SERIES MICROBIOLOGY LAB MIDTERM COMPLETE QUESTIONS AND CORRECT ANSWERS | GRADED AND THE LATEST SERIES

2025-2026 SERIES
MICROBIOLOGY LAB MIDTERM COMPLETE
QUESTIONS AND CORRECT ANSWERS | GRADED
AND THE LATEST SERIES
Compound microscope


Ans: 1. Ocular-eyepiece lens (usually 10x)
2. Objective-nosepiece lenses (commonly 4x, 10x, 45x, and 100x)


Question: At what magnification do you use the oil immersion technique?


Ans: 100x.


Question: Total Magnification =


Ans: Magnification (Objective) x Magnification (Ocular)


Question: Important Parts of the Microscope


Ans: Framework, Stage, and Lens System


Question: Framework


Ans: Arm and base are the structural parts of the microscope which support the
basic frame.


Question: Stage


Ans: Holds the slide. The mechanical stage clamps the slide and moves the slide
around the stage.

, 2025-2026 SERIES
Question: Lens System


Ans: Oculars, Objective, and Condenser


Question: Oculars


Ans: Eyepiece lenses (usually 10x magnification)


Question: Objectives


Ans: Lenses attached to rotatable nosepiece, common magnification of 4x, 10x,
45x and 100x.


Question: Parfocalized microscope focusing adjustments are not to be made

when...


Ans: changing the objective lenses.


Question: The oil has approximately the same refractive index as glass to

prevent...


Ans: light loss due to diffraction (bending of light rays) which would occur if light
traveled from one refractive index to another (eg. glass to air)


Question: As magnification of the objective lens increases...


Ans: the working distance decreases.


Question: Working distance

, 2025-2026 SERIES
Ans: distance between the object on slide and the objective lens, when in focus.


Question: Condenser


Ans: directs light towards the objective lens in bright field microscopy.


Question: In dark field microscopy, the condenser...


Ans: directs light at oblique angles away from the objective lens in a manner that
allows only objects in the field of view to redirect or scatter light into the objective
lens. This causes objects to appear white on a dark field.


Question: Iris Diaphragm


Ans: lever located in the condenser that adjusts the diameter of the cone of light
so that it just fills the objective lens.


Question: As you close down the Iris Diaphragm...


Ans: 1. The light intensity decreases
2. Contrast improves
3. Depth of field increases
4. Limit Resolution (with oil immersion lens)


Question: Resolution