Chapter 3

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Microbiology
Chapter 3
Microbiology 205- Post-test Fall 2012
Grade levels:
College: Second year
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1

The _______ of a compound light microscope focuses light from the light source on the specimen.

Condenser lens OR condenser

2

Which of the following is the most convenient and appropriate unit for expressing the size of an average bacterial cell?

Micrometer

3

All of the following are visible through a compound light microscope except____.

0.02-AUM ribosome

4

Bacterial motility and flagellar movement can readily be viewed using transmission electron microscopy.

False

5

A____________ is equal to 0.000001m.

micrometer

6

Acid-fast Mycobacteria differ from non-acid-fast bacteria by the presence of ____. In the decolorizing step of the acid -fast stain, which reagent is used?

carbol fuchsin waxy material in their cell wall

7

When stained, bacteria in the genus Mycobacterium are ____. When using a 10x ocular lens and a 40x objective, the total magnification achieved is

acid-fast 400x

8

Which of the following is not a modification of a compound microscope?

electron microscope

9

Flagella are too ________ to be seen with the light microscope without adding a mordant.

small or thin

10

Immersion oil acts to decrease refraction of light rays and thus increase resolution.

True

11

In the Gram stain, if the decolorizing step is deleted, gram-negative cells will appear _______ at the completion of the staining procedure.

Purple

12

Magnification is the quality of the microscope that allows on to distinguish between two points that are very close together.

False

13

Place these structures of the compound light microscope in order that light passes through them on the way to the observer's eyes: (1) condenser,(2)ocular lens, (3) illuminator, (4)specimen, (5) objective lens.

3-1-4-5-2
Response feedback: The path of light begins with the illuminator, then passes through the condenser, the specimen, the objective lens, then then the ocular lens.

14

Bacterial smears must be heat-fixed before all staining procedures.

False

15

The ______ charge of a basic dye adheres to the ______ charge of bacterial cell surfaces.

positive;negative

16

The _____ is the part of the microscope that controls the amount of the light entering the condenser.

diaphragm

17

The Gram stain is important in medical microbiology because the results help physicians select appropriate antibiotics for treatment.

True

18

Which of the following kinds of microscopy would be most appropriate for viewing the shape and arrangement of pili or fimbriae on the surface of the bacterial cell?

scanning electron microscopy

19

Which of the following types of microscopy is most useful for viewing the internal structures of unstained specimens?

Phase-contrast

20

You are viewing a sputum smear that has been stained with an acid-fast stain. On this smear you see 5-Aum-long red cells. You can conclude that _______.

there are acid-fast bacteria in the specimen