Micro Ch 6 – Flashcards

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The ability of microbes to utilize N2, as a nitrogen source is called....
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nitrogen fixation
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bacterial growth refers to an increase in the ____ of bacterial cells
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number
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an unknown organism grows at the top of a tube of thioglycolate broth.. This organism is _____ for oxygen requirements
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aerobe
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salt agar tends to inhibit the growth of most organisms except staph. this is an example of _____ media
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selective
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this method , cells are added to melted agar, and poured into a dish
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pour plate method
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bacteria reequire nitrogen for the synthesis of
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proteins
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what do all these bacteria have in common? Bacteria in the rumen of cattle, sheep bacteria in a sewage treatment plant, bacteria growing in the middle ear of chronic otitis, bacteria on the teeth
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bacteria are most likely growing in biofilms...
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an organism that grows both in the presence and the absence of o2 and uses oxygen when it is avail
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facultative anaerobe
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culture medium consisting of agar, peptone, and beef heart extract..
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complex medium
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niacin, when added to a medium would be considered
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organic growth factor
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martian soil is inoculated into a glucose-containing med. the radioactive form of c, is used in the glucose. after incubation for 5 days, what provides evidence suggesting there is life on mars
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radioactive carbon dioxide (conversion of c as glucose to c as co2 indicates the metabolism...thus life
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a medium containing lauryl sulfate inhibits growth of g-pos bacteria.. theis medium is
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selective,
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a medium that inhibits the growth of certain bacteria while permitting the growth of others is described as
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selective
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to look for bacteria that degrade petroleum, a culture med contining crude oil, sodium nitrate, phosphate buffer and magnesium sulfate is inoculated with soil.. this medium is
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complex medium
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if there is not a formula for crude oil, the medium would be described as
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complex medium
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what is the third step in binary fission
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inward growth of membrane
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which biosafety leve, has ... open lab benchtop, gloves, lab coat, and face prtotection
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2
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psychrotrophic org are often responsible for food spoilage in refrigerated foods, t or f
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true
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t or f... adding salts to a solution increases osmotic pressure and is used to preserve food
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true
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microaerophiles do not require oxygen for growth t or f
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false
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aerotolerant organisms can grow in the presence of oxygen because their cell wall protects them from toxic prod of oxygen... t or f
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false
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microaerophiles do not require oxygen for growth
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false
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in a direct microscopic cnt, dead cells are easily differenctiated from live cells t or f
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false
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why is homemade potato salad refig overnight and served without any cooling on a warm day bad?
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lg volume of pot salad is probably never completely cooled before serving. second not keeping it cold the next day will allow more bactria to grow.
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what is the disadvantage of using turbidity to estimate the number of viable bact cells in a broth
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turbidity method counts dead celss as well as those that are viable and turbidity cannot be used on very dilute population
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slower growing bact would have a ____ slope than those with a faster generation time
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greater slope (therefore; faster-growing bacteria would have a greateater slope than would those with a slw gen time
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t or f, psychrotrophic org are often responsible for food spoilage in refrigerator
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true
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adding salts to a solution increases the osmotic press and is used as a preservative t or f
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true
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microaerophiles do not require oxygen for growth
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false
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aerotolerant org can grow in a the presence of oxygen because their cell wall protects them from toxic products of oxygen
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false
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during the stationary phase, bacteria cont to undergo binary fission
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true
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candle jars work well for cultivating anaerobic bacteria t or f
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false
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when the spread plate tech is used to inoculate culture media some colonies form within the agar- t or f
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false
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in a direct microscopic cnt, dead cells are easily diff from live t or f
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false
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turbidity or cloudiness of a cell culture measured by spectophotometry is useful in detecting sm amt of microbial contamination in liq t or f
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false
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cells growing in a rich med will have a steaper log phase slope than will those growing in a nutrient-poor med t or f
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true
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shrinking of the cells cytoplasm in response to osmotic loss is called
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plasmolysis
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the enzyme ___ catalyzes the conversion of peroxide to water and oxygen...
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catalase
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the ___ is the most common tech used to obtain pure cultures of microbes (3 words)
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streak plate method
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bacterial growth refers to an increase in the _____
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number of bacterial cells
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an unknown org grows at the top of a tube of thioglycolate broth, the org is best described as..... for oxygen req
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aerobe
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salt agar tends to inhibit the growth of most organisms except staph.. this is ____ media
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selective media
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in a ____ cells are added to melted agar
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pour plate
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a type of cell to cell communication that allows bact growing in biofilms to communicate and coordinate their activity is known as ____
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quorum sensing
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in a pour pl tech, 32 bacterial colonies are counted on the 10 (-2) dilution of milk... how many bacteria were in the org milk
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3200
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infections concerd with biofilms ... the bacteria in biofilms are more likely to be __________
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resistant to antibiotics
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what tech will allow you to get isolated colonies on agar
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useing a streak plate technique to inocultae
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a medium containing lauryl sulfate inhibits growth of g-pos bacteria.. this medium is ___-
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selective
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s-s agar inhibits g-pos bacteria. on this medium is ______
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both selective and differential
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a bacterial species that grows fastest at 55c, which means it is a ______
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thermophile
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a _____ would be the most practical way to determine the number of bacteria in cottage cheese
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plate cnt
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nitrogen will be found in proteins, which include ____
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enzymes
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describe binary fission steps
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after dna rep and cell elongation the membrane grow inward between the 2 new formed cells
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clostridium can be cultured in an anaerobic incubator or in the presence of atmospheric oxygen if thioglycolate is added to the nugrient broth the addition of thiog... makes the medium
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reduced
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bacteria grown with a campypak that produces 5% co2 and 15% o2, this bacterium is a ____
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microaerophile (atmosphere provided by the campypak has reduced lev of o2 perfect for microaerophile)
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bacteria that spoil food in the fridge are most likely _____, they prefer 20C
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psychrotrophs
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if 52 bacterial colonies grow on agar inoculated with 1:1000 of hamburger hwo many bact originated
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52,000
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