Microbiology Lab Midterm
A quiz to help prep for Microbio midterm on Tues. :(
- 1.
What is the definition of Total Magnification?
- A.
The clearance distance between the front of the object and the uppersurface of the coverglass
- B.
The ability to discriminate between two discrete objects seperated by a minute distance
- C.
Abiility of detail to stand out against the background or other adjacent details
- D.
Individual magnifying power of the objective multiplied by that of the eyepiece
Correct Answer
D. Individual magnifying power of the objective multiplied by that of the eyepiece -
- 2.
What is the formula for the Numerical aperature (N.A.)?
- A.
N.A. = 1/n*sin(alpha)
- B.
N.A. = n*sin(alpha)
- C.
N.A. = n* sing (1/alpha)
- D.
N.A.=1/n*sin (1/alpha)
Correct Answer
B. N.A. = n*sin(alpha) -
- 3.
Define Resolving Power.
- A.
The ability to discriminate between two discrete objects seperated by a minute distance
- B.
Individual magnifying power of the objective multiplied by that of the eyepiece
- C.
Abiility of detail to stand out against the background or other adjacent details
- D.
The clearance distance between the front of the object and the uppersurface of the coverglass
Correct Answer
A. The ability to discriminate between two discrete objects seperated by a minute distance -
- 4.
Which N.A. would have a brighter image and higher resolution? N.A.= 1.25 or N.A. = 0.1?
- A.
N.A. = 1.25
- B.
N.A. =0.1
Correct Answer
A. N.A. = 1.25Explanation
The larger the N.A., the brighter the image and higher the resolution. This is why oil immersion (100x) has a N.A. of 1.25 while 4x objective has a N.A. of 0.1 typically.Rate this question:
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- 5.
Label all the parts of the Microscope.
Correct Answer
i) Ocular (eyepiece) ii) course & fine focus iii) condenser focusing knob v) objectives vi) stage vii) N/A viii) light source - 6.
What on the microscope is used to move the objectives?
Correct Answer
TURET - 7.
Define Contrast.
Correct Answer
Contrast = the ability of a detail to stand out against the background or other adjacent details - 8.
TRUE OR FALSE.The shorter the working distance, the lower the magnifying power.
- A.
FALSE
- B.
TRUE
Correct Answer
A. FALSEExplanation
The shorter the workding distance, the higher the magnifying power of the objective. (E.g.) 100 x is shorter while 4x is longerRate this question:
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- 9.
What is the purpose of the CAD (condenser aperature diaphragm) lever?
- A.
Centers the light through the specimen
- B.
Controls the width of the light beam
- C.
Controls the angle of the light beam
- D.
Centers the specimen under the light beam
Correct Answer
C. Controls the angle of the light beam -
- 10.
What is the purpose of the Field Diaphragm lever?
- A.
Centers the light through the specimen
- B.
Controls the width of the light beam
- C.
Controls the angle of the light beam
- D.
Centers the specimen under the light beam
Correct Answer
B. Controls the width of the light beam -
- 11.
What is the purpose of the Condenser Focusing Knob?
- A.
Centers the light through the specimen
- B.
Controls the width of the light beam
- C.
Controls the angle of the light beam
- D.
Centers the specimen under the light beam
Correct Answer
A. Centers the light through the specimen -
- 12.
What is the purpose of Koehler Illumination?
- A.
Increase contrast, decrease resolution, & achieve even illumination
- B.
Increase contrast, decrease resolution, & achieve uneven illumination
- C.
Decrease contrast, decrease resolution, & achieve even illumination
- D.
Decrase contrast, decrease resolution, & achieve uneven illumination
- E.
Increase contrast, increase resolution, & achieve even illumination
Correct Answer
E. Increase contrast, increase resolution, & achieve even illumination -
- 13.
List the steps of Koehler Illumination.
Correct Answer
1. While viewing thru the microscope, close the field diaphrams lever to the right. 2. focus the edges of the heptagon with the condenser focusing knob. 3. center the image with the condenser centering screws. Open the field diaphragm lever til the leaves are just beyond the field of view 4. close the condenser diaphram (to left) til you find a balance between contrast and resolution. - 14.
Why do we use Immersion Oil instead of no oil when viewing specimens under a microscope?
Correct Answer
When light moves from air to glass, they have different refractive indexes which causes the light to bend. Thus, less light hits the specimen and you get a less clear image. With Immersion oil, its refractive index is the same as glass, making the light go straight through and yield higher resolution and contrast of the specimen. - 15.
Name and describe the 3 states of media & give an example of each
- 16.
The definition of subculture is?
- A.
Transfer microbes from one media to another, ASEPTICALLY (i.e. without contamination)
- B.
Isolation of organisms for identification
- C.
Isolation of organism for counting
Correct Answer
A. Transfer microbes from one media to another, ASEPTICALLY (i.e. without contamination) -
- 17.
Explain the different purposes between a spread plate and a streak plate.
- 18.
What shapes do spores have? Where are spores located on the cell?
- A.
Shape: spherical, circular, cylindrical; location: central, subcentral, terminal
- B.
Shape: spherical, ellipsoidal, cylindrical; location: central, terminal, subterminal
- C.
Shape: spherical, ellipsoidal, subellipsoidal; location: central, terminal, suterminal
Correct Answer
B. Shape: spherical, ellipsoidal, cylindrical; location: central, terminal, subterminal -
- 19.
