22.1.4 comparing the relative sizes of molecules……………….. You have 3 minutes to answer the following: Give two reasons why we use light microscopes and give the main reason why we use the electron microscope.
3What units of measurement do we use in biology? International System. Why?So that the same units are used in every country in the world.Copy the following information.
4SI units (international system) 1 metre (m) = 1m1 millimeter (mm) = 1mm = 1x10-3m1 micrometre (μm) = 1μm = 1x10-6m1 nanometre (nm) = 1nm = 1x10-9m1 centimetre cubed = 1cm31 decimetre cubed = 1dm3 (deci = 1/10 of a metre = 10 cm)1 second = 1s1 minute = 1min1 hour = 1hConcentration is measured in mol dm-3This just means mols per decimetre cubed.
5Activity In pairs: Consider the following structures: Put them in order of size starting with the smallest.a hydrogen molecule.a human cheek cell.a cell organelle(mitochondrion).a virus.a bacterium.plasma membrane
6Answers a hydrogen molecule. plasma membrane a virus. a bacterium. a cell organelle(mitochondrion).a human cheek cell.See page 10 of your text book.