1.3 Osmosis

Question 1

what is osmosis

Answer 1

the diffusion of water across a membrane

Question 2

define osmosis

Answer 2

The net movement of water molecules from a higher conc (of water) to a lower conc (of water), across a selectively permeable membrane, until equilibrium

Question 3

what is the general water potential(Ψ) rule

Answer 3

water always moves from a high to low water potential.

Question 4

What is the water potential(Ψ) of 100% pure water

Answer 4

Ψ = 0

(0 is the highest Ψ possible)

Question 5

as an estimate, give the Ψ(kPa) of:
1. pure water
2. dilute solution
3. concentrated solution

Answer 5

1. 0 kPa
2. -200 kPa
3. -500kPa

Question 6

define: isotonic solution

Answer 6

a solution of equal solute concentration to a cell

Question 7

define: hypertonic solution

Answer 7

a solution of higher solute concentration than a cell

Question 8

define: hypotonic solution

Answer 8

a solution of lower solute concentration than a cell

Question 9

effects of hypotonic solution on animal cell

Answer 9

• water enters
• cell swells and may lyse(burst)

Question 10

effects of hypotonic solution on plant cell

Answer 10

• water enters
• cell swells and becomes turgid

Question 11

effects of isotonic solution on animal cell

Answer 11

• no net movement of water
• cell normal size

Question 12

effects of isotonic solution on plant cell

Answer 12

• no net movement of water
• cell normal size

Question 13

effects of hypertonic solution on animal cell

Answer 13

• water leaves
• cell shrinks and CRENATES

Question 14

what is it called when a cell shrinks in an ANIMAL CELL

Answer 14

crenation

Question 15

effects of hypertonic solution on plant cell

Answer 15

• water leaves
• cytoplasm shrinks and PLASMOLYSES
  (therefore flaccid)

Question 16

what is it called when a PLANT CELL membrane shrinks away from its cell wall

Answer 16

Plasmolysis.

Question 17

how do protoctistans such as amoeba which live surrounded by a HYPOTONIC solution prevent swelling or lyse?

Answer 17

expel water using contractile vacuoles

Question 18

how do cells in marine environments which live surrounded by a HYPERTONIC solution reduce water potential?

Answer 18

actively pump ions into cells

Question 19

how do non-woody plants keep cells hypertonic to the cell to allow osmosis

Answer 19

actively pump ions into cells

Question 20

how is water potential of the cell calculated

Answer 20

Ψcell = Ψs +Ψp

Question 21

what does Ψs stand for

Answer 21

solute potentual
(always -ve)

Question 22

what does Ψp stand for

Answer 22

pressurre potential
(always +ve)

Question 23

which has the highest water potential:
1. -400
2. -380
3. -360

Answer 23

3

Question 24

which has the lowest water potential:
1. -400
2. -380
3. -360

Answer 24

1