2.9: the effect of pH on microbial growth

Question 1

pH= -log (-6)=

Answer 1

-6

Question 2

The pH range is from:

Answer 2

-0 to 14

Question 3

Acidophiles:

Answer 3

-grow well below pH of 5.5

Question 4

Neutrophiles:

Answer 4

-grow well in pH of 5.5 and 8.5

Question 5

Alkaliphiles:

Answer 5

-live above ph of 8.5

Question 6

Under natural circumstances, the majority of bacteria maintain a ?? internal environment regardless of their habitat because they have ?? buffers

Answer 6

-near-neutral
-cytoplasmic

Question 7

changes to pH outside an organisms range may destroy necessary ?? potential and damage vital ?? beyond repair

Answer 7

-membrane
-enzymes

Question 8

Describe the procedure:

Answer 8

-3 different cultures where put into different broth tubes of a Ph of 3, 7, or 10
-incubate test tubes for 35+2C for 48 hours

Question 9

In the pH scale, 7 is

Answer 9

-neutral

Question 10

Buffers are added to bacterial growth media to prevent

Answer 10

-pH changes that would denature cellular proteins

Question 11

If an organism grows best at a pH of 9.5, it is described as:

Answer 11

-alkaliphile

Question 12

A solution with a pH of 3 is _________ _________ than a solution with a pH of 6.

Answer 12

-more acidic

Question 13

Pure water has a pH of

Answer 13

-7

Question 14

TRUE OR FALSE:
Changes to pH outside an organism’s range may destroy necessary membrane potential and damage vital enzymes beyond repair.

Answer 14

-true

Question 15

TRUE OR FALSE:
-Buffers made of weak acids are typically added to bacteriological growth media.

Answer 15

-true

Question 16

TRUE OR FALSE:
Changes in pH might result in denatured enzymes

Answer 16

-true

Question 17

TRUE OR FALSE:
The conventional means of expressing the concentration (or activity) of hydrogen ions in a solution is pH.

Answer 17

-true

Question 18

results:
clear broth=
turbity broth=

Answer 18

-no growth
-growth