UTA MICROBIOLOGY 2460 REVIEW EXAM 2
QUESTIONS AND ANSWERS SURE A+
✔✔A bacterium that thrives in a soda lake where the average pH is 10.5 can be
classified as a(n) ________. - ✔✔alkaliphile
✔✔Lactobacillus acidophilus grows best at pH 4.5. It is considered a(n) ________. -
✔✔acidophile
✔✔A bacterium that thrives in the Great Salt Lake but not in fresh water is probably a
________. - ✔✔halophile
✔✔Blood agar contains many unspecified nutrients, supports the growth of a large
number of bacteria, and allows differentiation of bacteria according to hemolysis
(breakdown of blood). The medium is ________ and ________. - ✔✔complex and
differential
✔✔What is the microbial death curve? - ✔✔measure of the percent killed, usually
logarithmic
✔✔What is the thermal death point? - ✔✔lowest temperature that kills all microbes in 10
minutes
, ✔✔What is the thermal death time? - ✔✔the length of time to kill all microbes at a
certain temperature
✔✔What is high-temp short-time pasteurization? - ✔✔milk is heated to 72 C for 15
seconds and then refridgerated
✔✔What is ultra high temperature pasteurization? - ✔✔milk is heated to 138 C for 2
seconds and then is shelf stable
✔✔What is pascalization? - ✔✔high pressure used in food industry to kill microbes
hyperbaric chambers to treat hypoxia
✔✔What is desiccation? - ✔✔drying or dehydration
low water activity
✔✔What is ionizing radiation? - ✔✔high energy radiation that enters the cell and
disrupts structures like DNA
x-rays and gamma rays
can sterilize non-autoclavable items
✔✔What is non-ionizing radiation? - ✔✔high energy radiation that doesn't penetrate
glass or plastic, UV irradiation forms thymine dimers in DNA causing lethal mutations
✔✔What is sonication? - ✔✔high frequency sound waves to disrupt cell structure,
causes bubbles to form inside cells and induce lysis
✔✔What are phenols? - ✔✔benzene ring with a -OH group
denatures proteins and membranes
✔✔What are examples of phenols? - ✔✔carbolic acid, lysol (old formula), triclosan
✔✔What are heavy metals used for? - ✔✔binds to and inhibits proteins but also harms
host if it bio-accumulates
✔✔What are examples of heavy metals? - ✔✔mercury, silver, copper sulfate, zinc
✔✔What are halogens used for? - ✔✔used for disinfection and dental care
✔✔What are examples of halogens? - ✔✔iodine, chlorine, bromine, fluorine
✔✔What are alcohols used for? - ✔✔used as disinfectants and antiseptics
disrupts membranes, denatures proteins
QUESTIONS AND ANSWERS SURE A+
✔✔A bacterium that thrives in a soda lake where the average pH is 10.5 can be
classified as a(n) ________. - ✔✔alkaliphile
✔✔Lactobacillus acidophilus grows best at pH 4.5. It is considered a(n) ________. -
✔✔acidophile
✔✔A bacterium that thrives in the Great Salt Lake but not in fresh water is probably a
________. - ✔✔halophile
✔✔Blood agar contains many unspecified nutrients, supports the growth of a large
number of bacteria, and allows differentiation of bacteria according to hemolysis
(breakdown of blood). The medium is ________ and ________. - ✔✔complex and
differential
✔✔What is the microbial death curve? - ✔✔measure of the percent killed, usually
logarithmic
✔✔What is the thermal death point? - ✔✔lowest temperature that kills all microbes in 10
minutes
, ✔✔What is the thermal death time? - ✔✔the length of time to kill all microbes at a
certain temperature
✔✔What is high-temp short-time pasteurization? - ✔✔milk is heated to 72 C for 15
seconds and then refridgerated
✔✔What is ultra high temperature pasteurization? - ✔✔milk is heated to 138 C for 2
seconds and then is shelf stable
✔✔What is pascalization? - ✔✔high pressure used in food industry to kill microbes
hyperbaric chambers to treat hypoxia
✔✔What is desiccation? - ✔✔drying or dehydration
low water activity
✔✔What is ionizing radiation? - ✔✔high energy radiation that enters the cell and
disrupts structures like DNA
x-rays and gamma rays
can sterilize non-autoclavable items
✔✔What is non-ionizing radiation? - ✔✔high energy radiation that doesn't penetrate
glass or plastic, UV irradiation forms thymine dimers in DNA causing lethal mutations
✔✔What is sonication? - ✔✔high frequency sound waves to disrupt cell structure,
causes bubbles to form inside cells and induce lysis
✔✔What are phenols? - ✔✔benzene ring with a -OH group
denatures proteins and membranes
✔✔What are examples of phenols? - ✔✔carbolic acid, lysol (old formula), triclosan
✔✔What are heavy metals used for? - ✔✔binds to and inhibits proteins but also harms
host if it bio-accumulates
✔✔What are examples of heavy metals? - ✔✔mercury, silver, copper sulfate, zinc
✔✔What are halogens used for? - ✔✔used for disinfection and dental care
✔✔What are examples of halogens? - ✔✔iodine, chlorine, bromine, fluorine
✔✔What are alcohols used for? - ✔✔used as disinfectants and antiseptics
disrupts membranes, denatures proteins
