IB Biology Sub-topic B2.1 Definitions

This page contains our IB Biology definitions for sub-topic B2.1. By learning each one of these definitions, you will fully cover the content for IB Biology 'Membranes and transport'.
active transport

The movement of substances across membranes usually against concentration gradients, requiring energy from ATP

amphipathic

A molecule's property of being both hydrophobic and hydrophilic

diffusion

The net passive movement of particles from areas of high concentration to areas of low concentration, requiring no energy

faciliated diffusion

The passive movement of particles from areas of high concentration to areas of low concentration via specific channel proteins

hydrophilic

Attracted to water (water-loving)

hydrophobic

Repelled to water (water-fearing)

osmosis

The movement of water from a region of low solute concentration to a region of high solute concentration, across a partially permeable cell membrane

peripheral protein

A protein on the surface of the plasma membrane

simple diffusion

The passive movement of particles from areas of high concentration to areas of low concentration across a semi-permeable membrane

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