Question 1

A student is looking at a bacterial specimen using the oil immersion lens, but has forgotten to put immersion oil on the slide. The specimen will appear

Accepted Answer

A)   smaller than it would if immersion oil was used.
B)   somewhat fuzzy and have poor resolution.
C)   the same as it would if the immersion oil was used.
D)   larger than it would if immersion oil was used.
E)   to have no color. B

Question 2

Which microscope takes advantage of differences in the refractive indexes of cell structures?

Accepted Answer

A)   compound light microscope
B)   phase-contrast microscope
C)   electron microscope
D)   darkfield microscope
E)   fluorescence microscope B

Question 3

The capsules and flagella of bacteria can be observed in gram -stained smears.

Accepted Answer

A) True 
 B)False  False

Question 4

If acid-fast bacteria are stained with the Gram stain, they will stain gram-negative.

Accepted Answer

A) True 
 B)False

Question 5

Which of the following is NOT true regarding the acid-fast stain?

Accepted Answer

A)   Acid-fast cells appear red in a completed acid-fast stain.
B)   It is used to identify members of the genus Mycobacterium.
C)   Non-acid-fast microbes appear blue in a completed acid-fast stain.
D)   Acid-fast cells retain the primary dye after treatment with acid -alcohol.
E)   If cells are acid-fast, they are gram-negative.

Question 6

The resolution of a microscope can be improved by changing the

Accepted Answer

A)   condenser.
B)   coarse adjustment.
C)   diaphragm.
D)   wavelength of light.
E)   fine adjustment.

Question 7

You are performing a Gram stain on gram-negative bacteria and you stop after the decolorizer step. What is the appearance of the bacteria at this point?

Accepted Answer

A)   purple
B)   red
C)   colorless
D)   brown

Question 8

In microscopy, the term resolution

Accepted Answer

A)   refers to the ability to distinguish fine structure and detail in a specimen.
B)   refers to magnification when using the electron microscope.
C)   is improved when longer wavelengths of light are employed.
D)   is only observed in stained specimens.
E)   is the same as the total magnification of a specimen.

Question 9

What is the total magnification of a specimen viewed with a 10x ocular lens and a 45x objective lens?

Accepted Answer

A)   4.5x
B)   45x
C)   100x
D)   10x
E)   450x

Question 10

The greater resolution of the electron microscope compared to the compound microscope is due to the longer wavelengths of the electrons used to examine specimens.

Accepted Answer

A) True 
 B)False

Question 11

You are performing a Gram stain on gram-negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point?

Accepted Answer

A)   purple
B)   red
C)   colorless
D)   brown

Question 12

You are working in a clinical laboratory and you need to examine an unstained urine sample for the presence of bacteria. What type of light microscope should you use to observe this specimen? Explain your answer.

Accepted Answer

The answer of You are working in a clinical laboratory...

Question 13

Which of the following pairs is mismatched?

Accepted Answer

A)   crystal violet  basic dye
B)   safranin  acid dye
C)   alcohol-acetone  decolorizer
D)   carbolfuchsin  basic dye
E)   iodine  mordant

Question 14

The purpose of the ocular lens is to

Accepted Answer

A)   magnify the image from the objective lens.
B)   decrease the refractive index.
C)   decrease the light.
D)   increase the light.
E)   improve resolution.

Question 15

Which microscope is used to observe viruses and the internal structure of thinly sectioned cells?

Accepted Answer

A)   brightfield microscope
B)   scanning electron microscope
C)   darkfield microscope
D)   fluorescence microscope
E)   transmission electron microscope

Question 16

The limit of resolution of the compound microscope illuminated with visible light is approximately
0.2 μm.

Accepted Answer

A) True 
 B)False

Question 17

In using this microscope, the observer does NOT look directly at an image through a lens.

Accepted Answer

A)   fluorescence microscope
B)   phase-contrast microscope
C)   compound light microscope
D)   darkfield microscope
E)   electron microscope

Question 18

This microscope produces an image of a light cell against a dark background; internal structures are NOT visible.

Accepted Answer

A)   phase-contrast microscope
B)   fluorescence microscope
C)   darkfield microscope
D)   electron microscope
E)   compound light microscope

Question 19

You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the first dye. What is the appearance of the bacteria at this point?

Accepted Answer

A)   purple
B)   red
C)   colorless
D)   brown

Question 20

Which of the following places the steps in the correct sequence? 1- Staining
2- Making a smear 3-Fixing

Accepted Answer

A)   3-2-1
B)   1-2-3
C)   1-3-2
D)   2-3-1
E)   The order is unimportant.

Exam 3: Observing Microorganisms Through a Microscope

A student is looking at a bacterial specimen using the oil immersion lens, but has forgotten to put immersion oil on the slide. The specimen will appear

Which microscope takes advantage of differences in the refractive indexes of cell structures?

The capsules and flagella of bacteria can be observed in gram -stained smears.

If acid-fast bacteria are stained with the Gram stain, they will stain gram-negative.

Which of the following is NOT true regarding the acid-fast stain?

The resolution of a microscope can be improved by changing the

You are performing a Gram stain on gram-negative bacteria and you stop after the decolorizer step. What is the appearance of the bacteria at this point?

In microscopy, the term resolution

What is the total magnification of a specimen viewed with a 10x ocular lens and a 45x objective lens?

The greater resolution of the electron microscope compared to the compound microscope is due to the longer wavelengths of the electrons used to examine specimens.

You are performing a Gram stain on gram-negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point?

You are working in a clinical laboratory and you need to examine an unstained urine sample for the presence of bacteria. What type of light microscope should you use to observe this specimen? Explain your answer.

Which of the following pairs is mismatched?

The purpose of the ocular lens is to

Which microscope is used to observe viruses and the internal structure of thinly sectioned cells?

The limit of resolution of the compound microscope illuminated with visible light is approximately 0.2 μm.

In using this microscope, the observer does NOT look directly at an image through a lens.

This microscope produces an image of a light cell against a dark background; internal structures are NOT visible.

You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the first dye. What is the appearance of the bacteria at this point?

Which of the following places the steps in the correct sequence? 1- Staining 2- Making a smear 3-Fixing