FREE Chapter 3 Observing Microorganisms Through a Microscope My Nursing Test Banks

Microbiology: An Introduction, 12e, (Tortora)

Chapter 3   Observing Microorganisms Through a Microscope

3.1   Multiple-Choice Questions

1) Which of the following is NOT equal to 1 mm?

A) 0.001 m

B) 106 nm

C) 0.1 cm

D) 100 m

E) 10-3 m

Answer:  D

Section:  3.1

Blooms Taxonomy:  Knowledge

Learning Outcome:  3.1

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

A) ocular lens

B) objective lens

C) specimen

D) illuminator

Answer:  C

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.2

3) Which of the following pairs is mismatched?

A) nigrosin negative stain

B) methylene blue simple stain

C) acidic dye capsule stain

D) basic dye negative stain

E) crystal violet simple stain

Answer:  D

Section:  3.3

Blooms Taxonomy:  Analysis

ASMcue Outcome:  8.1

Learning Outcome:  3.7

4) Which of the following places the steps of the Gram stain in the correct order?

1-Alcohol-acetone

2-Crystal violet

3-Safranin

4-Iodine

A) 1-2-3-4

B) 2-1-4-3

C) 2-4-1-3

D) 4-3-2-1

E) 1-3-2-4

Answer:  C

Section:  3.3

Blooms Taxonomy:  Application

ASMcue Outcome:  8.1

Learning Outcome:  3.9

5) Which of the following pairs is mismatched?

A) alcohol-acetone decolorizer

B) crystal violet basic dye

C) safranin acid dye

D) iodine mordant

E) carbolfuchsin basic dye

Answer:  C

Section:  3.3

Blooms Taxonomy:  Analysis

ASMcue Outcome:  8.1

Learning Outcome:  3.7

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

A) It is used to identify members of the genus Mycobacterium.

B) Acid-fast cells retain the primary dye after treatment with acid-alcohol.

C) If cells are acid-fast, they are gram-negative.

D) Acid-fast cells appear red in a completed acid-fast stain.

E) Non-acid-fast microbes appear blue in a completed acid-fast stain.

Answer:  C

Section:  3.3

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  8.1

Learning Outcome:  3.10

7) The purpose of a mordant in the Gram stain is to

A) remove the simple stain.

B) make the bacterial cells larger.

C) make the flagella visible.

D) prevent the crystal violet from leaving the cells.

E) make gram-negative cells visible.

Answer:  D

Section:  3.3

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  8.1

Learning Outcome:  3.10

8) Which of the following places the steps in the correct sequence?

1-Staining

2-Making a smear

3-Fixing

A) 1-2-3

B) 3-2-1

C) 2-3-1

D) 1-3-2

E) The order is unimportant.

Answer:  C

Section:  3.3

Blooms Taxonomy:  Application

ASMcue Outcome:  8.1

Learning Outcome:  3.8

9) The negative stain is used to

A) visualize endospores.

B) determine Gram reaction.

C) determine flagella arrangement.

D) visualize capsules.

E) determine cell size.

Answer:  E

Section:  3.3

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.11

10) Simple staining is often necessary to improve contrast in which microscope?

A) compound light microscope

B) phase-contrast microscope

C) darkfield microscope

D) fluorescence microscope

E) electron microscope

Answer:  A

Section:  3.3

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.8

11) Which 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

Answer:  B

Section:  3.2

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  2.1

Learning Outcome:  3.4

12) Which microscope uses visible light?

A) confocal microscope

B) differential interference contrast microscope

C) fluorescence microscope

D) scanning acoustic microscope

E) scanning electron microscope

Answer:  B

Section:  3.2

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  2.1

Learning Outcome:  3.4

13) Which 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

Answer:  E

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.4

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

A) compound light microscope

B) phase-contrast microscope

C) darkfield microscope

D) fluorescence microscope

E) electron microscope

Answer:  E

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.5

15) 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

Answer:  C

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.4

16) A virus measures 100 nm in length. What is its length in m?

A) 10 m

B) 1 m

C) 0.1 m

D) 0.01 m

E) 0.001 m

Answer:  C

Section:  3.1

Blooms Taxonomy:  Application

Learning Outcome:  3.1

17) Which of the following is never useful for observing living cells?

A) phase-contrast microscope

B) darkfield microscope

C) scanning acoustic microscope

D) scanning electron microscope

E) brightfield microscope

Answer:  D

Section:  3.2

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  2.1

Learning Outcome:  3.5

18) A microorganism measures 5 m in length. Its length in mm would be

A) 500 mm.

B) 50 mm.

C) 0.5 mm.

D) 0.05 mm.

E) 0.005 mm.

Answer:  E

Section:  3.1

Blooms Taxonomy:  Application

Learning Outcome:  3.1

19) Which of the following correctly traces the path of light through the compound microscope?

