Microbiology Lab midterm review-1,26,3,4,5,7,11,20

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1

Fixing of bacteria to a slide is done by passing the bacterial smear over the flame of a Bunsen burner BUT it can also be chemically done using

methanol

2

What type of information below cannot be determined by a simple stain?
a. thick/thinness of a cell wall
b. cell arrangement
c. morphology
d. size

thick/thinness of cell wall

3

True or false. When making a smear from solid media you must mix your bacteria in a small amount of water first.

true

4

What is the name of the mordant in Gram-staining called?

Gram's iodine

5

Gram negative cells will show the color of the ____ stain after gram staining

safranin

6

What is the name of the apparatus you use in class to sterilize your inoculating tools?

Bunsen burner

7

There are 2 dilution techniques. Which technique does not allow you to quantify?
a. pour plate
b. streak plate
c. spread plate

streak plate

8

__________ is the most common isolation technique.

streak plate technique

9

After Gram-staining cells appear pink. What does this tell you about the bacterial cells?

the cells have a thin wall

10

The ideal age that a bacterial culture should be used for staining is?

18-24 hours

11

In the spread plate method colonies grow on and in the agar or only on the surface?

only on the surface

12

Turbidity can be used using a machine called a ______________.

spectrophotometer

13

What happens to the % of transmittance as a microbial cell population in nutrient broth increases?

decreases

14

What happens to absorbance as a microbial cell population in nutrient broth increases?

increases

15

In determining bacterial level cells/ml you should choose an agar plate that contains between _________ colonies.

25-250

16

Generation time is the time required for a ___________?

cell to divide into 2 cells

17

In Gram staining the safranin is the __________.

basic stain

18

The shorter the generation time the ________ the growth.

faster

19

A chromophore is the _____________.

the ion that is colored

20

A pure culture is one that?

only contains a single kind of microbe

21

The iris diaphragm can be found _______ the __________.

below the condenser

22

In a Brightfield microscope

dark objects are viewed against a bright background

23

In a parfocal microscope where the specimen has been focused at low power will only need minor adjustment by using the __________ as you increase the magnification.

fine adjustment knob

24

If the total magnification of your specimen is 400x which objective lens was being used?

high dry lens

25

What happens to the field of vision as you change your objective lens from low power to the scanning lens?

it increases

26

Agar is a solidifying agent that is extracted from?

algae

27

Which of the following type of media is used to grow bacteria that require small amounts of oxygen?

agar deep

28

A bacterial organism was introduces into a tube of nutrient broth which has been allowed to sit at 30*C for 24 hours. After this time it is observed to have clumps of microbial cells suspended in the broth while the remainder appears cloudy. What bacterial growth pattern is this exhibiting?

flocculent

29

Which of the following is solid media?
a. nutrient broth
b. Agar slant
c. Agar deep

agar slant

30

Permanent bacteria that can reside and multiply are

normal microflora

31

unwanted microbe

contaminant

32

liquid media is?

nutrient broth

33

cloudy as a result of bacterial growth is?

turbidity

34

intentional introduction of microbes onto or into media

inoculate

35

steam sterilization under pressure

autoclaving

36

population of cells arising from a single bacterial cell

colony

37

to grow

culture

38

substance that turned red when metabolized by bacteria

tetrazolium chloride

39

bacteria that reside temporarily and cannot multiply

transient

40

What tool should be used to introduce microbes into an agar deep?

inoculating needle