On a hike with your friend Lianna, she runs out of water and tells you to hold on a second while they grab some water from the river next to the trail. You run after them, telling them that it’s not safe because there are a lot of dangerous things living in the water! Your friend doesn’t believe you, but agrees not to drink the water and you both decide to take a water sample back to class to test it.






At school, you have a microscope that allows you to see objects at 10x, 40x, and 400x. Your teacher tells you that at the maximum magnification, you’ll able to see the shape of objects that are 2-5 µm, but the depth of field is very small at that magnification.






120 nm Large virus (includes influenza virus)




150-250 nm small bacteria such as Mycoplasma




200 nm (200 to 500 nm) Lysosomes




(1 - 10 µm) the general sizes for Prokaryotes




2 µm E.coli - a bacterium




5 µm length of chloroplast




6 µm (3 - 10 micrometers) the Nucleus




9 µm Human red blood cell




(10 - 30 µm) Most Eukaryotic animal cells




(10 - 100 µm) Most Eukaryotic plant cells




90 µm small Amoeba




120 µm Human Egg




up to 800 µm large Amoeba


120 mm Diameter of an ostrich egg








Key:



1 millimeter (mm) = 1000 micrometers (µm)



1 micrometer (µm) = 1000 nanometers (nm)