D2.3 Water Potential

Question 1

Water potential

Answer 1

The pressure exterted by water molecules when they collide with a container or.a membrane

Measured in kPa; Ψ (Psi)

Question 2

Solute Potential

Answer 2

The contribution solute makes to the water potential of a solution
* the greater the solute potential the lower the water potential

Because the more solute = the less water

Question 2

How water potential works

Answer 2

• pure water has the highest water potential at 0kPa (standard temp & pressure; 25 degrees, 100kPa)
• solutions have lower water potential than pure water = always negative

Question 2

Pressure Potential

Answer 2

The contribution pressure makes to the water potential of a solution
* the greater the pressure the greater the water potential

Question 3

Water Potential equation

Answer 3

ΨW = ΨS + ΨP

Question 4

Hypertonic

Answer 4

higher concentration then cells cytoplasm => water leaves cell

Question 5

Hypotonic

Answer 5

Lower concentration then cells cytoplasm => water enters cell

Question 6

Isotonic

Answer 6

Same concentration as cells cytoplasm
=> cell stays normal

Question 8

Plasmolysis

Answer 8

The shrinking of the cytoplasm away from the cell wall of a plant or bacteria

Question 9

Contractile Vacuole

Answer 9

Prevents cell lysis as it takes in water during osmoregulation

Question 10

Lysis

Answer 10

too much water flows into cell causing it to burst under turgor pressure

Question 11

What happens to the rate of osmosis if the water potential gradient is larger?

Answer 11

faster

Question 11

How is water absorbed from the spil into the roots

Answer 11

• active transport of ions from the soil into the root
• vauses low concentration in root = low water potential
• water flows inside root hair cell by osmosis

Question 12

Where in the plant would you expect negative pressure potential

Answer 12

in the xylem
= tension created in xylem due to transpiration stream and movement of water through continuous column

Question 13

Problem with overwatering

Answer 13

• soil saturation
• oxygen deprivation
• impact on Active transport

Question 14

What happens to plant cell in hypotonic solution

Answer 14

• hypotonic means high water potential outside
• water goes in plant cell by osmosis
• water absorbed by vacuole and it presses against plant cell wall = increased pressure
• cell wall prevents from bursting = remains turgid

Question 15

What does low solute potential infer

Answer 15

low water potential

(the more solute you add the more negative solute potential gets)

Question 16

medical applications of isontonic solutions

Answer 16

• to restore fluid balance in dehydrated patients
• used as a vehicle for drug delivery and avoids cellular damage or fluid shifts
• irrigation to clean wounds/ surgical sites
• management of electrolyte imbalances
• treatment of shock by maintaining blood pressure and volume