A flatworm with a large surface-area-to-volume ratio and a short diffusion pathway
© Richard Carey/Alamy Stock Photo
Diffusion is the net movement of particles (molecules or ions) from a high to a low concentration. Some students state in exam answers that diffusion occurs along a concentration gradient. This would not be credited by examiners – diffusion is always down a concentration gradient. Diffusion is a pretty slow process because it is dependent on the kinetic energy of the molecules or ions, which move in random directions.
The rate of diffusion is determined by three factors.
Your organisation does not have access to this article.
Sign up today to give your students the edge they need to achieve their best grades with subject expertise
Subscribe
