Deck 3: Observing Microorganisms Through a Microscope

Question 1

Simple staining is often necessary to improve contrast in this microscope.

A) Compound light microscope
B) Phase- contrast microscope
C) Darkfield microscope
D) Fluorescence microscope
E) Electron microscope

Answer 1

E

Question 2

The resolution of a microscope can be improved by changing the

A) Diaphragm.
B) Wavelength of light.
C) Fine adjustment.
D) Coarse adjustment.
E) Condenser.

Answer 2

B

Question 3

This microscope is used to see detail of a 300 nm virus.

A) Phase- contrast microscope
B) Darkfield microscope
C) DIC microscope
D) Fluorescence microscope
E) None of the above

Answer 3

E

Question 4

The light that hits the specimen is scattered and does not come directly from the light source in this microscope.

A) Fluorescence microscope
B) Electron microscope
C) Phase- contrast microscope
D) Compound light microscope
E) Darkfield microscope

Question 5

The signal molecule produced in quorum sensing is

A) Simple stain.
B) Counterstain.
C) Inducer.
D) Light.
E) None of the above.

Question 6

What structure does light pass through after leaving the condenser in a compound light microscope?

A) Objective lens
B) Specimen
C) Ocular lens
D) Illuminator

Question 7

Bacterial smears are fixed before staining to

A) Kill the bacteria.
B) Affix the cells to the slide.
C) Make their walls permeable.
D) A and B.
E) All of the above.

Question 8

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

A) Compound light microscope
B) Phase- contrast microscope
C) Darkfield microscope
D) Fluorescence microscope
E) Electron microscope

Question 9

You find colorless areas in cells in a Gram- stained smear. What should you do next?

A) An acid- fast stain
B) A flagella stain
C) A capsule stain
D) A simple stain
E) An endospore stain

Question 10

What Gram reaction do you expect from acid- fast bacteria?

A) Gram- negative
B) Gram- positive
C) Both gram- positive and gram- negative
D) Can't tell

Question 11

This microscope does not use a light.

A) Compound light microscope
B) Darkfield microscope
C) Phase- contrast microscope
D) Fluorescence microscope
E) Electron microscope

Question 12

Which of the following pairs is mismatched?

A) Scanning electron microscope - produces a three- dimensional image
B) Fluorescence microscope - uses a fluorescent light
C) Darkfield microscope - uses visible light
D) Scanning tunneling microscope - allows visualization of atoms
E) Confocal microscope - produces a three- dimensional image

Question 13

Figure 3.1

In Figure 3.1 line B points to the microscope's

A) ocular lens.
B) condenser.
C) illuminator.
D) objective lens.

Question 14

The appearance of gram- negative bacteria after completing the Gram stain.

A) Purple
B) Red
C) Colorless
D) Brown
E) None of the above

Question 15

This microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light.

A) Compound light microscope
B) Fluorescence microscope
C) Electron microscope
D) Darkfield microscope
E) Phase- contrast microscope

Question 16

The appearance of gram- positive bacteria after addition of the first dye in the Gram stain.

A) Purple
B) Red
C) Colorless
D) Brown
E) None of the above

Question 17

Assume you stain Bacillus by applying malachite green with heat and then counterstaining with safranin. Through the microscope, the green structures are

A) Capsules.
B) Flagella.
C) Cell walls.
D) Endospores.
E) Can't tell.

Question 18

Van Leeuwenhoek's microscope was a(n)

A) Confocal microscope.
B) Simple microscope.
C) Electron microscope.
D) Phase- contrast microscope.
E) None of the above.

Question 19

The purpose of the ocular lens is to

A) Increase the light.
B) Magnify the image from the objective lens.
C) Improve resolution.
D) Decrease the refractive index.
E) None of the above.

Question 20

In this microscope, the observer does not look at an image through a lens.

A) Compound light microscope
B) Phase- contrast microscope
C) Darkfield microscope
D) Fluorescence microscope
E) Electron microscope

Question 21

Image looks like a negative stain in this microscope:

A) Phase- contrast microscope
B) Fluorescence microscope
C) Darkfield microscope
D) DIC microscope
E) None of the above

Question 22

Which of the following pairs is mismatched?

