Chapter 3 Study Guide

Microscopy and Staining Techniques CH3 SG

1. How many nanometers is 10 μm?
a) 1,000 nm
b) 10,000 nm
c) 100 nm
d) 1 nm

2. Through what lenses does light pass in a compound microscope?
a) Only through the ocular lens
b) Objective lens and ocular lens
c) Only through the objective lens
d) Condenser lens and ocular lens

3. What does it mean when a microscope has a resolution of 0.2 nm?
a) It can distinguish two points that are 0.2 nm apart.
b) It can magnify objects by 0.2 nm.
c) It can resolve two objects that are 0.2 mm apart.
d) It has a low resolution, meaning poor image clarity.

4. How are brightfield, darkfield, phase-contrast, and fluorescence microscopy similar?
a) They all require the use of ultraviolet light.
b) They all use visible light to view specimens.
c) They all use electron beams for magnification.
d) They all produce three-dimensional images.

5. Why do electron microscopes have greater resolution than light microscopes?
a) They use shorter wavelengths than light microscopes.
b) They use visible light to form images.
c) They are more focused on the objective lens.
d) They magnify objects using colored dyes.

6. For what is a Transmission Electron Microscope (TEM) used?
a) To observe live cells in real-time
b) To examine the surface of specimens
c) To study thin sections of organisms
d) To measure the size of viruses

7. For what is a Scanning Electron Microscope (SEM) used?
a) To examine internal structures of cells
b) To view the surface of whole microorganisms
c) To study molecules and atoms
d) To magnify biological molecules

8. For what is Scanned-Probe Microscopy used?
a) To visualize large cells
b) To produce three-dimensional images of surfaces
c) To measure the chemical composition of cells
d) To identify bacterial species

9. Why doesn’t a negative stain color a cell?
a) The stain only colors the background, not the cells.
b) The stain is not effective on certain types of cells.
c) The cells absorb the stain but appear colorless.
d) The stain requires a mordant to bind to the cell.

10. Why is fixing necessary for most staining procedures?
a) It helps to make cells more visible.
b) It kills and attaches microorganisms to the slide.
c) It colors the cells without the need for stains.
d) It prevents distortion during staining.

11. Why is the Gram stain so useful?
a) It identifies viral pathogens.
b) It differentiates bacteria based on their cell wall composition.
c) It stains bacterial nuclei.
d) It provides detailed internal views of bacterial cells.

12. Which stain would be used to identify microbes in the genera Mycobacterium and Nocardia?
a) Gram stain
b) Acid-fast stain
c) Endospore stain
d) Simple stain

13. How do unstained endospores appear?
a) Clear, colorless, and indistinct
b) Dark and opaque
c) Brightly colored
d) Transparent with a defined shape

14. How do stained endospores appear?
a) Bright red
b) Pink with a clear boundary
c) Green or blue
d) Dark purple

15. The most common microscope used in microbiology is the:
a) Fluorescence microscope
b) Transmission electron microscope
c) Compound light microscope
d) Scanning electron microscope

16. The total magnification of an object is calculated by:
a) Dividing the ocular lens magnification by the objective lens magnification
b) Adding the magnification of the objective lens and ocular lens
c) Multiplying the magnification of the objective lens by the ocular lens
d) Multiplying the magnification of the objective lens by the condenser lens

17. The compound light microscope uses:
a) A beam of electrons for imaging
b) A magnetic field for focus
c) Visible light for magnification
d) Infrared light for imaging

18. The maximum resolution (or resolving power) of a compound light microscope is:
a) 0.1 nm
b) 0.2 μm
c) 1.0 μm
d) 0.5 mm

19. The maximum magnification of a compound light microscope is:
a) 100x
b) 500x
c) 1,500x
d) 10,000x

20. Specimens are stained to:
a) Make them visible under a microscope
b) Alter the specimen’s size
c) Reduce the amount of light required for viewing
d) Prevent the specimen from deteriorating

21. Immersion oil is used with the oil immersion lens to:
a) Increase the contrast of the specimen
b) Magnify the specimen by 1,000x
c) Reduce light loss between the slide and the lens
d) Improve color resolution in the specimen

22. Brightfield illumination is used for:
a) Viewing live cells
b) Viewing unstained specimens
c) Viewing stained smears
d) Viewing bacterial flagella

23. Unstained cells are more productively observed using which type of microscopy?
a) Brightfield microscopy
b) Darkfield, phase-contrast, or DIC microscopy
c) Simple staining
d) Gram staining

24. The darkfield microscope shows:
a) Detailed internal structures of cells
b) A light silhouette of an organism against a dark background
c) Bacterial flagella in motion
d) Fluorescent stains illuminating cell walls

