Lab Exam 2

Question 1

The Durham tube inverted in a tube of Phenol Red Broth detects the production of which of the following?

Answer 1

gas

Question 2

Catalase converts which of the following chemicals to oxygen and water?

Answer 2

hydrogen peroxide

Question 3

Yellow and no bubble in the Durham tube is an indication of

Answer 3

A/-
acid

Question 4

The color of phenol red at an acid pH is?

Answer 4

yellow

Question 5

A growth medium that favors the growth of some microorganisms but inhibits the growth of other microorganisms is a ________________ medium.

Answer 5

selective

Question 6

solid media

Answer 6

-2% agar
- can see colony morphology, pigmentation, hemolysis
-examples are Nutrient Agar and Trypticase Soy Agar

Question 7

liquid media

Answer 7

-no agar
-for inoculum preparation
-Examples are nutrient broth, trypticase soy broth

Question 8

semi-solid medium

Answer 8

.5% agar
motility medium

Question 9

special purpose media

Answer 9

aids in the isolation and identification of specific microorganisms

Question 10

selective media

Answer 10

inhibit the growth of one organism and permits the growth of another
-helpful when separating a mixture of gram-positive and gram-negative

Question 11

differential media

Answer 11

cause an observable color change when a particular chemical reaction occurs

Question 12

Phenylethyl Alcohol Agar (PEA)

Answer 12

selective media
allows the growth of gram-positive and inhibits the growth of gram-negative
used to isolate staph and strep

Question 13

MacConkey (MAC)

Answer 13

-selective and differential
-the selective ingredients are bile salts which inhibit gram positive
-differential ingredient is lactose

Question 14

If fermentation occurs on MAC agar, what color would the indicator be?

Answer 14

pink-red

Question 15

Mannitol Salt Agar

Answer 15

-selective and differential
-selects for staph
-differential ingredient is sugar mannitol
-7.5% NaCl

Question 16

If fermentation occurs on Mannitol Salt Agar, what color is the indicator?

Answer 16

yellow

Question 17

Phenol red pH indicator

Answer 17

yellow for acid and fuchsia pink for basic
differential
uses glucose, sucrose, and lactose

Question 18

Eosin Methylene Blue

Answer 18

differential and selective medium
the differential indicator dyes are eosin Y and methylene blue

Question 19

If fermentation occurs on EMB agar, what color is it?

Answer 19

large amounts of acid are green and small amounts are pink

Question 20

What two gram negative bacterias grow on EMB?

Answer 20

E coli and pseudomonas aeruginosa (no lactose)

Question 21

Citrate test

Answer 21

detect the ability of certain bacteria to utilize citrate as the sole source of carbon
-the indicator is bromothymol blue

Question 22

If citrate is used, what color does the indicator turn if alkali is used)

Answer 22

blue

Question 23

If citrate and acid is used, what color does the indicator turn?

Answer 23

yellow

Question 24

What color indicates citrate negative?

Answer 24

green

Question 25

Fermentation tubes

Answer 25

ability to ferment a specific sugar is dependent on enzymes and F tube use phenol red detect gas production

Question 26

Starch test

Answer 26

differential iodine is the indicator

Question 27

fermentation

Answer 27

the incomplete break down of substrates

Question 28

In phenol red, what does red broth and no bubble indicate?

Answer 28

no fermentation, no acid -/-

Question 29

In phenol red, what does yellow broth with a bubble?

Answer 29

A/G acid and gas production

Question 30

In Simmons Citrate Agar, what does green agar indicate?

Answer 30

- citrate is not utilized

Question 31

In Simmons Citrate Agar, what does blue agar indicate?

Answer 31

+ citrate is utilized

Question 32

In Triple Sugar Iron, what does an alkaline slant and acid butt indicate?

Answer 32

K/A bacteria ferments glucose

Question 33

In TSI, what does an acid slant, acid butt, and gas production indicate?

Answer 33

A/A, G bacteria ferments glucose, sucrose, lactose and making acid

Question 34

In TSI, what does an alkaline slant, acid butt, and H2S production?

Answer 34

K/A, H2S bacteria ferments glucose and makes acid hydrogen sulfide is also formed