A) Safranin - acid dye
B) Iodine - mordant
C) Alcohol- acetone - decolorizer
D) Crystal violet - basic dye
E) None of the above

Question 23

The appearance of gram- positive bacteria after adding the counterstain in the Gram stain.

A) Purple
B) Red
C) Colorless
D) Brown
E) None of the above

Question 24

This microscope is used to see intracellular detail.

A) Phase- contrast microscope
B) Fluorescence microscope
C) DIC microscope
D) Darkfield microscope
E) None of the above

Question 25

Figure 3.1

In Figure 3.1 line A points to the microscope's

A) condenser.
B) objective lens.
C) ocular lens.
D) illuminator.

Question 26

You suspect a 100 nm structure is present in a cell. Which of the following provides the lowest magnification that you can use to see this structure?

A) Darkfield microscope
B) Brightfield microscope
C) Transmission electron microscope
D) Phase- contrast microscope
E) Scanning electron microscope

Question 27

The counterstain in the acid- fast stain is

A) A mordant.
B) A negative stain.
C) A basic dye.
D) An acid dye.
E) Necessary to determine acid- fast cells.

Question 28

This microscope is used to see internal structures of cells in a natural state.

A) Compound light microscope
B) Phase- contrast microscope
C) Darkfield microscope
D) Fluorescence microscope
E) Electron microscope

Question 29

Which of the following is not equal to 1 m?

A) 109 nm
B) 106 µm
C) 10 dm
D) 100 mm
E) None of the above

Question 30

Which of the following pairs is mismatched?

A) Acid- alcohol - decolorizer
B) Alcohol - acetone- decolorizer
C) Iodine - mordant
D) Gram- negative bacteria - negative stain
E) None of the above

Question 31

Place the steps of the Gram stain in the correct order:
1- Alcohol- acetone; 2- Crystal violet; 3- Safranin; 4- Iodine.

A) 2- 4- 1- 3
B) 4- 3- 2- 1
C) 1- 2- 3- 4
D) 2- 1- 4- 3
E) 1- 3- 2- 4

Question 32

The counterstain in the Gram stain is

A) A mordant.
B) An acid dye.
C) A negative stain.
D) A basic dye.
E) Necessary to determine the Gram reaction.

Question 33

This microscope takes advantage of differences in the refractive indexes of cell structures.

A) Darkfield microscope
B) Fluorescence microscope
C) Compound light microscope
D) Electron microscope
E) Phase- contrast microscope

Question 34

Which of the following is not correct?

A) 1 µm = 10^{- 3} mm
B) 1 nm = 10^{- 6} µm
C) 1 µm = 10^{- 6} m
D) 1 µm = 10³ nm
E) 1 nm = 10^{- 9} m

Question 35

The appearance of gram- negative bacteria after addition of the decolorizing agent in the Gram stain.

A) Purple
B) Red
C) Colorless
D) Brown
E) None of the above

Question 36

Which of the following microscopes uses visible light?

A) Scanning electron microscope
B) Fluorescence microscope
C) Scanning acoustic microscope
D) Confocal microscope
E) DIC

Question 37

Figure 3.1

In Figure 3.1 line C points to the microscope's

A) objective lens.
B) illuminator.
C) condenser.
D) ocular lens.

Question 38

Cells are differentiated after which step in the Gram stain?

A) Alcohol- acetone
B) Crystal violet
C) Iodine
D) Safranin

Question 39

The best use of a negative stain is

A) To determine cell size.
B) To determine cell shape.
C) To see endospores.
D) To determine Gram reaction.
E) A and B

Question 40

The appearance of gram- negative bacteria after addition of the mordant in the Gram stain.

A) Purple
B) Red
C) Colorless
D) Brown
E) None of the above

Question 41

The purpose of a mordant in the Gram stain is

A) To prevent the crystal violet from leaving the cells.
B) To make the bacterial cells larger.
C) To make the flagella visible.
D) To remove the simple stain.
E) None of the above.

Question 42

This microscope achieves the highest magnification and greatest resolution.

A) Compound light microscope
B) Phase- contrast microscope
C) Darkfield microscope
D) Fluorescence microscope
E) Electron microscope

Question 43

This microscope uses two beams of light to produce a three- dimensional, color image.

A) DIC microscope
B) Darkfield microscope
C) Fluorescence microscope
D) Phase- contrast microscope
E) None of the above