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Levin Bio 203A Midterm May 2, 2019
1. If your microscope has an objective lens of 200X magnification and an ocular lens of
10X magnification, what is the total magnification?
A. 200X
B. 210X
C. 1000X
D. 2000X
2. What is the purpose of putting oil on a microscope slide
A. It focuses light into every lens
B. It limits light refraction after the light passes through the glass slide
C. It makes the sample on the slide look bigger
D. It reflects light back so too much light isn’t entering the objective?
3. What does it mean when bacteria are inoculated?
A. They are placed into broth or onto an agar plate
B. They are placed on a slide for staining
C. All of the bacteria are removed
D. They are preserved by freezing
4. If you incubate a nutrient broth liquid medium for 24 hours, and observe bacterial
growth, what would be the appearance of the medium due to the growth? (Best answer)
A. Yellow
B. Turbid
C. Containing many colonies
D. The medium would remain clear cause bacteria are so small
5. When sedimentation of bacteria occurs, what is the appearance of the medium?
A. Bacteria grow at the surface
B. Bacteria settle at the bottom
C. Bacteria form small clusters that float
D. Bacteria are suspended throughout the medium
6. Semisolid agar deeps are used to show whether bacteria…….. All that apply.
A. Require oxygen
B. Can grow in the absence of oxygen
C. Are motile
Levin Bio 203A Midterm May 2, 2019
D. Are gram positive or negative
E. Can use photosynthesis
7. What is the reason a petri dish should not be left open when you are not inoculating it?
A. Contamination
B. The agar drying out
C. Bacteria that die in the presence of oxygen will die
D. Moisture will accumulate on the surface of the agar
E. Light will cause the bacteria to mutate
8. If bacteria form a pellicle in a nutrient broth, what does that say about the bacteria?
A. It does not use oxygen
B. It requires oxygen
C. It floats in liquid
D. It is motile
E. It has a capsule
9. Why is agar used on a petri dish?
