micro practice exam 3

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andreathors16
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143268
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micro practice exam 3
Updated:
2012-03-29 20:26:10
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microbiology
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test a
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  1. if a single bacterium replicated every 20 min, how many bacteria will be present after 120 min?
    64
  2. which phase of growth curve where microbial population is the slowest or the least
    stationary phase
  3. during the lag phase
    cells are engaged in intense enzymatic activity
  4. reduce bacterial concentrations while not affecting flavor of a fruit drink.
    pasteurization
  5. fastest way to measure bacterial growth?
    turbidity
  6. trace elements are added to microbiological media to provide
    enzyme cofactors
  7. after dilution of cells in a plate count, no colonies are observed? what happened?
    • there were no cells in the culture
    • media did no support growth
    • the wrong dilution was plated
    • incubation conditions were incorrect
  8. a chemical requirement of ALL bacteria
    • nitrogen, mineal element, sulfur, carbon
    • not 02
  9. superoxide dismutase nutralizes which form of toxic oxygen
    szuperoxide free radicals
  10. bacteria require nitrogen for synthesis of
    protiens
  11. what enzyme disposes of hydrogen peroxide?
    catalase
  12. medium with agar peptone and beef heart extract is
    a complex medium
  13. component of a defined media
    • magnesium chloride
    • potassium nitrate
    • ammonium sulfate
    • glucose
    • not: soy tryptone
  14. toxic forms of oxygen
    • hydrogen peroxide
    • peroxide anion
    • superoxide free radicals
    • singlet oxygen
    • not: molecular oxygen
  15. type of media that suppress the growth of unwanted bacteria/encourages the growth of desired microbes
    selective media
  16. sterilization
    destruction of all life form
  17. first disinfectant by lister was
    phenol
  18. oxdizing agents
    • ozone
    • bleech
    • iodine
    • hydrogen peroxide
    • not: phenol
  19. anispetic is used to remove microbes from
    skin prior to injection
  20. term that refers to an agent that inhibits growth of bacteria
    bacteriostatic
  21. major target action of antimicrobials
    • cell membrane, protien, nucleic acid, enzymes
    • not: flagella
  22. which bacteria is heardest to kill
    clostridium endospores
  23. radiation least effective in killing microbes
    microwaves
  24. alcohol is most effective when used as a solution of what concentration
    70%
  25. charicteristics of autoclave
    • most heat, high temp, high pressure, sterilize with endosporess
    • Not: long hours
  26. bactericidal
    • ionizing radiation
    • incineration
    • autoclaving
    • ethylene oxide gas
    • not: lyophilization
  27. best method for sterilization of enzyme solution
    filtration
  28. bactericidal effect of UV light damages the
    DNA
  29. heavy metals
    • zinc chloride, copper sufate, mercurochrome, silver sulfadiazine
    • not: benzoyl peroxide
  30. antimicrobial
    • calcium propionate, sodium benzoate, sorbic acid, potassium sorbate
    • not:xanthan
  31. first antibiotic discovered was
    quinine
  32. inhibits cell wall synthesis
    cephlpsporin

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