In biology, nothing is clear, everything is too complicated, everything is a mess, and just when you think you understand something, you peel off a layer and find deeper complications beneath. Nature is anything but simple.

~ Richard Preston, The Hot Zone: A Terrifying True Story

Thursday, 2 August 2012

Diffusion part 1 - 2 August 2012

So what is DIFFUSION?

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration.

Diffusion is a spontaneous process (no input of energy required). It can also be called as a passive process.

Substances tend to spread from an area where they are more concentrated to an area where they are less concentrated.

Two or more substances can become evenly distributed (reach equilibrium) even without external

Concentration Gradient

Firstly, what is a concentration?

Concentration is the amount of substance (in mass) divided by it's volume (in litres). In other words, a measure of the amount of a substance in a specific volume.

So, what is concentration gradient?

The concentration gradient is the change in concentration between two regions.

Here is an example of the concentration gradient:

From the graph, we can also say that difference in the concentration between points A and B is the concentration gradient between points A and B.

If the above graph shows the concentration of sugar at points A and B, sugar molecules will diffuse down the concentration gradient from point A to point B.

Things to note about concentration gradient and diffusion:

Firstly, particles diffuse down the concentration gradient.
The larger the concentration gradient, the faster the rate of diffusion.

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