Water Potential D2.3

Question 1

What is solvation?

Answer 1

the reaction between solute and solvent molecules.

Question 2

What is the most important factor in determining how well solvents solvate a solute?

Answer 2

solvent polarity, polar solvents are good.

Question 3

How does water react with solutes as a solvent?

Answer 3

an ionic solute like NaCl will break into its ions in water since polar attractions cause water molecules to surround and isolate solute molecules.the partial charges of water interact with charges or partial charges of the solute.

Question 4

What is solute concentration?

Answer 4

the amount of solute (in moles) per unit volume (in dm^3). 1dm^3 = 1L

Question 5

What is an isotonic solution?

Answer 5

there is no difference in concentration of solute, = number of water molecules move between them

Question 6

What is a hypertonic solution?

Answer 6

higher concentration of solute in solution > cell, water molecules leave the cell and shrinks

Question 7

What is a hypotonic solution?

Answer 7

lower concentration of solute in solution > cell, water molecules enter the cell and expand

Question 8

What does it mean to be osmotically active solutes? Examples?

Answer 8

to be cause osmosis to occur (can induce the movement of water across a semipermeable membrane). IONS
- sodium
- potassium
- chloride

Question 9

What is the effect of water on animal cells?

Answer 9

animal cells bathed in a hypotonic solution will make cell swell and because it lacks the support of a cell wall, it will lyse/burst

Question 10

What is the effect of water on plant cells?

Answer 10

plant cells bathed in hypertonic solution will shrink and pull away from the cell wall which creates a decrease in pressure, reducing the volume of the cytoplasm.

Question 11

Applications of isotonic solutions?

Answer 11

• intravenous drips with normal saline solutions
• rinse wounds and skin abrasions
• keep areas of skin moistened prior to skin grafts
• contact solution
• eye drops
• nasal irrigation
• frozen to slush for donor organs during transportation

Question 12

What water has a water potential of 0?

Answer 12

pure water used at standard atmospheric pressure and 20C

Question 13

What is water potential?

Answer 13

the potential energy of water ler unit volume, relative to pure water. used to quantify the tendency of water to move from dilute to concentrated solutions due to osmosis.

Question 14

What is water potential denoted by?

Answer 14

the symbol Ψ (psi) and expressed in units of pressure (kilo pascal, kPa)

Question 15

What are factors that affect water potential?

Answer 15

• rises and falls in hydrostatic pressure (high pressure = more potential)
• solute concentration (when solutes dissolve the potential dec) (high concentration = less potential)

Question 16

How does water move?

Answer 16

moves from high concentration to low to minimize diff in potential energy

Question 17

What is the formula for water potential?

Answer 17

Ψ = ΨS + ΨP

Question 18

What does the number on ΨS mean?

Answer 18

negative = high solute concentration

Question 19

Water potential in hypotonic solutions of plant cells?

Answer 19

increased water potential

Question 20

Why is water potential increased in hypotonic solutions?

Answer 20

• water moves into the cell creating a increase in pressure on the cell wall (increase of ΨP)
• more water molecules than solute and therefore ΨS decreases

Question 21

Water potential in hypertonic solutions of plant cells?

Answer 21

decreased water potential

Question 22

Why is water potential decreased in hypertonic solutions?

Answer 22

• water moves out, fewer water molecules = decrease in pressure
• more solute than water molecules and increase of solute concentration