Tonicity and Osmoregulation 2.8

Question 1

What does it mean if a solution is hypotonic?

Answer 1

More solvent and less solute(ions)

Question 2

What does it mean if a solution is hypertonic?

Answer 2

More solute(ions) and less solvent.

Question 3

What does it mean if a solution is isotonic?

Answer 3

Equal concentrations of solvent and solute

Question 4

If inside of the cell is hypotonic and outside of the cell is hypertonic, what direction would the water flow in? What is the result of the cell?

Answer 4

It would flow out of the cell because it would balance the water to ion ratios. This causes plasmolysis (shrinking of the plant cell).

Question 5

If inside of the cell is isotonic and outside of the cell is isotonic, what direction would the water flow in? What is the result of the cell?

Answer 5

It would be at dynamic equilibrium with water flowing in and out at equal rates. (no net movement). This plant cell is flaccid.

Question 6

If inside of the cell is hypertonic and outside of the cell is hypotonic, what direction would the water flow in? What is the result of the cell?

Answer 6

The water would into the cell so that the excess ions in the cell would have enough water to balance it. This would be a turgid plant cell (full).

Question 7

What is water potential? How does it explain the direction of water movement?

Answer 7

It measures the tendency of water to move by osmosis.

Water Potential= Pressure Potential+Solute potential

Water moves from high water potential to low water potential.

Negative means water will move into that area while positive means water is likely to leave that area.

Question 8

Calculate the water potential of 0.0MPa ΨP and -0.2MPa Ψs . Which direction would the water flow? Justify.

Answer 8

-0.2 water potential with water flowing into the cell.

Question 9

Calculate the water potential of 0.8MPa ΨP and -0.4MPa Ψs . Which direction would the water flow? Justify.

Answer 9

0.4 water potential with water flowing out of the cell

Question 10

What is homeostasis?

Answer 10

The tendency towards a relatively stable equilibrium point.

Question 11

What is osmoregulation?

Answer 11

Organisms have the ability to control their internal solute concentration and water potential

Question 12

Identify two ways that the cell complete osmoregulation.

Answer 12

By allowing water to diffuse into a cell that in hypertonic to its environment. or visa versa

Question 13

Identify two ways that organisms complete osmoregulation.

Answer 13

a

Question 14

Which direction would water flow if one solution A is 0.5 M and solution B is 0.2 M?

Answer 14

It would flow to B as it has the lower water potential.

Question 15

Which direction would water flow if one solution A is 0.3 M and solution B is 0.6 M?

Answer 15

It would flow to A as it has the lower water potential.

Question 16

Calculate the solute potential of sucrose with a concentration of 0.5M at 25 Celcius. What direction will the water flow if water pressure is equal to zero?

Solute Potential= -iCRT
R=0.0831
sucrose i=1
NaCl=2
K= C+273
C-molar concentration

Answer 16

=-(.5)(0.0831)(25+273)
=-12.382

The water will flow into the cell since it has a negative water potential.

Question 17

Calculate the solute potential of NaCl with a concentration of 0.3M at 27 Celcius. What direction will the water flow if water pressure is equal to zero?

Solute Potential= -iCRT
R=0.0831
sucrose i=1
NaCl=2
K= C+273
C-molar concentration

Answer 17

=(-2)(0.3)(0.0831)(27+273)
=14.958

The water will flow out of the cell since it has a positive water potential.

Question 18

Osmosis

Answer 18

diffusion of free water across a selectively permeable membrane

Question 19

solute

Answer 19

substance being dissolved

Question 20

Terms for plant cell osmosis states

Answer 20

Turgid, flaccid, and plasmolyzed

Question 21

terms for animal cell osmosis states

Answer 21

lysed, normal, shriveled

Question 22

What does an increase in the amount of solute casue?

Answer 22

More solute means greater solute potential (meaning it is more negative) and less water potential based on the equation Water potential=solute potential + pressure potential.