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Science 23rd of march osmosis (Osmosis (It is the diffusion of water…
Science 23rd of march osmosis
Diffusion
The sock can be smelt because sweat and other molecules are moving away from it and spreading out in the air. This is called diffusion.
The smell is strongest at the sock. The smell becomes weaker further away from the sock.
Molecules in liquids and gases are constantly moving and bumping into each other. This means that they tend to spread out. By contrast, solids cannot diffuse.
During diffusion molecules move from an area of high concentration to an area of low concentration.
They are said to move down a concentration gradient.
Diffusion is a passive process which means that no energy is needed.
Molecules diffuse until they are evenly spread and equilibrium is reached
The rate of diffusion depends on many factors, such as difference in concentration and distance particles have to move
Diffusion is the main way in which substances move over short distances in organisms
What substances move?
Oxygen
Food
Waste products
They are transported in the bloodstream, where they can diffuse in and out of cells
Breathing
Breathing involves the exchange of gases in the lungs; a
process that occurs by diffusion.
Oxygen in inhaled air diffuses through the lungs and into the bloodstream. The oxygen is then transported throughout the body
Carbon dioxide is the waste gas produced by respiration.
Carbon dioxide diffuses from body tissues into the bloodstream and is exhaled via the lungs.
Alveoli are the tiny air sacs at the end of the bronchioles, in which gas exchange occurs.
Osmosis
It is the diffusion of water molecules from a low concentration to a high concentration across a partially-permeable membrane
Dilute solutions have a high concentration of water molecules
Concentrated solutions have a low concentration of water molecules
Plant and animal cells have a membrane, this lets water and other small molecules through into the cell.
Root cells in plants get water through osmosis
Many root hairs increase the surface area, allowing it to absorb more water
In dilute solutions, osmosis can cause animal cells, such as red blood cells, to swell up and burst. This is called lysis
In concentrated solutions, water loss causes the cells to shrink. When this happens to red blood cells, it is called crenation.
In order to remain healthy animal cells need to maintain an isotonic water balance, this means that the concentration of water molecules need to be the same in and outside the cell
The kidney regulates the water and sugar levels