One of thealternative approaches that showed to be effective is a so-called strain replacement therapy. Thelactic acid bacteria strain active againstSt. pyogenescan be used to make yogurt or consumes as asupplement in the form of pills. These friendly bacteria will multiply in the throat and will compete withthe pathogen thus pushing it away from the ecological niche -replacing it. The friendly probiotic maybe stronger than the pathogen due to the production of natural antimicrobials such as weak organicacids (lactic acid) and bacteriocins and being a better competitor for the nutrients.
  37. Ugly face of a friendly bug: are these probiotics always friendly? What do you know about “bad probiotics”, including the “Utrecht case”?
    Probiotics may be bad,too. In fact, if the human subject is weakened or his/her immunesystem is compromised in any way, high dose bacteria administration can cause devastatingeffect on the human health. Recent clinical trial conducted in Utrecht (The Netherlands,reported in February 2008) addressed administration of probiotics to the patients with acutepancreatitis. There was an expected 6% death in the placebo group. However, the rate ofdeath in the probiotic-treated group was a striking 16%. Although the average death of ll-18%is reported in the literature, this striking difference allows assuming possible negative effectofprobiotics. In addition, some lactobacillus are known to cause cardio-vascular infections

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