and what's a good way to remember it? My teacher said this would be on our final.
Early systems of classification used only what the organism looked like and their natural relationships. (Ex: An apple tree looks like and seems to grow like a pear tree. They both use the sun to make their food.)
With the gigantic advancements in science, classification has changed dramatically. Now organisms are classified by numerous means including :
a) morphology..how they are formed
b) cellular organization...multi or unicellualr
c) genetic simularities...do they both have RNA
d) embryology...how does the embryo begin & through what stages doe it go
e) evolution...how did it evolve
f) physical appearance
Note: Some organisms have been reclassified. Although they look very similar, their genetics demonstrates they should be classified differently.