Key Concepts: Diffusion

Diffusion is the process of particles moving from an area of higher concentration to an area of lower concentration. This happens until the particles are evenly spread out, at which point equilibrium is reached.
The particles move by random motion, and no energy is needed for the diffusion process to occur, making it a type of passive transport.
Diffusion is a crucial process in biological systems. For example, oxygen diffuses from the air in the lungs into the blood, while carbon dioxide diffuses out of the blood into the lungs to be exhaled.
The rate of diffusion is affected by several factors. These include the concentration gradient (the difference in concentration between two locations), the temperature (higher temperatures increase the energy of the particles and therefore the rate of diffusion), and the surface area over which diffusion can occur.
Diffusion occurs in liquids and gases and not solids because the particles in solids do not have the freedom to move around. In gases and liquids, particles can move freely and mix with one another.
Osmosis is a specific type of diffusion that occurs with water molecules. Osmosis is the diffusion of water from a dilute (less concentrated) solution to a concentrated solution through a permeable membrane.
The cell membrane in cells is selectively permeable, meaning it allows certain types of substances to pass through while blocking others. This allows important processes involving diffusion, such as gas exchange and nutrient absorption, to take place.
Active transport, though not a form of diffusion, is an important concept related to it. It’s a particle movement method that requires energy, enabling substances to move against the concentration gradient.
When studying cells, understanding diffusion is key as it explains how substances, such as nutrients or waste, enter or exit cells. Additionally, it explains the behaviours of cells in different solutions, i.e., hypertonic, hypotonic or isotonic surroundings.