microbiology lab practical 2

Question 1

Standard autoclave procedure

Answer 1

121 degrees C, 15 pounds of pressure, 15 minutes

Question 2

Standard incubation procedure

Answer 2

37 degress C, 48 hours

Question 3

Streak plate: purpose

Answer 3

To get isolated colonies to work with.

Question 4

Streak plate: Where do the bacteria come from?

Answer 4

a patient specimen

Question 5

Inoculation plate: purpose

Answer 5

To get a pure culture.

Question 6

Incoculation plate: Where do the bacteria come from?

Answer 6

the streak plate

Question 7

Gram stain: function and result of

Step 1: crystal violet

Answer 7

Function: stain all the bacteria purple

Result: G+: purple G-: purple

Question 8

Gram stain: function and result of

Step 2: iodine

Answer 8

Function: fix the crystal violet even stronger to

the G+ bacteria.

Result: G+: purple G-: purple

Question 9

Gram stain: function and result of

Step 3: ethyl alcohol

Answer 9

Function: wash the crystal violet out of the

G- bacteria.

Result: G+: purple G-: clear

Question 10

Gram stain: function and result of

Step 4: safranin

Answer 10

Function: stain the G- bacteria pink

Result: G+: purple G-: pink

Question 11

chains ( stained blue

Answer 11

Kingdom: Monera Where found: dirt/dust

Clinical significance: lung infection or a blood

infection with a compromised immune system.

Scientific name: Bacillus subtilis

Question 12

pink globs

Answer 12

Kingdom: Monera Where found: the intestine of animals

Clinical significance: UTI, diarrhea, blood infections

Scientific name: E. coli

Question 13

blueberries

Answer 13

Kingdom: Monera Where found: on skin

Clinical significance: UTI in females

Scientific name: Staphylococcus saprophyticus

Question 14

What microbes predominate in milk early on–

when we first buy the milk?

Answer 14

Streptococcus and Lactobacillus

Question 15

What microbes predominate in milk later on–

when the milk has gone really bad?

Answer 15

Pseudomonas and yeast

Question 16

What microbe is mainly responsible for

making milk go sour?

Answer 16

Lactobacillus

Question 17

What two genus of bacteria are found on the surface

of most raw chicken at the store?

Answer 17

Salmonella and Campylobacter

Question 18

Gram stain result: Corynebacterium xerosis

Answer 18

G+ rod, individual cells, no endspores

Question 19

Gram stain result: Lactobacillus

Answer 19

G+ rod, in chains, no endospores

Question 20

Gram stain result: Pseudomonas, Salmonella,

Campylobacter

Answer 20

They are all a G- rod, individual cells.

Question 21

Independent variable

Answer 21

The variable whose effect is being measured.

Question 22

Dependent variable

Answer 22

The variable that might be affected by

the independenet variable.

Question 23

Control Group, Experimental Group

Answer 23

These two groups receive the exact same living

conditions, except the control group does not

receive the independent variable and the

experimental group does receive the

independent variable.

Question 24

Sample hypothesis: Ingesting saccharin will cause an

increase in bladder cancer rates among lab rats.

Identify: independent variable, dependent variable,

control group, experimental group

Answer 24

Independent variable: ingesting saccharin

Dependent variable: bladder cancer rates

Control group: a group of lab rats that receive

no saccharin in their diet.

Experimental group: an equal number of lab

rats that receive saccharin in their diet

every day.

Question 25

Sample hypothesis: the use of smokeless tobacco will

cause an increase in oral cancer rates.

Identify: independent variable, dependent variable,

control group, experimental group

Answer 25

Independent variable: using smokeless tobacco

Dependent variable: oral cancer rates

Control group: a group of people who do not use

smokeless tobacco

Experimental group: an equal number of people

who do use smokeless tobacco

Question 26

Phenol: how used/antiseptic

Answer 26

It is put into some throat lozenges:

Antiseptic: Yes

Question 27

Hexachlorophene: how used, antiseptic

Answer 27

It is added to some types of soap and detergent.

Antiseptic: yes

Question 28

Cresol: how used, antiseptic

Answer 28

It is the active ingredient of Lysol.

Antiseptic: no

Question 29

Alcohol: how used, antiseptic

Answer 29

The active ingredient of Scope and Listerine.

Also used on skin (rubbing alcohol).

Antiseptic: yes

Question 30

Chlorine: how used, antiseptic

Answer 30

The active ingredient of Bleach.

Also used in much smaller doses in

swimming pools and drinking water.

Antiseptic: the high dose used in

Bleach:  no       the much smaller

dose used in swimming pools and

drinking water: yes

Question 31

Iodine: how used, antiseptic

Answer 31

Kills bacteria excellent on the skin.

Antiseptic: yes

Question 32

Hydrogen peroxide: how used, antiseptic

Answer 32

Used on cuts sometimes.

Antiseptic: yes

Question 33

Results: Bacteria put in to a 20% NaCl solution:

E. coli 50 colonies

Staphylococcus epidermidis 300 colonies

Conclusion?

Answer 33

The results are expected.

Question 34

Results: Bacteria put into a 20% NaCl solution.

E. coli 300 colonies

Staphylococcus epidermidis 50 colonies

Conclusion?

Answer 34

The results are not expected.

Question 35

Results: Bacteria boiled for 15 minutes:

E. coli 0 colonies

Bacillus subtilis 80 colonies

Conclusion?

Answer 35

The results are expected.

Question 36

Results: Bacteria boiled for 15 minutes

E. coli 80 colonies

Bacillus subtilis 0 colonies

Conclusion?

Answer 36

The results are not expected.

Question 37

Results: flaming bacteria/endospores for 1 second:

Growth

Conclusion?

Answer 37

The results are expected.

Question 38

Results: flaming bacteria/endospores for 1 second.

No growth

Conclusion?

Answer 38

The results are not expected.

Question 39

Results: flaming bacteria/endospores for 5 seconds:

Growth

Conclusion?

Answer 39

The results are not expected.

Question 40

Results: flaming bacteria/endospores for 5 seconds.

No growth

Conclusion?

Answer 40

The results are expected.