A-Level Biology - Diffusion - Simple & Facilitated | Factors Affecting Diffusion (2027/28 exams)
Share
Summary
An overview of diffusion processes across cell membranes, covering the definition of diffusion, the distinction between simple and facilitated transport, and the factors that influence the rate of movement.
Highlights
Defining Diffusion00:00:23
Diffusion is defined as the net movement of particles from an area of higher concentration to lower concentration. It is a passive process driven by the kinetic energy of particles, continuing until equilibrium is reached.
Simple vs. Facilitated Diffusion00:01:46
Simple diffusion allows small, non-polar molecules to pass directly through the phospholipid bilayer. Conversely, facilitated diffusion uses channel or carrier proteins to assist polar or larger molecules in crossing the membrane.
Factors Affecting the Rate of Diffusion00:03:49
The rate of diffusion is influenced by temperature (higher energy increases movement), the steepness of the concentration gradient, the total surface area of the membrane, and the density of channel or carrier proteins available.