Chapter 3 Practice ?

1. What is the function of the diaphragm on a compound microscope?
a) Controls the amount of light entering the condenser
b) Adjusts the focus of the objective lenses
c) Magnifies the specimen
d) Increases the magnification of the ocular lens

2. The ocular lens is used to…
a) Magnify the specimen directly
b) Magnify the image formed by the objective lens
c) Control the amount of light passing through the specimen
d) Adjust the resolution of the microscope

3. The measure of the light-bending ability of a medium is the:
a) Refractive index
b) Magnification
c) Resolution
d) Focal length

4. Most ocular lenses magnify specimens by a factor of:
a) 2x
b) 5x
c) 10x
d) 50x

5. The ability of the lenses of a microscope to distinguish fine detail and structure is called:
a) Magnification
b) Resolution
c) Contrast
d) Refraction

6. Which microscope uses an opaque disk to block light that would enter the objective lens directly?
a) Compound microscope
b) Darkfield microscope
c) Fluorescence microscope
d) Phase-contrast microscope

7. Which microscope uses an ultraviolet light source?
a) Scanning electron microscope
b) Phase-contrast microscope
c) Fluorescence microscope
d) Transmission electron microscope

8. Which microscope forms an image from two sets of light rays, one from the light source and the other diffracted from a structure in the specimen?
a) Compound microscope
b) Darkfield microscope
c) Fluorescence microscope
d) Phase-contrast microscope

9. What microscope uses a metal-and-diamond probe to produce a three-dimensional image?
a) Scanning electron microscope
b) Atomic force microscope
c) Transmission electron microscope
d) Phase-contrast microscope

10. Which microscope is especially useful in studying the surface structures of intact cells and viruses?
a) Scanning electron microscope
b) Fluorescence microscope
c) Transmission electron microscope
d) Darkfield microscope

11. In transmission electron microscopy, the specimen is placed on a:
a) Glass slide
b) Copper mesh grid
c) Petri dish
d) Plastic holder

12. Which microscope is extremely valuable for examining different layers of specimens and often involves the use of shadow casting?
a) Scanning electron microscope
b) Transmission electron microscope
c) Phase-contrast microscope
d) Atomic force microscope

13. With a scanning electron microscope, objects are generally magnified:
a) 10,000 to 100,000x
b) 1,000 to 500,000x
c) 50,000 to 1,000,000x
d) 100,000 to 10,000,000x

14. With a transmission electron microscope, objects are generally magnified:
a) 100 to 1,000x
b) 1,000 to 10,000x
c) 10,000 to 10,000,000x
d) 500,000 to 1,000,000x

15. Before microorganisms are stained, MOST appear ________ when viewed with brightfield microscopy.
a) Transparent
b) Colorful
c) Colorless
d) Green

16. The chromophore of basic dyes is a ________ and is ________ to MOST types of bacteria.
a) Anion; repelled
b) Cation; attracted
c) Cation; repelled
d) Anion; attracted

17. Which one of the following is NOT a kind of staining technique?
a) Gram stain
b) Negative stain
c) Selective stain
d) Acid-fast stain

18. The process of fixing a slide attaches the microorganisms while simultaneously:
a) Staining the bacteria
b) Killing the organisms
c) Enhancing the resolution
d) Magnifying the specimen

19. A technique used for preparing a slide with colorless bacteria against a colored background is called:
a) Simple staining
b) Negative staining
c) Gram staining
d) Differential staining

20. What is the mordant in the Gram stain?
a) Crystal violet
b) Iodine
c) Alcohol
d) Safranin

21. Flagella are stained with:
a) Crystal violet
b) Carbolfuchsin
c) Methylene blue
d) Carbolfuchsin

22. Capsules are stained using a(n):
a) Simple stain
b) Negative stain
c) Gram stain
d) Acid-fast stain

23. Endospores are stained using a(n):
a) Simple stain
b) Schaeffer-Fulton stain
c) Gram stain
d) Acid-fast stain

24. What color are gram-negative bacteria at the completion of the Gram staining process?
a) Purple
b) Pink
c) Blue
d) Red

25. The appearance of Mycobacterium leprae after they are stained with an acid-fast stain is:
a) Purple
b) Pink
c) Blue
d) Red

26. The primary purpose of the Gram stain is to:
a) Differentiate bacteria based on cell wall structure
b) Determine the presence of a capsule
c) Differentiate between live and dead bacteria
d) Identify bacterial flagella

Answer Key:

1. a) Controls the amount of light entering the condenser

2. b) Magnify the image formed by the objective lens

3. a) Refractive index

4. c) 10x

5. b) Resolution

6. b) Darkfield microscope

7. c) Fluorescence microscope

8. d) Phase-contrast microscope

9. b) Atomic force microscope

10. a) Scanning electron microscope

11. b) Copper mesh grid

12. b) Transmission electron microscope

13. b) 1,000 to 500,000x

14. c) 10,000 to 10,000,000x

15. c) Colorless

16. b) Cation; attracted

17. c) Selective stain

18. b) Killing the organisms

19. b) Negative staining

20. b) Iodine

21. b) Carbolfuchsin

22. b) Negative stain

23. b) Schaeffer-Fulton stain

24. b) Pink

25. b) Pink

26. a) Differentiate bacteria based on cell wall structure