microbiology lab exam 1 part 1

While viewing a specimen under a microscope, a drop of oil must be used with which of the following lenses?

Group of answer choices

100X

10X

40X

4X

100x

While observing a specimen, you should always start with higher magnification and then switch to lower magnification.

Group of answer choices

True

False

false

Calculate the total magnification that will be obtained when you view a specimen under a microscope using 40X objective lens.

Group of answer choices

400X

40X

1000X

100X

40 × 10 (eye piece is 10x) = 400

Oil is used with the oil immersion objective to reduce loss of light due to refraction.

Group of answer choices

True

False

true

---------------- focuses the light from the bulb onto the specimen.

Group of answer choices

Condensor

Occular Lens

Objective Lens

Fine Adjustment Knob

condensor

1.     List in steps, how you would transfer bacteria from a liquid culture to a plate.  You have access to all the equipment discussed in the protocol for aseptic techniques. 

 

1.     Ensure proper PPE is on

2.     Disinfect bench, wash hands, and put on new gloves

3.     Light Bunsen burner

4.     Light the loop until red and allow it to cool

5.     Uncap the culture tube without setting the cap on the table

6.     Put the tube opening on the flame

7.     Put loop inside the tube to get bacteria

8.     Put the tube top on the flame and recap

9.     Take off the agar lid and use the loop to place bacteria onto the surface

10.  Close the plate

11.  Flame the loop again

You have accidentally spilled some bacterial culture on the lab floor.  Name two reagents that you can use to clean the spill.

 Bleach (10%) and or Ethanol (70%)

1.     During an experiment, a beaker containing ethanol is accidentally set on fire.   Describe how you will put out the ethanol fire.

Use an fire blanket or fire extinguisher—could also use lid to remove the oxygen.

While incubating plates for bacterial growth, the plates should be kept inverted.  This is because

Group of answer choices

Plates are not stable if placed in an upright position

Oxygen will diffuse properly if plates are placed in an inverted position

plates will accumulate condensation on surface, if they are not inverted

It is easier to identify inverted plates because the labeled side faces up.

plates will accumulate condensation on surface, if they are not inverted

A bacterial colony represents

Group of answer choices

an empty petridish

progeny of a single cell

one single bacterial cell

a region on a plate where there is no growth

progeny of a single cell

The three domains of life include

Group of answer choices

Algae, Fungi and Protozoa

Viruses, Eukarya and Mitochondria

Viruses, Bacteria and Eukarya

Archaea, Bacteria and Eukarya

Archaea, Bacteria and Eukarya

Viruses are capable of independent growth while bacteria are not capable of independent growth on plates.

Group of answer choices

True

False

false

Viruses can form colonies on a nutrient agar plate.

 

Group of answer choices

True

False

false

Surface A supports the growth of bacteria

Surface A shows more growth of organisms than B

Surface B shows more growth of organisms than A

Surface A supports the growth of viruses

Surface A supports the growth of bacteria

Surface B shows more growth of organisms than A

A bacterial cell lacks a nucleus and other organelles.

Group of answer choices

True

False

true

Bacterial will continue to grow if nutrients in the bacterial environment are depleted.

Group of answer choices

True

False

false

Ubiquity of microbes refers to their ability to

Group of answer choices

metabolize different nutrients

assume different shapes

tolerate acidic conditions

grow everywhere

grows everywhere

The purpose of the streak plate method is to obtain isolated colonies on an agar plate.

Group of answer choices

True

False

true

While performing a quadrant streak, the purpose of sterilizing the loop between each quadrant is:

Group of answer choices

to reduce the number of bacteria in each quadrant

to prevent contamination of plate

to prevent contamination of the bacterial sample from which the plate was generated.

to make sure that bacteria will not be killed.

to reduce the number of bacteria in each quadrant

A bacterial colony is formed from a single bacterial cell

Group of answer choices

True

False

true

What was the purpose of picking samples from the quadrant 4?

individual, well isolated colonies in quadrant 4 will generate a pure culture

individual, well isolated colonies in quadrant 4 will generate a mixed culture

different bacteria are present in quadrants 4 and 1

quadrant 4 looks prettier than 1

individual, well isolated colonies in quadrant 4 will generate a pure culture

After performing a quadrant streak, you would expect to find isolated colonies in the --------quadrant

Group of answer choices

fourth quadrant

first quadrant

second quadrant

third quadrant

4th

The following plate was streaked in what order starting from first to last?

1,2,3,4

4,3,2,1

2,1,3,4

4,1,2,3

1,2,3,4

Which of the following statement(s) are correct about a bacterial colony?

Group of answer choices

Members are produced by repeated binary fissions

Members are genetically alike

Members are product of a single cell

All of the above are correct

All of the above are correct

bacterial colony

Which of the following conclusions can be definitely made about the sample used to streak the plate shown below? Select all of the correct answers for full credit.

