Diffusion Flashcards
What is diffusion?
Diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration.
Where does diffusion happen?
Diffusion happens in both solutions and gases. That’s because the particles in these substances are free to move about randomly. The simplest type is when different gases diffuse through each other.
What 3 things affect the rate of diffusion?
The bigger the concentration gradient, the faster the rate of diffusion. This is because the net movement from one side is greater.
The larger the surface area of the cell membrane, the faster the rate of diffusion. This is because more particles can pass through at once.
The higher the temperature, the faster the rate of diffusion. This is because the particles have more energy, so move around faster.
How are cell membranes used for diffusion?
The cell membrane holds the cell together and controls what goes in and out. Dissolved substances can move in and out of cells by diffusion.
Only very small molecules such as oxygen, glucose, amino acids and water can diffuse through cell membranes.
Big molecules like starch and proteins can’t fit through the membrane. Particles flow through the cell membrane from where there’s a higher concentration to where there’s a lower concentration. They’re only moving about randomly, so they go both ways.
If there’s a lot more particles on one side of the membrane, then there’s a net (overall) movement from that side.
