What is Diffusion
themovement of moleculesfrom a region of itshigherconcentration to a region of itslowerconcentration
how do molecules in diffusion move
down a concentration gradient, as a result of theirrandom movement
what if a cell is surrounded by a cell membrane
canrestrict the free movement of the molecules
what is the certain cell membrane called and what does it mean
apartially permeable membrane- this means it allows some molecules to
cross easily, but others with difficulty or not at all
how does diffusion help organisms
o obtain many of theirrequirements
o get rid of many of theirwaste products
o carry outgas exchange for respiration
Where does the energy for diffusion come from?
All particles move randomly at all times
known as Brownian motion
energy for diffusion comes from kinetic energy of this random movement of molecules
and ions
Factors that Influence Diffusion
- Surface area
- Distance
- Temperature
- Concentration Gradient
how is water important as a solvent
o Dissolved substances can beeasily transportedaround organisms
o Digested food moleculesare in alimentary canal but need to bemoved to cellsall over the body
o Toxic wastes like urea and extra salts can mix with water, so the body can easily get rid of them in urine.
o important part of cytoplasm ensuringmetabolic reactions happenas necessary in cells
how can water move in cells by osmosis
in and out
what is osmosis
diffusion of water molecules from adilute solution to amore concentrated solutionacross apartially permeable membrane
what does a partially permeable memberane mean
it allowssmall moleculesthrough but not larger molecules
