Movement Of Substances Into And Out Of Cells Flashcards
Diffusion
Passive
High to low conc
Until equilibrium
Osmosis
Selective process Water High to low conc Across partially permeable membrane Dilute and conc
Active transport
Energy Transport proteins Low to high conc Selective High number of mitochondria
Why does diffusion occur
Gas, liquid molecules are always moving
Random, bump into each other
If molecules are concentrated in one area, constant movement will evenly distribute them
Osmosis in plants in pure water
Cell, dilute Pure water, conc Water=>cell Cell swells Cytoplasm pushes against cell wall Turgid
Osmosis in conc sugar solution
Cell, dilute Sugar, conc Water<=cell Cell decreases in volume Cytoplasm does not push against cell wall Flaccid
Osmosis in really conc sugar solution
Contents of cell shrink
Membrane pulls away from cell wall
Plasmolysed
Space between cell wall and cell membrane, filled with sugar solution
Why do plants want to be turgid
Turgor pushes cells against each other, supports plant
Plant kept upright for photosynthesis
Stomata stay open, allow gas exchange for photosynthesis
Osmosis in animal cells
Do not have cell walls
Cannot resist internal pressures
Swell and burst, lysis
In conc solution, shrivel and have crinkled edges
Water potential
Used to describe how free water molecules are to move
0, pure water
- number, water dissolved with other stuff
High to low water potential
Factors that affect rate of movement of substances in and out of cell
SA:V
Temp
Conc gradient
Distance
Experiments to investigate diffusion
Potassium manganate crystals diffuse through water
Or through agar jelly
Potassium manganate will go clear in hydrochloride acid
Experiments to investigate osmosis
Cut 6 potato tissue cubes Record mass Put each one in test tube with different conc of sugar solution Find percentage change \+, water has entered cell
