2.5.3 osmosis

Question 1

osmosis

Answer 1

passage of water molecules down their water potential gradient across a partially permeable membrane

Question 2

water potential

Answer 2

measure of tendency of water molecules to diffuse from one region to another

Question 3

solution

Answer 3

liquid in which the solute molecules are dissolved in the solvent

Question 4

can water pass through phospholipid bilayer

Answer 4

yes

Question 5

aquaporins

Answer 5

allow water molecules to pass through membrane more rapidly

Question 6

lower conc of solute molecules

Answer 6

water potential higher

Question 7

higher conc of solute molecules

Answer 7

lower water potential = water molecules diffuse into solution

Question 8

water potential of pure water

Answer 8

highest possible = 0

Question 9

units for measuring water potential

Answer 9

kilopascals (kPa)

Question 10

water potential lowers

Answer 10

more negative

Question 11

cytolysis

Answer 11

in animal cells when a lot of water molecules enter & cell swells then bursts as plasma membrane breaks

Question 12

turgid

Answer 12

• in plant cells, rigid & strong cellulose wall prevents bursting
• cell will swell to certain size when contents push against cell wall & resists further swelling

Question 13

cremated

Answer 13

• cells placed in solution with lower water potential = water molecules leave cell by osmosis
• animal cell shrivels

Question 14

plasmolysed

Answer 14

cytoplasm of plant cell shrinks & membrane pulls away from cellulose cell wall

Question 15

flaccid

Answer 15

plant tissue with plasmolysed cells

Question 16

effect of plasmolysed cells on metabolism

Answer 16

metabolism cannot proceed as enzyme-catalysed reactions must be in solution