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Revision, movement and cells - Coggle Diagram
Revision, movement and cells
Living organisms have certain life processes in common. There are seven things that they need to do to count as being alive.
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Movement - all living things move, even plants
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It can be easy to tell if something is living or not. A teddy bear might look like a bear, but it cannot do any of the seven things it needs to be able to do to count as being alive.
A car can move, it gets energy from petrol (like nutrition and respiration), it might have a car alarm (sensitivity), and it gets rid of waste gases through its exhaust pipe (excretion). But it cannot grow or make baby cars. So a car is not alive.
Cells are the basic building blocks of all animals and plants. They are so small, you need to use a light microscope to see them.
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You can focus the image using one or more focusing knobs. It is safest to focus by using the knobs to move the stage downwards, rather than upwards. There is a chance of the objective lens and slide colliding if you focus upwards.
Microscopes often have three or four objective lenses on a turret that you can turn. It is wise to observe an object using the lowest magnification lens first. You may need to adjust the focus and the amount of light as you move to higher magnifications.
Microscope view of plant cells
Onion cells are easy to see using a light microscope. Here is a typical method for preparing a slide of onion cells:
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When you observe cells, it is usual to make a drawing of what you see. Very often there is so much to see that you can only aim to draw part of it:
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if the eyepiece magnification is ×10 and the objective lens magnification is ×40:
total magnification = 10 x 40 = ×400 (400 times)
