UNE MICRO LAB FINAL EXAM AND
ALL CORRECT ANSWERS 2025-2026
UPDATED.
kirby bauer diffusion test - Answer most common method of assessing bacteria antibiotic
resistance
filter paper disks containing antibiotics are placed on agar plate with bacteria, antibiotic diffuses
away from disk, as bac grow they will be inhibited in regions where the antibiotic concentration
is above what the microorganisms can handle
areas where antibiotic concentration is low will allow for bac growth - growth will lead to
growth of lawn with zone around each disk called zone of inhibition
kirby bauer diffusion test interpretation - Answer zone of inhibition
- measured in millimeters
- dependent on bac sensitivity to antibiotic and physical antibiotic properties
staining techniques - Answer simple stain: one dye reveals shape, size, and arrangement
direct stain: type of simple stain, only bacterial cell is colored leaving background clear and
colorless
negative stain: type of simple stain, cell is unstained and appears bright against dark-stained
environment
differential stain: 2 or more dyes used, allows to view cell morph and flagella, capsules, and
endospores
Gram stain procedure - Answer 1. Primary stain (Crystal violet- a basic stain, purple dye)
2. Mordant (Gram's iodine- I2 + KI)
(something that helps fix dye on or in a cell but does not itself contribute color)
3. decolorizing agent (Ethanol or acetone) (dehydrates gram pos cell, traps in dye, washes dye
from gram neg)
4. Counterstain (Safranin- a basic stain) ( no effect on gram pos, causes gram neg to be pink)
, 3 main types of microscopes - Answer optical or light microscopes: uses reflected light and
series of two or more convex lenses to magnify and focus (compound)
electron
scanning probe
parts of microscope - Answer ocular lens: short, look through, eye piece (10x or 15x power)
objective lens: closest to stage, held by turret or revolving nose piece (4x, 10, 40x) - 100x is oil
immersion lens
condenser: sit below stage, focuses light from illuminator onto slide
diaphragm: sits below stage and condenser, lets little light through, varies the field for viewing
of specimen
depth of field - Answer distance range in focus at a given time (dependent on total mag
factor)
proper aseptic technique - Answer techniques to prevent the accidental or inadvertent
spread of microorganisms beyond the intended work surface (maintain safety, isolate pure
cultures, prevent spread of unwanted microbes)
1. wash hands
2. sterilize with 10% bleach solution or bleach based cleaner
3. sterilize equipment (open flame or isopropyl alc)
4. incubate plates inverted or agar side up
streak plate isolation - Answer Bacteria transferred from plate-to-plate or liquid-to-plate
using heat-sterilized metal loop.
ISOLATES 1 COLONY
FOV (field of view) calculation - Answer measure diameter of length of field from one of the
circle to the other
ALL CORRECT ANSWERS 2025-2026
UPDATED.
kirby bauer diffusion test - Answer most common method of assessing bacteria antibiotic
resistance
filter paper disks containing antibiotics are placed on agar plate with bacteria, antibiotic diffuses
away from disk, as bac grow they will be inhibited in regions where the antibiotic concentration
is above what the microorganisms can handle
areas where antibiotic concentration is low will allow for bac growth - growth will lead to
growth of lawn with zone around each disk called zone of inhibition
kirby bauer diffusion test interpretation - Answer zone of inhibition
- measured in millimeters
- dependent on bac sensitivity to antibiotic and physical antibiotic properties
staining techniques - Answer simple stain: one dye reveals shape, size, and arrangement
direct stain: type of simple stain, only bacterial cell is colored leaving background clear and
colorless
negative stain: type of simple stain, cell is unstained and appears bright against dark-stained
environment
differential stain: 2 or more dyes used, allows to view cell morph and flagella, capsules, and
endospores
Gram stain procedure - Answer 1. Primary stain (Crystal violet- a basic stain, purple dye)
2. Mordant (Gram's iodine- I2 + KI)
(something that helps fix dye on or in a cell but does not itself contribute color)
3. decolorizing agent (Ethanol or acetone) (dehydrates gram pos cell, traps in dye, washes dye
from gram neg)
4. Counterstain (Safranin- a basic stain) ( no effect on gram pos, causes gram neg to be pink)
, 3 main types of microscopes - Answer optical or light microscopes: uses reflected light and
series of two or more convex lenses to magnify and focus (compound)
electron
scanning probe
parts of microscope - Answer ocular lens: short, look through, eye piece (10x or 15x power)
objective lens: closest to stage, held by turret or revolving nose piece (4x, 10, 40x) - 100x is oil
immersion lens
condenser: sit below stage, focuses light from illuminator onto slide
diaphragm: sits below stage and condenser, lets little light through, varies the field for viewing
of specimen
depth of field - Answer distance range in focus at a given time (dependent on total mag
factor)
proper aseptic technique - Answer techniques to prevent the accidental or inadvertent
spread of microorganisms beyond the intended work surface (maintain safety, isolate pure
cultures, prevent spread of unwanted microbes)
1. wash hands
2. sterilize with 10% bleach solution or bleach based cleaner
3. sterilize equipment (open flame or isopropyl alc)
4. incubate plates inverted or agar side up
streak plate isolation - Answer Bacteria transferred from plate-to-plate or liquid-to-plate
using heat-sterilized metal loop.
ISOLATES 1 COLONY
FOV (field of view) calculation - Answer measure diameter of length of field from one of the
circle to the other
