module 2 - 5.5 osmosis

Question 1

how is a solution formed?

Answer 1

solute dissolved in a solvent (always water) to form a solution

Question 2

what is concentration?

Answer 2

amount of solute dissolved per unit volume of solvent

Question 3

what is water potential?

Answer 3

pressure exerted by water molecules as they hit a container or membrane

Question 4

what does water potential quantify?

Answer 4

quantifies the tendency of water to move from one area to another due to osmosis and hydrostatic pressure effects

Question 5

what does it mean to quantify something?

Answer 5

give it numbers

Question 6

what is hydrostatic pressure?

Answer 6

pressure of water

Question 7

what is osmosis?

Answer 7

specific type of diffusion

Question 8

why is osmosis a specific type of diffusion?

Answer 8

because it applies only to water molecules moving across a partially permeable membrane down a concentration gradient

Question 9

what is osmosis explained in terms of?

Answer 9

water potential

Question 10

what is the water potential of pure water?

Answer 10

0kPa

Question 11

why is osmosis diffusion?

Answer 11

because it is the solvent molecules moving within solute molecules

Question 12

how will the water move by osmosis?

Answer 12

from area of high WP to low WP through a partially permeable membrane until equilibrium has been reached

Question 13

what leads to a hydrostatic pressure?

Answer 13

movement of water into cells causing the cell volume to increase

Question 14

can animals increase/decrease in hydrostatic pressure?

Answer 14

no - they cannot increase nor decrease

Question 15

what does it mean if cell if a cell is hypertonic?

Answer 15

a solution with a higher WP compared to the cell (cells shrivel)
- causes cells to be crenelated

Question 16

what does it mean if a cell is isotonic?

Answer 16

a solution with the same WP as the cell (equal)
- causes equilibrium

Question 17

what does it mean if a cell is hypotonic?

Answer 17

a solution with a lower WP compared to the cell (cells burst)
- causes cytolysis

Question 18

why do cells go through cytolysis/ crenelation?

Answer 18

plasma membranes can’t stretch easily and have no mechanical strength to withstand hydrostatic pressure

Question 19

what are erythrocytes?

Answer 19

red blood cells

Question 20

which is more dense: red blood cells or plasma

Answer 20

plasma

Question 21

what happens when water enters a plant and increases the hydrostatic pressure?

Answer 21

the strong cellulose cell wall can withstand the pressure and the cell becomes turgid

Question 22

cells do not suffer from cytolysis, so what happens when they do not have enough water in them?

Answer 22

they become plasmolysed/ cell is hypertonic

Question 23

what happens to a cell when a cell has too much water in it?

Answer 23

cell becomes turgid/ cell is hypotonic

Question 24

what happens when water movement is in equilibrium in and out of a plant?

Answer 24

cell becomes flaccid/ cell is isotonic

Question 25

is there higher water potential in or out of cytoplasm in plants?

Answer 25

higher WP out of cytoplasm in plants

Question 26

what happens to plasma membrane when plant cell is flaccid/ isotonic?

Answer 26

plasma membrane ‘peels’ away from cell wall, contents no longer pushing against cell wall