The sample represents a mixed culture

The sample represents a pure culture

The sample contains bacteria

The sample contains viruses

The sample contains bacteria and is pure

Which of the following plates demonstrate Quadrant Streak method?

2

1

3

4

2

Colony morphology aids in identification of bacteria.

Group of answer choices

True

False

true

Based on the picture below, what can you definitely say about the original sample from which this plate was streaked?

The bacteria in the original sample are "heat loving"

The sample was obtained from soil

The sample contains different types of bacteria

The original sample contains ONLY bacteria.

The sample contains different types of bacteria

What definite conclusions can you make from the following picture? (FYI, all colonies shown in the picture are red in color).

The organisms shown here is a fungus

A pure culture is shown here.

The organism shown here was isolated from soil.

A mixed culture is shown here.

A pure culture is shown here.

Study of bacterial colony morphology gives the researcher information about shape of individual bacterial cells in the colony.

Group of answer choices

True

False

false

The colonies in the following picture can be described as:

Group of answer choices

circular, pigmented, mucoid, smooth

rhizoid, colorless, mucoid

filamentous, pigmented, dry

circular, lobate, mucoid, smooth

circular, pigmented, mucoid, smooth

The colonies shown in the picture have a  ---------- margin.

Group of answer choices

undulate

erose

lobate

smooth

smooth

The texture of the colony shown in the picture is best described as

 

Group of answer choices

Mucoid

Circular

Dry

Rhizoid

mucoid

The colony shown in the picture has a  ---------- margin.

 

 

Group of answer choices

smooth

punctiform

filamentous

lobate

lobate

Pigmentation (color) of the colony can aid in the identification of microorganisms.

Group of answer choices

True

False

true

Bacterial colonies can be described on the basis of:

1. Color and Opacity

2. Form and Margin

3. Elevation

4. Texture

5. Biochemical properties

1,2,3&5

1,2,3,4, & 5

4&5

1,2,3 & 4

1,2,3 & 4

The following image shows what type of cell?

Group of answer choices

Neither Gram negative nor Gram positive

Both Gram negative and Gram positive

Gram negative

Gram positive

gram negative

What can you conclude from the following picture of a gram stain?

 

Group of answer choices

Gram positive rods

Gram positive cocci

Gram negative, spiral shaped bacteria

Gram negative cocci

Gram negative, spiral shaped bacteria

Bacteria are differentiated into gram positive and gram negative cells based on differences in their   ---------------.

Group of answer choices

Nucleus

Cytoplasm

Cell Wall

Ribosomes

cell wall

Which of the following describes the correct order of reagents used in Gram Stain technique?

Group of answer choices

Crystal Violet, Iodine, Safranin and Decolorizer

Crystal Violet, Iodine, Decolorizer and Safranin

Safranin, Iodine, Decolorizer and Crystal Violet

Decolorizer, Crystal Violet, Iodine and Safranin

Crystal Violet, Iodine, Decolorizer and Safranin

---------------- cells have a thin layer of peptidoglycan, while --------------- cells have a thick layer of peptidoglycan in their cell walls.

Group of answer choices

Gram negative, Gram negative

Gram positive, Gram positive

Gram negative, Gram positive

Gram postive, Gram negative

Gram negative, Gram positive

What conclusions can you draw about the following picture?

 

Group of answer choices

Cells are rod shaped, gram negative and arranged in a chain

Cells are rod shaped, gram positive and arranged in a chain.

Cells are rod shaped, gram negative, and arranged as single cells.

Cells are spherical shaped, gram positive and arranged in a chain

Cells are rod shaped, gram positive and arranged in a chain.

Which of the following statements is correct?

A. Gram negative cell has a thick peptidoglycan layer which can bind Crystal Violet.

B. Gram negative cells stain pink with Safranin because, in the previous step, the decolorizer disrupts the outer membrane, causing leakage of Crystal Violet stain.

C. Crystal Violet stains the outer membrane purple in Gram negative cells, because of which they cannot take up Safranin.

D. The function of Iodine during Gram staining is to dissolve the peptidoglycan layer. 

Gram negative cells stain pink with Safranin because, in the previous step, the decolorizer disrupts the outer membrane, causing leakage of Crystal Violet stain. B

What can you definitively conclude about the picture below?

 

Group of answer choices

Pure culture is shown in the picture

All cells in the picture are rod shaped

Mixed culture is shown in the picture

All cells in the picture are gram postive

mixed culture

What can you conclude from the following picture of a gram stain?

 

Group of answer choices

Gram positive rods

Gram negative cocci

Mixed culture

Gram positive cocci

gram negative cocci

What can you conclude from the following picture of a gram stain?

 

Group of answer choices

Mixed culture is shown in the picture

Individual cells of gram negative bacteria

Gram positive bacteria growing in chains

Gram negative bacteria growing in chains

Gram positive bacteria growing in chains