D2.3 Water Potential

Question 1

solute

Answer 1

a substance which dissolves in a solvent to make a solution

Question 2

why is water a good solvent?

Answer 2

dipolar
negative and positive
hydrogen side is slightly positive
the oxygen side is slightly negative

Question 3

solvation

Answer 3

interaction between a solvent, such as water, and a solute is known as solvation

Question 4

osmosis

Answer 4

the net movement of water molecules from a region of lower solute concentration to a region of higher solute concentration, through a partially permeable membrane

Question 5

cell membrane is partially permeable which means

Answer 5

allows small molecules (like water) through but not larger molecules (like solute molecules)

Question 6

what happens if a cell is placed in a solution with a lower solute concentration

Answer 6

there will be a net movement of water into the cell by osmosis

Question 7

hypotonic

Answer 7

A hypotonic solution is a solution that has a lower concentration of solute compared to the cell

net movement of water out of the cell

Question 8

how is a hydration shell formed

Answer 8

when water surrounds the solute

Question 9

hydrophilic

Answer 9

attracted to water and can dissolve in it eg. salt

Question 10

hydrophobic

Answer 10

not attracted to water
can’t dissolve in water
attracted to other hydrophobic molecules
eg oil

Question 11

hypertonic

Answer 11

the solution outside the cell has a higher solute concentration ( more concentrated) than the cytoplasm of the cell

a net movement of water out of the cell

Question 12

isotonic

Answer 12

the movement of water into the cell will be balanced out by the movement of water out of the cell

There will therefore be no net movement of water into or out of the cell
The cell is now in dynamic equilibrium with the isotonic solution

Question 13

standard error

Answer 13

an estimate of the reliability of the mean of a population sample

Question 14

crenated

Answer 14

happens to cells in hypertonic solutions when the net out flow of water is higher

can identify in a diagram as having ragged edges

Question 15

what extra part of freshwater unicellular animals have and why

Answer 15

since they are in danger of bursting because they’re always in water they have a contractile vacuole

Question 16

contractile vacuole

Answer 16

a small vesicle in the cytoplasm of many freshwater protists that expels excess water

Question 17

Effects of Osmosis on Cells Without Cell Walls

Answer 17

animal cells don’t have cell walls

results on the cell are more severe than on plant cells

hypertonic solution - crenated (shrivel)

hypotonic - no cell wall to create turgor pressure - burst eventually

Question 18

Effects of Osmosis on Cells With Cell Walls

Answer 18

As water enters the vacuole of the plant cell, the volume of the plant cell increases

The expanding protoplast pushes against the cell wall and pressure builds up inside the cell - turgor pressure

won’t burst because of cell wall

Question 19

turgid

Answer 19

When a plant cell is fully inflated with water and has become rigid and firm

Question 20

what happens when water leaves the vacuole

Answer 20

volume decreases and pulls away from cell wall
the plant cell becomes flaccid and is said to be plasmolysed

Question 21

Application of Isotonic Solutions in Medicine

Answer 21

intravenous (IV) drip to treat dehydration or to deliver medicine directly into the bloodstream