5.3 - Diffusion Flashcards
What type of movement is diffusion
Passive
Where does passive movement get its energy from
Utilises energy from natural motion of particles rather than energy from another source
Definition of diffusion
Net movement of particles from a region of higher concentration to a region of lower concentration. Continues until there is equilibrium between two areas.
Definition of equilibrium
Balance or no difference in concentrations
How do the particles in diffusion move and what does their movement cause?
Particles in a gas or liquid have kinetic energy. Movement is random.
Unequal distribution becomes equal.
Why does a short distance increase rate of diffusion
Particles move at high speed so constantly collide, slowing down diffusion. Short distance means less time is spent diffusing as less collisions would’ve taken place.
Why are cells microscopic
Shorter distance for diffusion
Reactions need to get substrates quick enough
ATP would be supplied too slowly to energy requiring processes if cell was large
How does temperature affect rate of diffusion
Higher temperature higher rate. More kinetic energy, particles move at greater speed.
How does concentration difference affect rate of diffusion
Greater difference between two regions, greater rate. Overall movement form higher to lower is larger.
Simple diffusion
Absence of barrier or membrane
When can particles diffuse across a membrane
If the membrane is permeable to them
Non polar
They can diffuse down the concentration gradient
Why are membranes not easily permeable to ions
Hydrophobic interior repels ions
Ions cannot easily pass through
Factors affecting rate at which molecules diffuse across membrane
Surface area
Larger = higher rate
Thickness of membrane
Thinner = higher rate
Facilitated diffusion
When polar molecules and ions diffuse through a membrane via a protein channel
Describe permeability of membranes with protein channels
Selectively permeable
Most protein channels specific to one ion or molecule
