How do you classify living things?

Question

and what's a good way to remember it? My teacher said this would be on our final. 

Answer 1

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.

 

Answer 2

Living things are classified based on various criteria first amongst them is presence of envelope around the genetic material DNA, thus living things not having nuclear envelope are classified as prokaryotes (e.g. bacteria) while living things that possess nuclear envelope are classified as eukaryotes (e.g. most plants and animals).

Briefly all living beings are classified under the 5 kingdom classification which are as follows-

1. Monera- comprises of single celled organismas that do not have nucleus. e.g. Bacteria

2. Protista- comprises of single celled organisms that have nucleus. e.g. algae, amoeba

3. Fungi- multicellular and nucleated, and absorb nutrients generally by decomposing them. e.g. molds, mushrooms and Yeast.

4. Plants- Mostly immobile organisms that can produce their own food as they have chlorophyll. e.g. Moss, Fern, Pine, Wheat and Potato.

5. Animals- mostly mobile multicellular organisms that are dependent on plants or other animals for food. e.g. Fish, frog, Lizard, Turkey and Lion.