British Sign Language Glossaries of Curriculum Terms

BSL Environmental Science Glossary - Passive transport definition

Definition: Passive transport is the passive diffusion of substances across a membrane from a high concentration to a low concentration of substance. So if there are ten molecules on one side of the membrane and only two on the other side, the substances will naturally diffuse from the higher concentration to the lower concentration without any energy being used to drive this transport. The diffusion will continue until the numbers are equal on both sides, reaching homeostasis.

An example is the spraying of perfume. A perfume bottle has a high concentration of perfume. When the bottle is sprayed onto your neck, it is going from a high concentration to a low concentration of perfume, into the air and onto your neck. There is no energy involved in the dispersal of perfume when it is sprayed, yet the perfume is easily transported to an area of low concentration, your neck.

This is passive transport.