25. A phase-contrast microscope allows for:
a) Viewing three-dimensional structures
b) Detailed observation of living organisms without staining
c) Color differentiation between cell structures
d) Viewing surfaces of microorganisms in 3D

26. In fluorescence microscopy, specimens are first stained with:
a) Basic dyes
b) Fluorochromes
c) Carbolfuchsin
d) Methylene blue

27. Fluorescence microscopy is primarily used in:
a) Diagnosing viral infections
b) Studying microbial metabolism
c) The fluorescent-antibody (FA) technique
d) Viewing live bacteria

28. Instead of light, a beam of ________ is used with an electron microscope.
a) X-rays
b) Electrons
c) Laser beams
d) Ultraviolet light

29. Instead of glass lenses, electron microscopes use ________ to control focus, illumination, and magnification.
a) Electric fields
b) Electromagnets
c) Mirrors
d) Optical lenses

30. Thin sections of organisms can be seen in an electron micrograph produced using a:
a) Scanning electron microscope (SEM)
b) Compound light microscope
c) Transmission electron microscope (TEM)
d) Fluorescence microscope

31. Three-dimensional views of the surfaces of microorganisms can be obtained with:
a) TEM
b) Scanning electron microscope (SEM)
c) Scanned-probe microscope
d) Brightfield microscope

32. A smear is:
a) A thin film of material used for microscopic examination
b) A thick preparation of cells for easier staining
c) A specimen that has been cultured on agar
d) A method of collecting specimens

33. A mordant may be used in a staining procedure to:
a) Color the specimen
b) Kill microorganisms
c) Improve bonding between the stain and the specimen
d) Increase the size of the specimen

34. Differential stains, such as the Gram stain, are used to:
a) Identify bacteria based on their color
b) Differentiate bacteria according to their reactions to stains
c) Increase the magnification of specimens
d) Color specific structures inside bacterial cells

35. The Gram stain uses which of the following as a mordant?
a) Iodine
b) Crystal violet
c) Safranin
d) Alcohol

36. Gram-positive bacteria remain ________ after the decolorization step of the Gram stain.
a) Pink
b) Blue
c) Purple
d) Colorless

37. Which of the following bacteria appears red after an acid-fast stain?
a) Mycobacterium tuberculosis
b) Escherichia coli
c) Staphylococcus aureus
d) Bacillus anthracis

38. A negative stain is used to make ________ visible.
a) Endospores
b) Microbial capsules
c) Flagella
d) Bacterial cell walls

39. Endospore staining is used to visualize:
a) Flagella
b) Capsules
c) Endospores
d) Cell membranes

40. Flagella staining is used to visualize:
a) Microbial capsules
b) Flagella
c) Endospores
d) Fimbriae

41. Which of the following is a characteristic of electron microscopes?
a) Use visible light
b) Have a magnification limit of 1,500x
c) Use electromagnets instead of glass lenses
d) Can only examine living specimens

Answer Key:

1. b) 10,000 nm

2. b) Objective lens and ocular lens

3. a) It can distinguish two points that are 0.2 nm apart.

4. b) They all use visible light to view specimens.

5. a) They use shorter wavelengths than light microscopes.

6. c) To study thin sections of organisms

7. b) To view the surface of whole microorganisms

8. b) To produce three-dimensional images of surfaces

9. a) The stain only colors the background, not the cells.

10. b) It kills and attaches microorganisms to the slide.

11. b) It differentiates bacteria based on their cell wall composition.

12. b) Acid-fast stain

13. a) Clear, colorless, and indistinct

14. c) Green or blue

15. c) Compound light microscope

16. c) Multiplying the magnification of the objective lens by the ocular lens

17. c) Visible light for magnification

18. b) 0.2 μm

19. c) 1,500x

20. a) Make them visible under a microscope

21. c) Reduce light loss between the slide and the lens

22. c)Viewing stained smears
    23. b) Darkfield, phase-contrast, or DIC microscopy
    24. b) A light silhouette of an organism against a dark background
    25. b) Detailed observation of living organisms without staining
    26. b) Fluorochromes
    27. c) The fluorescent-antibody (FA) technique
    28. b) Electrons
    29. b) Electromagnets
    30. c) Transmission electron microscope (TEM)
    31. b) Scanning electron microscope (SEM)
    32. a) A thin film of material used for microscopic examination
    33. c) Improve bonding between the stain and the specimen
    34. b) Differentiate bacteria according to their reactions to stains
    35. a) Iodine
    36. c) Purple
    37. a) Mycobacterium tuberculosis
    38. b) Microbial capsules
    39. c) Endospores
    40. b) Flagella
    41. c) Use electromagnets instead of glass lenses