A) light source; condenser; specimen; objective lens; ocular lens

B) condenser; light source; specimen; ocular lens; objective lens

C) light source; specimen; condenser; objective lens; ocular lens

D) condenser; light source; specimen; objective lens; ocular lens

E) light source; condenser; objective lens; specimen; ocular lens

Answer:  A

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.2

20)  Figure 3.1

In Figure 3.1, line c points to the microscopes

A) illuminator.

B) condenser.

C) ocular lens.

D) objective lens.

Answer:  B

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.2

21) Which microscope can be used to visualize DNA or botulinum toxin?

A) compound light microscope

B) phase-contrast microscope

C) scanning tunneling microscope

D) confocal microscope

E) scanning electron microscope

Answer:  C

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.6

22) Which microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light?

A) compound light microscope

B) phase-contrast microscope

C) darkfield microscope

D) fluorescence microscope

E) electron microscope

Answer:  D

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.4

23) Which microscope is most useful for visualizing a biofilm?

A) compound light microscope

B) phase-contrast microscope

C) fluorescence microscope

D) scanning acoustic microscope

E) transmission electron microscope

Answer:  D

Section:  3.2

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  2.1

Learning Outcome:  3.6

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

A) compound light microscope

B) phase-contrast microscope

C) darkfield microscope

D) fluorescence microscope

E) electron microscope

Answer:  B

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.4

25) 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?

A) purple

B) red

C) colorless

D) brown

Answer:  A

Section:  3.3

Blooms Taxonomy:  Application

ASMcue Outcome:  8.1

Learning Outcome:  3.9

26) 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?

A) purple

B) red

C) colorless

D) brown

Answer:  A

Section:  3.3

Blooms Taxonomy:  Application

ASMcue Outcome:  8.1

Learning Outcome:  3.9

27) 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?

A) purple

B) red

C) colorless

D) brown

Answer:  C

Section:  3.3

Blooms Taxonomy:  Application

ASMcue Outcome:  8.1

Learning Outcome:  3.9

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

A) purple

B) red

C) colorless

D) brown

Answer:  A

Section:  3.3

Blooms Taxonomy:  Application

ASMcue Outcome:  8.1

Learning Outcome:  3.9

29) Which type of stain is most useful in helping clinicians to decide which antibiotic to prescribe for a bacterial infection?

A) negative stain

B) simple stain

C) Gram stain

D) endospore stain

E) flagella stain

Answer:  C

Section:  3.3

Blooms Taxonomy:  Analysis

ASMcue Outcome:  2.1

Learning Outcome:  3.10

Global Outcome:  2

30) Which of the following pairs is mismatched?

A) confocal microscope produces a three-dimensional image

B) darkfield microscope uses visible light

C) fluorescence microscope uses a fluorescent light

D) scanning electron microscope produces a three-dimensional image

E) scanning tunneling microscope allows visualization of atoms

Answer:  C

Section:  3.2

Blooms Taxonomy:  Analysis

ASMcue Outcome:  2.1

Learning Outcome:  3.4

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

A) 4.5x

B) 10x

C) 45x

D) 100x

E) 450x

Answer:  E

Section:  3.2

Blooms Taxonomy:  Application

ASMcue Outcome:  2.1

Learning Outcome:  3.3

32) You are studying a cell structure that is approximately 100 nm in size. Which of the following provides the greatest magnification you can use to see this structure?

A) brightfield microscope

B) darkfield microscope

C) transmission electron microscope

D) phase-contrast microscope

E) scanning electron microscope

Answer:  E

Section:  3.2

Blooms Taxonomy:  Analysis

ASMcue Outcome:  2.1

Learning Outcome:  3.6

Global Outcome:  2

33) Which microscope uses two beams of light to produce a three-dimensional color image?

A) fluorescence microscope

B) phase-contrast microscope

C) darkfield microscope

D) DIC microscope

E) electron microscope

Answer:  D

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.4

34) Which microscope is used to see intracellular detail in a living cell?

A) fluorescence microscope

B) two-photon microscope

C) atomic force microscope

D) transmission electron microscope

E) brightfield microscope

Answer:  B

Section:  3.2

Blooms Taxonomy:  Application

ASMcue Outcome:  2.1

Learning Outcome:  3.4

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

A) transmission electron microscope

B) darkfield microscope

C) fluorescence microscope

D) brightfield microscope

E) scanning electron microscope

Answer:  A

Section:  3.2

Blooms Taxonomy:  Application

ASMcue Outcome:  2.1

Learning Outcome:  3.6

36) Which microscope is used to see detail of a 300-nm virus?

A) fluorescence microscope

B) phase-contrast microscope

C) darkfield microscope

D) DIC microscope

E) electron microscope

Answer:  E

Section:  3.2

Blooms Taxonomy:  Application

ASMcue Outcome:  2.1

Learning Outcome:  3.6

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

A) cell walls.

B) capsules.

C) endospores.

D) flagella.

E) The answer cannot be determined.

