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B1 - Cells and Organisms - Coggle Diagram
B1 - Cells and Organisms
B1.1
1km = 1000m, 1m = 100cm, 1cm = 10 mm, 1mm = 100um, 1um = 1000 nm
Light microscopes use a beam o flight to form an image of an object and the best can magnify around 2000 times (X200).
To calculate the size of an object, Magnification = size of image / size of real object
Light microscopes magnify up to X20000, and have a resolving power of about 200nm.
Electron microscopes magnify up to X2000000, and have a resolving power of around 0.2nm.
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B1.6 Diffusion
Diffusion is the spreading out of particles of any substance, in a solution or a gas. This results in a net movement from an area of higher concentration to an area of lower concentration, down a concentration gradient. The motion of all the particles causes them to bump into each other, and this moves them all around.
If there is a big difference in concentration between two areas, diffusion will take place quickly. Many particles will move randomly towards the area of low concentration, and only a few in the other direction
On the other hand, if there is only a small difference in concentration between two areas, the net movement by diffusion will be quite slow. The number of particles moving into the area of low concentration by random movement will only be slightly more than than the number of particles that are leaving the area.
In general, the greater the difference in concentration, the faster the rate of diffusion. This difference is called the concentration gradient. The bigger the difference, the steeper the concentration gradient and the faster the rate of diffusion
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Temperature also affects the rate of diffusion. The higher the temperature, the move quickly the particles will move around. When this happens, diffusion takes place more rapidly as the random movement of the particles speeds up.
Dissolved substances move in and out of your cells by diffusion across the cell membrane. E.g. sugars such as glucose, gases such as oxygen and CO2, and waste products such as urea from the breakdown of amino acids in your liver.
The oxygen you need for respiration passes from the air in your lungs into your red blood cells through the cell membranes through diffusion. It moves from high-low gradient