Lab 16: Effect of Osmotic Pressure

Question 1

define osmosis

Answer 1

the movement of H2O across a semi-permeable membrane
- always from a area of low solute concentration to an area of high solute concentration

Question 2

define a halophile

Answer 2

organisms that are able to grow in NaCl concentrations greater than 3%

Question 3

define extreme halophiles

Answer 3

organisms that require at least a 13% concentration of NaCl to grow

Question 4

define facultative

Answer 4

organisms tolerating a wide range of solute concentrations

Question 5

define obligate

Answer 5

organisms tolerating a very narrow range of solute concentrations

Question 6

which organisms were halophiles?

Answer 6

S. epi and E. coli

Question 7

S. epi is termed a ________ organism

Answer 7

facultative

Question 8

which solution is more detrimental to bacterial cells?

Answer 8

hypertonic b/c plasmolysis occurs and metabolic enzymes are no longer active

Question 9

define plasmolysis

Answer 9

water moving out of a cell to equalize pressure causing the cell to shrink/ collapse

Question 10

list examples of food with high solute concentrations that inhibit the growth of bacteria

Answer 10

1. honey
2. dried meats
3. pickles
4. soy sauce
5. cinnamon