What are the factors affecting the rate of diffusion
Surface area
Distance
Concentration gradient
Temperature
Size of the particles
Type of particles
How does surface area affect the rate of diffusion
The larger the surface area over which diffusion can take place, the faster the rate of diffusion.
How does distance affect the rate of diffusion
The greater the distance the longer the particles take to move randomly down the concentration gradient and the slower the rate of diffusion.
How does the concentration gradient affect the rate of diffusion
The greater the difference in concentration between the two sides of the membrane (the steeper the concentration gradient), the faster the rate of diffusion.
How does temperature affect the rate of diffusion
The higher the temperature, the more kinetic energy the particles have, so they move faster and the faster the rate of diffusion.
How does the size of the particles affect the rate of diffusion
Larger molecules move more slowly and do not fit as easily between the phospholipids, so the slower the rate of diffusion.
How does the type of particle affect the rate of diffusion
Large, polar or charged molecules and ions require a transport protein to cross the membrane. Therefore the more transport proteins in the membrane the faster the rate of diffusion.
Why does the rate of uptake plateau when increasing the concentration gradient for facilitated diffusion
The number of transport proteins becomes limiting.