Diffusion And Osmosis Flashcards
What happens in diffusion
Molecules move around randomly- kinetic energy
When there is equal conc of molecules there is no net change
Diffusion
Molecules moving from an area of high conc to an area of low conc until an equilibrium is reached
How does the concentration gradient affect the rate of diffusion
The steeper the concentration gradient the faster the rate of diffusion
How does the diffusion distance affect the rate of diffusion
The shorter the diffusion distance the faster the rate of diffusion
How does the surface area affect the rate of diffusion
The greater the SA the faster the rate of diffusion
How does the temperature affect the rate of diffusion
The close the temp, the slower the rate of diffusion & vice versa as molecules have more/ less kinetic energy
What is SA/ V ratio
The amount of SA per unit of volume
What are cell membranes….
Selectively permeable
What happens in diffusion when there is a large SA
Lose heat
Get rid of CO2 fast
Take up useful molecules
What happens in diffusion with a small SA
Retain heat well
What are the disadvantages of bigger organisms
The amount of SA it has per unit of volume gets smaller
Diffusion takes longer
The SA is too small for their volume
Osmosis
The movement of water molecules from an area of high water conc to an area of low water conc across a
Selectively permeable membrane
Solute concentration in cells
High water conc outside the cell diffuses into the cell
Cytoplasm
Water, salts, organic molecules
Vacuole
Contains cell sap (water amino acids salt water)
Isotonic
Same amount of conc in & out if the cell
Hypertonic
When the conc of solute is higher outside cells
Hypotonic
When the conc of solute is lowr outside the cells
What is passive transport across membranes
The movement of molecules through cell membranes without the use of energy by the cell
Facilitated diffusion
The movement of a molecule from an area of lower conc with the help of a protein channel/ carrier
Active transport across membranes
The movement of molecules through cell membranes against a concentration gradient at the cost of energy with help of a carrier protein
Flaccid in animal cells
Water leaves by osmosis
Cell shrinks and becomes flaccid
Plasmalised in plant cells
Cytoplasm, vacuole shrink
Membrane comes away
Water leaves cell by osmosis
Lysed animal cells
Water enters by osmosis
Cells swells and may burst
Turgid plant cells
Water enters by osmosis
Cytoplasm and vacuole swell
Becomes turgid
