5.3 Diffusion Flashcards
Diffusion
Net movement of particles from a region of high concentration to low concentration
Passive process
Continues until there is a concentration equilibrium between 2 areas
Why does diffusion take place?
Particles in liquid/gas have kinetic energy
Movement is random and unequal distribution of particles becomes equal
Particles don’t stop moving at equilibrium- just movement in both directions is equal
Why is diffusion faster with short distances?
Particles move at high speed and are constantly colliding which slows down movement overall
Factors affecting rate of diffusion
Temperature
Concentration difference
Diffusion distance
SA:V ratio
Effect of temperature on diffusion
Higher temperature- higher rate of diffusion
Particles have more kinetic energy, move at higher speeds
Effect of concentration difference on diffusion
Greater the concentration gradient, faster rate of diffusion
Overall movement from the high concentration to low concentration will be larger
What is simple diffusion?
Diffusion in the absence of a barrier or membrane
Why are membranes partially permeable?
Non polar molecules can diffuse through freely Ions cannot pass through easily Polar molecules (eg H2O) can diffuse through but at slower rates
Factors affecting rate of diffusion across membranes
Surface area - larger SA, higher rate of diffusion
Thickness of membrane - thinner membrane, higher rate of diffusion
Facilitated diffusion
Diffusion across a membrane through protein channels
Passive process
Factors affecting rate of facilitated diffusion
Temperature Concentration gradient Surface area Membrane thickness Number of channel proteins present
