BIOL 351 Lab Exam 1 quizzes!

What will the concentration of your most dilute plate be in THIS protocol?

10-6

In order to have sterile agar for a Pour Plate, the agar must first be sterilized in an autoclave. This agar would be too hot and kill the cells. What temperature do you need to cool the agar to in order not to kill all of the cells?

50*C

Which of the following things below would result in a pure culture?

A completely isolated colony growing on a plate

What criteria must be met for a culture to be considered a pure culture?

A culture that contains a single bacterial species

What kind of microscope will you be using in this laboratory exercise?

A light microscope

How much water would you use on a slide when doing a bacterial smear procedure?

A very small amount

After which of the following steps in the Gram stain process could you detect a difference between Gram + and Gram- bacteria if you looked really hard?

After de-colorization with alcohol

How often should you sterilize your loop when doing a streak plate?

At the beginning, every time you change quadrants, and at the end

You will only add antibiotics to your Sabouraud media (SDA). All of the following explain why except one. Which one is NOT a reason you only want to add antibiotics to the SDA plate?

Because it would turn the GYE plates black and your results will be hard to see

When using the streak plate technique when is it necessary to sterilize your loop?

Between quadrants on your streak plate After you have completed the last quadrant

What is the appropriate time to flame your inoculating loop when transferring your culture

Both before and after you transfer the bacteria

Which of the following is not one of the major genera of antibiotic producing genera found in soil?

Clostridium

What does CFU stand for?

Colony forming units

Which of the following things is a safe practice when transferring cultures?

Hold the inoculating loop like a pencil

Under which circumstances would you choose a negative stain protocol over a Gram stain?

If the bacteria would lose their delicate shape or shrink when heat fixing

Where would you expect to find a saprophyte organism?

In soil

There is only ONE objective you should use when using lens immersion oil. The oil will damage all other objectives. According to figure 3.4, how would you identify the only lens in which you would use immersion oil?

It has a black and white ring around it

What is an ocular micrometer?

It is a ruler

When a cap is removed from a tube in the transfer process, where does that cap go?

It is held by the pinky finger of your loop hand

How do you determine a positive presumptive test?

It will be cloudy and have gas production

Which of the following characteristics would be FALSE for a coliform?

It would be a Gram+ organism

Which of the following is NOT a source of getting a poor/ inconsistent Gram stain?

Making sure to air dry the smear before heat fixing

What does MPN stand for?

Most Probable Number

Microorganims are ubiquitous. This means they would be found in which of the following places?

Soil The body On an aluminum railing

What would you use to clean lens immersion oil off of your objective lens before putting your microscope away?

Special lens paper

Some bacteria can lyse (break down) red blood cells in a process called hemolysis. Match the following descriptions of hemolysis with the correct outcome on a blood agar plate: β hemolysis

The blood agar plate will show clear around the bacterial growth due to complete hemolysis of the red blood cells

What could be a possible explanation for what went wrong on the streak plate below?

The loop was not sterilized between quadrants

Some bacteria can lyse (break down) red blood cells in a process called hemolysis. Match the following descriptions of hemolysis with the correct outcome on a blood agar plate: α hemolysis

There will be a greenish colored zone around the bacterial growth due to incomplete lysis of the red blood cells

Which of the following explanations is correct as to how a negative stain works?

They are negatively charged and therefore are repelled by the bacteria, and surround it so that it stands out.

Which of the following is the reason a simple stain will stick to a bacteria?

They are positively charged and the bacteria are negatively charged

Which of the following are not the purpose of streaking for individual colonies?

To decrease cell density To obtain isolated colonies To observe colony morphology

Though all of the following things are true, according to your lab manual,which of the things below is the MAIN reason you never set a test tube on the counter, but place it in a rack instead?

To prevent the test tube from leaking

In your epi-tubes you are transferring continually more dilute samples from tube to tube. According to your spread plate protocol, which of the following represents the order of tubes from most concentrated to most dilute?

Tube order: A,B,C,D

Which of the following is the correct location to label a tube and a plate?

Tubes are labeled on the glass and plates are labeled on the bottom

When counting cells on a Pour Plate, what do you do with the small colonies you can see embedded in the agar?

You add them to the total count

How much distance is between each line in an ocular micrometer?

You can't answer this unless you know the calibration for what magnification you are on

How would you calculate the total magnification of a microscope?

You multiply the magnification of the Ocular lens by the magnification of the Objective lens

The purpose of the streak plate method is to isolate individual colonies. Which of the following things is NOT true about the streak plate method?

Your most isolated colonies should appear in quadrant 1

Match the organism with the media that is specifically designed for it: Glycerol Yeast Extract Agar (GYE)

actinomycetes

transparent

almost invisible, or easy to see the light through

Match the organism with the media that is specifically designed for it: Nutrient Agar (You will substitute Triptic Soy Agar- TSA)

bacteria

The handles of inoculating loops can get very hot. How hot can your inoculating loop get if you leave it in the incinerator for a really long time?

close to 800*

Uniform fine turbitity

evenly cloudy throughout

Match the organism with the media that is specifically designed for it: Sabouraud Dextrose Agar (SDA)

fungi

ring

growth at the top around the edge

What results would you see for the following streak plate technique errors? Answers can be used more than once. Not drawing your loop through the previous quadrant

growth in quadrant 1

Sediment

growth on the bottom

pellicle

membrane at the top

What is the correct term for a chemical that helps to fix another chemical in place by complexing with it?

mordant

What results would you see for the following streak plate technique errors? Answers can be used more than once. Sterilizing your loop after obtaining a culture sample but before streaking your plate

no growth on plane

What results would you see for the following streak plate technique errors? Answers can be used more than once. Obtaining a culture sample before streaking every quadrant.

no single colonies, all four quadrants look the same

Prigment

produces colored growth

Which of the following morphology terms would describe a tiny pinpoint colony?

punctiform

friable

rough texture with crusty appearance

Filiform

smooth texture with solid edge

spreading edge

solid growth seeming to radiate outward

Flocculent

suspended chunks or pieces

Some bacteria can lyse (break down) red blood cells in a process called hemolysis. Match the following descriptions of hemolysis with the correct outcome on a blood agar plate: ϒ hemolysis

the blood agar plate will show no hemolysis

What results would you see for the following streak plate technique errors? Answers can be used more than once. Sterilizing the loop between each quadrant

this is not an error

Match the media type below with its intended purpose? Broths

used to grow cultures

Match the media type below with its intended purpose? Plates

used to isolate species

Match the media type below with its intended purpose? Agar slants

used when you want to grow a culture to store in the refrigerator