Answer:  C

Section:  3.3

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  2.1

Learning Outcome:  3.11

38) Which step in the Gram stain is the critical step in differentiating gram-positive cells from gram-negative cells?

A) safranin

B) alcohol-acetone

C) iodine

D) crystal violet

Answer:  B

Section:  3.3

Blooms Taxonomy:  Analysis

ASMcue Outcome:  8.1

Learning Outcome:  3.9

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

A) an acid-fast stain

B) a flagella stain

C) a capsule stain

D) an endospore stain

E) a simple stain

Answer:  D

Section:  3.3

Blooms Taxonomy:  Analysis

ASMcue Outcome:  8.1

Learning Outcome:  3.9

40) Which microscope is best used for observing the surfaces of intact cells and viruses?

A) phase-contrast microscope

B) darkfield microscope

C) fluorescence microscope

D) brightfield microscope

E) scanning electron microscope

Answer:  E

Section:  3.2

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  2.1

Learning Outcome:  3.6

41) Bacterial smears are fixed before staining to

A) affix the cells to the slide.

B) make their walls permeable.

C) accept stain.

D) make the cells visible.

Answer:  A

Section:  3.3

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  8.1

Learning Outcome:  3.8

42) The resolution of a microscope can be improved by changing the

A) condenser.

B) fine adjustment.

C) wavelength of light.

D) diaphragm.

E) coarse adjustment.

Answer:  C

Section:  3.2

Blooms Taxonomy:  Application

ASMcue Outcome:  2.1

Learning Outcome:  3.3

43) 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

A) smaller than it would if immersion oil was used.

B) larger than it would if immersion oil was used.

C) somewhat fuzzy and have poor resolution.

D) the same as it would if the immersion oil was used.

E) to have no color.

Answer:  C

Section:  3.2

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  8.1

Learning Outcome:  3.3

44) The purpose of the ocular lens is to

A) improve resolution.

B) magnify the image from the objective lens.

C) decrease the refractive index.

D) increase the light.

E) decrease the light.

Answer:  B

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.3

45) In microscopy, the term resolution

A) refers to the ability to distinguish fine structure and detail in a specimen.

B) is the same as the total magnification of a specimen.

C) is improved when longer wavelengths of light are employed.

D) is only observed in stained specimens.

E) refers to magnification when using the electron microscope.

Answer:  A

Section:  3.3

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.3

3.2   True/False Questions

1) The counterstain used in the Gram stain is a basic dye.

Answer:  TRUE

Section:  3.3

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  8.1

Learning Outcome:  3.7

2) In a completed Gram stain, gram-negative bacteria are colorless.

Answer:  FALSE

Section:  3.3

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  8.1

Learning Outcome:  3.9

3) In a completed Gram stain, gram-positive bacteria are purple.

Answer:  TRUE

Section:  3.3

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  8.1

Learning Outcome:  3.9

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

Answer:  FALSE

Section:  3.2

Blooms Taxonomy:  Application

ASMcue Outcome:  2.1

Learning Outcome:  3.10

5) The limit of resolution of the compound microscope illuminated with visible light is approximately 0.2 m.

Answer:  TRUE

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.3

6) Both phase-contrast microscopy and differential interference contrast microscopy are used to

view the internal structures of cells without staining.

Answer:  TRUE

Section:  3.2

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  2.1

Learning Outcome:  3.4

7) Cells viewed in darkfield microscopy appear similar to those stained with the negative stain.

Answer:  TRUE

Section:  3.3

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  2.1

Learning Outcome:  3.4

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

Answer:  FALSE

Section:  3.3

Blooms Taxonomy:  Comprehension

ASMcue Outcome:  2.1

Learning Outcome:  3.11

9) 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.

Answer:  FALSE

Section:  3.2

Blooms Taxonomy:  Knowledge

ASMcue Outcome:  2.1

Learning Outcome:  3.6

10) Scanned probe microscopy is used to examine fine detail of molecular complexes, such as blood clots, or molecules, such as DNA.

Answer:  TRUE

Section:  3.2

Blooms Taxonomy:  Application

ASMcue Outcome:  2.1

Learning Outcome:  3.6

3.3   Essay Questions

1) In 1877, Robert Koch thought preparing permanently stained slides would be valuable. Why

was his assessment correct?

Section:  3.3

Blooms Taxonomy:  Synthesis

ASMcue Outcome:  2.1

Learning Outcome:  3.8

Global Outcome:  2

2) In 1884, Hans Christian Gram described a method of staining bacterial cells while not staining surrounding animal tissues. However, he thought that the staining method he developed was faulty because not all bacteria stained. In a letter to the editor of the journal in which Gram published his findings, write your response to Grams concern.

Section:  3.3

Blooms Taxonomy:  Evaluation

ASMcue Outcome:  2.1

Learning Outcome:  3.10

Global Outcome:  2

3) 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.

Section:  3.2

Blooms Taxonomy:  Application

ASMcue Outcome:  2.1

Learning Outcome:  3.4

Global Outcome:  2

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