Osmosis a Part of Diffusion?

Headline: Osmosis a Part of Diffusion?

Today, we went through Diffusion and Osmosis which is under the topic, Transport in Living Things. People usually think that osmosis and diffusion work in the same way. Actually, osmosis and diffusion are different from one another. Osmosis is a type of diffusion.

I learnt that diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. As for osmosis, it is the net movement of water molecules from a region of higher concentration of water molecules to a region of lower concentration of water molecules through a partially-permeable membrane.

The 3 differences between osmosis and diffusion are:

1. Diffusion can occur in solid, liquid or gaseous state but osmosis can only occur in the liquid state.

• Diffusion in solid (e.g. copper (II) sulfate crystals being embedded on colourless agar)
• Diffusion in liquid (e.g. crystals of potassium permanganate diffuse in liquid)
• Diffusion in gas (e.g. the scent of perfume in the air)

2. Diffusion is able to take place with/without a partially-permeable membrane but osmosis can only take place with a partially-permeable membrane.

• In some cases, both big and small molecules are able to pass through the partially-permeable membrane in diffusion.
• Only small water molecules are able to pass through the partially-permeable membrane in osmosis.

3. Diffusion involves movement of any molecules while osmosis involves movement of water molecules only.

I also learnt that both osmosis and diffusion occur in living organisms. For instance, diffusion of gases can happen in both plants and animals. In addition, diffusion of digested food into the bloodstream from the small intestine also occurs in animals. As for osmosis, it occurs in both plants and animals cells. The membranes in the cells are partially permeable.

When the concentration of water molecules outside the cells are lower than the water molecules in the cells, the water in the cells will leave through osmosis and causes the plant cells to turn flaccid and causes the animals cells to shrivel up. As for when the water molecules outside the cells are higher than the water molecules in the cells, the water will go in the cells by osmosis and causes the plant cells to turn flaccid and causes the animal cells to swell and burst.

(Example of plant cells undergoing osmosis)



Sources: Google Images