Diffusion part 2 - 2 August 2012

Applications of diffusion in Biology

Example 1

To stay alive, the amoeba which is a unicellular organism needs to obtain nutrients and remove waste efficiently by the process called diffusion.

Example 2

Chemical substances must be able to move from one place to another in order to keep the living organisms alive and growing. For example, food substances need to move from one cell to another, move in & out of the cell and move from one part of the cell to another.



One way through these processes can occur is by diffusion across membranes.

Example 3

There are 2 types of membranes - The partially permeable membrane and the permeable membrane



Partially permeable membrane

A partially permeable membrane allows some substances to pass through.

Permeable membrane


A permeable membrane allows all substances to pass through.

Diffusion across a permeable membrane

An example of a partially permeable membrane is the visking tubing.

Other examples

• Movement of carbon dioxide during photosynthesis.

• Movement of oxygen and carbon dioxide in animals.

Conclusion

• Diffusion is an important process where substances are moved without use of energy.
•  It is the net movement of particles (or molecules; or ions) from a region of higher concentration to a region of lower concentration.
•  Thus the movement is down a concentration gradient.
• It is important to bear in mind that:
  – The movement is random.
  – The greater the concentration gradient, the faster the
  rate of diffusion.