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BIOLOGY 9H (Diffusion & Osmosis): Diffusion

This guide will provide a variety of topics from which students can choose and begin the research process for Diffusion and Osmosis.

What is Diffusion?

Diffusion - The movement of molecules from an area of higher concentration to an area of lower concentration.

Particles in a liquid and a gas move continuously. Because of this movement, particles will spread themselves evenly throughout a liquid or a gas.

If there is a situation where particles of a substance are in a higher concentration, they will move from this region to where they are in a lower concentration.  Diffusion is a spreading out and mixing process.

It is important to remember that the particles:

  • will move in both directions, but there will be a net movement from high to low concentration
  • will end up evenly spread throughout the liquid or gas, but will continue to move

Diffusion is an essential process in cells. They need glucose and oxygen for respiration, which move into them by diffusion. Respiration produces carbon dioxide and water which leave cells by diffusion. (Water actually leaves cells by osmosis, which is the diffusion of water across a membrane.)

 

SOURCE:  https://www.bbc.co.uk/bitesize/guides/ztrgng8/revision/1

Examples of diffusion in biological systems

IN A LEAF

 

IN THE LUNGS

 

LIVER CELLS

SOURCE:  https://www.bbc.co.uk/bitesize/guides/ztrgng8/revision/1

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Diffusion Explained

This video uses a real life example and mentions concentration gradients, passive transport, facilitated diffusion, and explains why diffusion is critical for all organisms. In addition, this video discusses factors that can affect the rate of diffusion.

Time-stamped Table of Contents: 00:00 Intro 0:57 Relating intro event to diffusion 1:45 Diffusion explained 2:57 Molecules still move at equilibrium! 3:33 Diffusion is passive transport 3:45 Facilitated diffusion 4:22 Some factors that can affect rate of diffusion 6:35 Why care about diffusion?

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