Microbiology Lab Practical Midterm
Exam Question and answers rated A+
2025
Aseptic technique - correct answers Without contamination of the culture,
sterile medium, or the surroundings.
Koehler illumination steps - correct answers fully open condenser aperture
diaphragm rotate control ring to right.
Lower stage for slide
Nosepiece to 10x
Raise stage until course adjustment focus knob reaches positive stop, then
use fine adjustment to bring specimen in sharp focus
Adjust eyetubes for interpupillary distance and eye diff.
KOEHLER
1. slowly close the field diaphragm using the field diaphragm lever in the
microscope base. Iris leaves of field diaphragm will be in view.
2. Use condenser focusing knob, focus until leaves of field diaphragm are in
sharp focus.
3. Center the image of the field diaphragm by turning condenser centering
screws simultaneously. After centering, open field diaphragm until iris leaves
disappear beyond field of view, then STOP.
4. Close the condenser diaphragm until an acceptable balance between
contrast and resolution is reached. Condenser control ring has an index line
and scale for suggested starting setting for each objective.
