S.C.912.L.15.6 Classification
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You need to know the distinguishing characteristics of the domains and kingdoms of living organisms.
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You need to know how organisms are classified based on evolutionary relationships.
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You need to explain the reasons for changes in how organisms are classified.
TUTORIALS
Classification of Living Things
Classification Using DNA
EOC Practice Questions
Diagramming Diversity I
Diagramming Diversity II
Taxonomy is the field of biology that deals with classifying organisms. Taxonomists classify organisms based on:
1. Analysis and comparisons of their physical structures
2. Patterns of embryological development
3. Chemical process
4. DNA
These data are used to group organisms in ways that reflect evolutionary relationships. Taxonomists now try to group organisms based on evolutionary relationships and shared ancestry.
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AUTOTROPH: an organism that makes its own food
HETEROTROPH: an organism that feeds on other organisms
Important Details
Fungi and Animals are HETEROTROPHIC
Plants are AUTOTROPHIC
Animal cells lack a cell wall.
Plants and animals are multicellular
Eukarya domain includes more complex living things than the Archaea or Bacteria domains because eukaryotes have a greater variety of genetic material than prokaryotes
Algae can be unicellular, or they may be large, multicellular organisms. Algae are now considered protists and not plants because they do not have organs or specialized tissue. Algae lack the true stems, leaves, or roots of the more complex, higher plants.
Plants are multicellular, sessile (non-moving), and able to create their own food (autotroph)
The MOST important reason that Archaea and bacteria belong to separate biological domains is because archaea transfer genes similar to an eukaryote, and they have a different genetic history than bacteria.
Viruses are NOT classified as living things because they are not made up of cells and can only reproduce by using another organism.
In modern taxonomy there are 8 levels of classification: (as you move from the top to the bottom of this hierarchy, each classification is more specific)
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The goal of evolutionary classification is to group species into larger categories that reflect lines of evolutionary descent, rather than overall similarities and differences
A Phylogenic tree, is a diagram whose branches show the evolutionary links among different groups. Phylogenic trees can provide a great deal of information about the ancestor and descendants of organisms. The lengths of the lines representing the branches may indicate the amount of time since a group of organisms evolved from a common ancestor
Plants fungi and animals are thought to have evolved from Protista.
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You need to explain the reasons for changes in how organisms are classified.
Many changes in classification have resulted from advances in technology. For example microorganisms were discovered after the invention of the microscopes. Most recently, prokaryotes have been divided into two kingdoms. That changed was based on more knowledge of the chemicals that make up these organisms.
In earlier classification systems fungi where classified as plants. Fungi are now classified in a different kingdom because they are heterotrophs and cannot make their own food.
Other changes have resulted from an acceptance of the theory of evolution by natural selection and an understanding of DNA