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Biology Essay : Importance of Diffusion in Organisms (25 marks)
Diffusion is the movement of particles from an area of high concentration to an area of low
concentration down the concentration gradient and it is a passive process so it doesn't
require any energy for it to occur
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The first is with action potentials
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Diffusion is also very important during
depolarization because this is where voltage gated sodium channels open and sodium ions
rapidly diffuse into the cell and significantly increases the membrane potential
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The next process which involves diffusion and is essential in living organisms is synaptic
transmission
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This allows a new action potential to form in the
postsynaptic neuron
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Synaptic transmission is useful for different processes such as gaseous exchange in
organisms
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This states that the higher the surface area, the steeper the concentration
gradient and the shorter diffusion distance gives the highest rate of Diffusion
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gradient
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Another organism which have effective gaseous exchange system are insects, this is where
oxygen enters the system via diffusion through the spiracles which are holes which can open
and shut and then it diffuses down the tracheal system
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Humans also have a very efficient gaseous exchange system as air enters through the nasal
passage or the mouth via diffusion then moves through the trachea, bronchi and the

bronchioles to the alveoli
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This is effective because there is a
high surface area due to there being millions of alveoli throughout the human body, there is a
short diffusion pathway as they are surrounded by capillaries which are 1 cell thick and
constant ventilation allows the concentration gradient to remain steep

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