1. If you had 8 plates and 30 mL of water was needed per plate, how much water total is needed?2. This is equivalent to how many Liters?
- A.
24 mL, 2.4 L
- B.
240 mL, 24 L
- C.
.24 mL, .240 L
- D.
240 mL, .24 L
Correct Answer
D. 240 mL, .24 LExplanation
8 plates* (30mL/plate) = 240 mL
240 ml* (1000 mL/L) = 0.24 LRate this question:
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- 20.
Now that you have calculated that 240 mL of water is needed for 8 plates. 30 grams of powdered TSB/L of water equals _______ grams of TSB powder required.
- 21.
Describe the Morphological shapes of organisms.
- 22.
Which of the following is NOT a type of microscope?
- A.
Brightfield, fluroescent, TEM, SEM
- B.
Phase contrast, phase contract, darkfield
- C.
SEM, darkfield, brightfield, TEM
Correct Answer
B. Phase contrast, phase contract, darkfield -
- 23.
Which of the following types of microscopes does NOT have a resolving power of 0.2 micrometeres?
- A.
Brightfield
- B.
Darkfield
- C.
Fluorescent
- D.
TEM
Correct Answer
D. TEMExplanation
TEM has 2 nm while SEM is 3 nmRate this question:
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- 24.
What is the difference between Brightfield and Darkfield?
- 25.
Name the types of Electron microscopes and the differences between them.
- 26.
Define parfocal.
- 27.
Describe at least 3 factors that affect gram staining and its effects.
- 28.
TRUE OR FALSE?Defined means to know the exact amount while undefined is any animal, peptone or plant in which you don't know the exact amount.
- A.
True.
- B.
False.
Correct Answer
A. True. -
- 29.
Name the 3 parts to every stain.
- 30.
What makes up a "Chromagen"?
Correct Answer
benzene + chromophore = chromagen - 31.
What are the two types of simple stains?
Correct Answer
Basic staining: (+) charge binds to (-) such as cell wall. Appears dark against a light backgroun. Acidic stains: (-) charge, repels away from cell wall. Organism appears light while to the background is dark. - 32.
What are the 2 types of staining? Briefly describe each.
- 33.
What does "Mordant" mean?
- A.
INCREASES the cell's affinity for something else.
- B.
DECREASES the cell's affinity for something else.
Correct Answer
A. INCREASES the cell's affinity for something else. -
- 34.
What is the MOST critical step in a Gram stain?
- A.
Crystal violet
- B.
Gram's Iodine
- C.
95% ethanol
- D.
Safranin
Correct Answer
C. 95% ethanol -
- 35.
Put the Gram Stain in the correct order.
- A.
1. 95% ethanol 2. safranin 3. crystal violet 4. Gram's Iodine
- B.
1. Gram's Iodine 2. 95% ethanol 3. safranin 4. crystal violet
- C.
1. safranin 2. gram's iodine 3. 95 % ethanol 4. crystal violet
- D.
1. crystal violet 2. gram's iodine 3. 95 % ethanol 4. safranin
Correct Answer
D. 1. crystal violet 2. gram's iodine 3. 95 % ethanol 4. safranin -
- 36.
List and describe each step of the Gram Stain. How/why does this work?
- 37.
Overdecolorizing with ethanol will result in?
- A.
No change
- B.
G(+) is altered
Correct Answer
B. G(+) is altered -
- 38.
Underdecolorizing with ethanol in a Gram stain results in?
- A.
No change.
- B.
G(-) still purple.
Correct Answer
B. G(-) still purple. -
- 39.
When one single cell or culture appears to be both G(+) and G(-) and you cannot change their Gram reaction...this is referred to as?
- A.
Gram variability
- B.
Gram invariability
- C.
Gram negativity
- D.
Gram susceptibility
Correct Answer
A. Gram variabilityExplanation
Example of Gram variability: B.cereusRate this question:
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- 40.
Define colony morphology.
- 41.
What are the 2 ways to observe colony characteristics?
- 42.
Name the 2 types of media and describe each.
- 43.
Fill in the missing steps in Biochemical testing:1. Name of the test2.3.4.5. +/- results. What looks like and what it means.
Correct Answer
2. medium required and any special ingredients 3. function of test and reaction 4. reagents added AFTER incubation - 44.
Why must reagents in biochemical testing be added AFTER incubation?
- 45.
Which of the following statments is FALSE about capsules?
- A.
Formed when times are bad
- B.
Non-ionic
- C.
Can be used as a food source
- D.
Protection against immune system
Correct Answer
A. Formed when times are badExplanation
Caosules are formed when times are GOOD because lots of nutrients help it form; main focus of survivalRate this question:
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- 46.
Which of the following statements about SPORES are FALSE?
- A.
Hard to kill
- B.
Reproductive
- C.
Formed when times are good
Correct Answer(s)
B. Reproductive
C. Formed when times are goodExplanation
Spores are NOT reproductive nor do they form when times are good like capsules.
Spores are the reason we heat the autoclave to 121 C.Rate this question:
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- 47.
Why are spores hard to kill?
- A.
Water resistant
- B.
Resistant to heat
- C.
Resistant to drying
Correct Answer(s)
B. Resistant to heat
C. Resistant to drying -
- 48.
What does it mean to say that a capsule is "non-ionic"?
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Mar 20, 2022Quiz Edited by
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Oct 19, 2008Quiz Created by
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