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Biology 155 Lab > Exam 2 > Flashcards

Exam 2 Flashcards

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1
Q

Most bacteria have a rigid cell wall containing ________ that is responsible for maintaining the bacterial shape under a variety of osmotic conditions.

a. Ribonucleic Acid
b. Peptidoglycan
c. Anions
d. Aniline

A

b. Peptidoglycan

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2
Q

True or False:

The stains used on February 27 bind to the cell components because the stain is negatively charged

A

False

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3
Q

How long do you flood the slide with crystal violet?

a. 30 seconds
b. 10 minutes
c. 5 seconds
d. 1 minute

A

d. 1 minute

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4
Q

What is the purpose for adding the 95% alcohol to the slide?

a. To fix the stain
b. To stain gram negative cells
c. To decolorize (remove crystal violet from) the Gram-negative cells
d. There is no reason for this; it is just an extra step

A

c. to decolorize (remove crystal violet from) the Gram-negative cells

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5
Q

True or False:

The Gram stain is considered a simple stain.

A

False

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6
Q

True or False:
February 27th you worked with a mixed broth culture containing Escherichia coli, Staphylococcus epidermidis, and Serratia marcescens.

A

True

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7
Q

True or False:

Our microbiota is an important mechanism for limiting pathogenic microorganisms on our bodies.

A

True

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8
Q

The purpose of Streaking for isolation is to

a. Obtain isolated colonies
b. Make a mixed culture
c. Get a layer of growing cells covering the full surface of the plate medium
d. None of the above

A

a. Obtain isolated colonies

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9
Q

True or False:

One of the objectives in the lab on February 27 was to culture and study the microbiota of the human mouth

A

True

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10
Q

Our “blank” used for the spectrophotometer on March 6th was:

a. Water
b. Sterile medium
c. Undiluted broth culture
d. Clean empty spectrophotometer tube

A

b. Sterile medium

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11
Q

True or False:

When making serial dilutions there is no need to used accurate volume measurements

A

False

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12
Q

You have three plated from a serial dilution that were incubated. Plate A has 356 colonies, plate B has 6 colonies, and plate C has 128 colonies. Which plate(s) do you use to find the viable cell count?

a. Plate A
b. Plate B
c. Plate C
d. Plates A & B

A

c. Plate C

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13
Q

What temperature does the agar solidify at?

a. 100 degrees Celsius
b. 45 degrees Celsius
c. 15 degrees Celsius
d. 0 degrees Celsius

A

b. 45 degrees Celsius

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14
Q

CFU stands for…

a. Common Fungal Units.
b. Colony Forming Units.
c. Coliform Feeding Units
d. Campibacter Forming Units

A

b. Colony Forming Units

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15
Q

True or False:

Another term for Optical Density is Absorption.

A

True

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16
Q

Serial Quantitative Dilution

a. Mixing equal portions of microbial culture broth and water at once
b. Counting the microbes found in a agar plate
c. Counting the number of CFUs with fluorescing antigens
d. Diluting a culture sample into smaller and smaller concentrations, until you can count the number of CFUs.

A

d. Diluting a culture sample into smaller and smaller concentrations, until you can count the number of CFUs.

17
Q

An objective of lab on March 6th was to:

a. Calculate the number of live bacteria from the original, undiluted broth culture.
b. Calculate the number of dead cells in the original, undiluted broth culture
c. Determine how much water is used in order to get a 0 O.D. reading in the spectrophotometer
d. To determine the ratio of live cells compared to dead cells in the media

A

a. Calculate the number of live bacteria from the original, undiluted broth culture.

18
Q

An Autoclave is used

a. As a timer
b. To routinely sterilize medium and biohazardous garbage
c. To count the number of colonies growing on a medium
d. As an incubator

A

b. To routinely sterilize medium and biohazardous garbage

19
Q

What temperature will the steam reach in the Autoclave?

a. 121-123 degrees Celsius
b. 98-100 degrees Celsius
c. 250-275 degrees Celsius
d. 150-155 degrees Celsius

A

a. 121-123 degrees Celsius

20
Q

True or False:

The word ‘sterile’ means that no living organisms are present.

A

True

21
Q

On March 20th when we were transferring bacteria from the original broth culture to the sterile TSB tubes, we had to transfer:

a. No more than a single loop full
b. Two loops full
c. 3 microliters via micropipette
d. Just enough, by pouring, to make the TSB turbid

A

b. two loops full

22
Q

To test whether the autoclaving was successful in sterilizing material, we place an envelope of _____ in with a load that is being autoclaved.

a. Bacillus stearothermophilus endospores
b. Bacillus stearothermophilus vegetative (growing) cells
c. Bacillus stearothermophilus toxins
d. A plate of very concentrated Bacillus stearothermophilus cells

A

a. Bacillus stearothermophilus endospores

23
Q

True or False:

The autoclave allows us to use higher temperatures for sterilization through the use of pressure.

A

True

24
Q

True or False:

Dry heat penetrates more efficiently than moist heat.

A

False

25
Q

True or False:

Only glassware can be autoclaved.

A

False

26
Q

In lab on March 20th we worked with:

a. Egg Whites
b. Bacillus subtilis
c. An oven set at 100°C
d. All of the above

A

d. All of the above

27
Q

Heat kills microorganisms by _____.

a. Coagulating the cells’ proteins
b. Dehydrating the cells
c. Lysing the cells’ membranes
d. Causing DNA to mutate beyond repair

A

a. Coagulating the cells’ proteins

28
Q

True or False:

Mannitol Salt Agar (MSA) is selective for Staphylococcus and will inhibit growth of many gram-negative organisms

A

True

29
Q

Coliforms

a. Are Gram-negative
b. Are Facultative anaerobic rod-shaped bacteria
c. Will appear as deep purple colonies on a VRB media
d. All of the above

A

d. All of the above

30
Q

True or False:

A chemical used on a living object, such as tissue of a human body, for disinfection is called a disinfectant.

A

False

31
Q

True or False:

Violet Red Bile agar (VRB) is only a differential media.

A

False

32
Q

True or False:

Most resident microorganisms on our skin are Gram-negative bacteria and yeast.

A

False

33
Q

Which of these medias will you be using in lab today?

a. BAP, Blood Agar Plate
b. TSA, Tryptic Soy Agar
c. PCA, Plate Count Agar
d. None of the above

A

c. PCA, Plate Count Agar

34
Q

True or False:

When scrubbing your hands in the hand-washing experiment, your hands must be in the water.

A

True

35
Q

True or False:

Escherichia coli forms endospores.

A

False

36
Q

Transient organisms

a. Are part of the normal flora
b. Grow on our skin
c. Are pathogenic
d. Can survive for some time on our bodies

A

d. Can survive for some time on our bodies

37
Q

True or False:

Disinfection will destroy all bacteria the chemical comes in contact with.

A

False

Biology 155 Lab (2 decks)

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