MICROBIO 303 Test Exam quiz and
answers graded A+
Kohler Illumination - ANS✅✅1. fully rack up the condenser
2. focus on specimen with 10x
3. close the diaphragm (hexagon)
4. lower the condenser to until image is in optimal focus (strong hexagon)
5. center the hexagon
6. open diaphragm just enough so the light covers the whole field of view
phase contrast - ANS✅✅use for unstained living organisms
1. set up kholer
2. push annular stop in
3.increase the light if needed
4. use fine focus
oil immersion - ANS✅✅only use for 100x
1. focus on sample at lower x using kholer
2. rotate so that the oil immersion lens is almost over the specimen
3. add oil to the slide and rotate the lens on so it touches the oil
4. focus with fine adjustment away (
microscope maintenance - ANS✅✅-use lens paper only
functions of a streak plate - ANS✅✅1. to isolate single colonies to be characterized
2. to describe colonies on a morphological basis
3. source of pure inoculum for sub-culturing
micrometer - ANS✅✅1000uM long
absolute smallest tick at 10x=10uM
, absolute smallest tick at 40x=2.5uM
absolute smallest tick at 100x=1uM
aseptic technique - ANS✅✅-keep things 10-20cm close to the flame (except EtOH)
-don't keep things open longer than necessary
-clean spills with hyamine or bleach soaked paper towels
-vortex a broth culture before using it
Different Broth Recipes - ANS✅✅nutrient broth: beef extract + peptone
glucose mineral salts broth: salts + sugar
tryptic soy broth: tryptone, soytone, dextrose, salts
semi-enriched broth: glucose mineral salts + 1/10 nutrient broth
Anaerobic Culture Methods - ANS✅✅-boil for 10 minutes and seal with wax/mineral oil
-using reducing agents such as sodium thioglycolate with methylene blue indicator
-brewers anaerobic jar:
a) H + O2 reaction catalysed by heated platinum or unheated palladium. excess water absorbed by
CaCl2
b) distilled water + package containing catalyst
c) replace air with inert gas (vacuum needed)
disinfectants on microorganisms - ANS✅✅germicides: kill microorganism specifically or not
microstatic: inhibit growth but wont kill them, upon removal they will grow again
disinfectants: may be germicides or microstatic agents, not safe for medical use and only are used on
inanimate objects
antiseptics: like disinfectants but are applied on biological tissues
soap&water: reduces number of microorganisms on skin surface
alcohol: denatures proteins, extracts membrane lipids, dehydrating agent (antiseptic)
iodine (antiseptic): kills all types of bacteria, including spores
heavy metals (antiseptic): eg silver nitrate
detergents: cationic or anionic, eg quaternary ammonium salts
answers graded A+
Kohler Illumination - ANS✅✅1. fully rack up the condenser
2. focus on specimen with 10x
3. close the diaphragm (hexagon)
4. lower the condenser to until image is in optimal focus (strong hexagon)
5. center the hexagon
6. open diaphragm just enough so the light covers the whole field of view
phase contrast - ANS✅✅use for unstained living organisms
1. set up kholer
2. push annular stop in
3.increase the light if needed
4. use fine focus
oil immersion - ANS✅✅only use for 100x
1. focus on sample at lower x using kholer
2. rotate so that the oil immersion lens is almost over the specimen
3. add oil to the slide and rotate the lens on so it touches the oil
4. focus with fine adjustment away (
microscope maintenance - ANS✅✅-use lens paper only
functions of a streak plate - ANS✅✅1. to isolate single colonies to be characterized
2. to describe colonies on a morphological basis
3. source of pure inoculum for sub-culturing
micrometer - ANS✅✅1000uM long
absolute smallest tick at 10x=10uM
, absolute smallest tick at 40x=2.5uM
absolute smallest tick at 100x=1uM
aseptic technique - ANS✅✅-keep things 10-20cm close to the flame (except EtOH)
-don't keep things open longer than necessary
-clean spills with hyamine or bleach soaked paper towels
-vortex a broth culture before using it
Different Broth Recipes - ANS✅✅nutrient broth: beef extract + peptone
glucose mineral salts broth: salts + sugar
tryptic soy broth: tryptone, soytone, dextrose, salts
semi-enriched broth: glucose mineral salts + 1/10 nutrient broth
Anaerobic Culture Methods - ANS✅✅-boil for 10 minutes and seal with wax/mineral oil
-using reducing agents such as sodium thioglycolate with methylene blue indicator
-brewers anaerobic jar:
a) H + O2 reaction catalysed by heated platinum or unheated palladium. excess water absorbed by
CaCl2
b) distilled water + package containing catalyst
c) replace air with inert gas (vacuum needed)
disinfectants on microorganisms - ANS✅✅germicides: kill microorganism specifically or not
microstatic: inhibit growth but wont kill them, upon removal they will grow again
disinfectants: may be germicides or microstatic agents, not safe for medical use and only are used on
inanimate objects
antiseptics: like disinfectants but are applied on biological tissues
soap&water: reduces number of microorganisms on skin surface
alcohol: denatures proteins, extracts membrane lipids, dehydrating agent (antiseptic)
iodine (antiseptic): kills all types of bacteria, including spores
heavy metals (antiseptic): eg silver nitrate
detergents: cationic or anionic, eg quaternary ammonium salts
