| 311 Syllabus |
Classification of Living Organisms |  |
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| Fucus a member of the Phaeophyta (Brown Algae) |
Science is an organized attempt to use our mental and physical faculties to understand the Cosmos.
The first step in this process is identification & classification.
 Chlorella is a unicellular member of the Chlorophyta (Green Algae) |
 Spirogyra is a filamentous member of the Chlorophyta (Green Algae) |
 Pallavicinia a member of the Bryophyta (Liverworts & Moss) |
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All of these have similar pigments, especially Chlorophyll a & b. However, Chlorella and Spirogyra are aquatic while Pallavicinia is terrestrial. |
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All human cultures have striven to identify and organize biota into categories.
Plants that grow in the ocean can be separated from land plants based on their habitat.
They might be classified on the basis of Color or Structural Complexity.
Traits used to separate organisms can also be used to group them.
Some traits may be better for classification than others!!!!!!!
What are the similarities & dissimilarities of the two organisms below?
 Ulva (Sea Lettuce) a member of the Chlorophyta that lives in the ocean. |
 This a "filmy fern" leaf a member of the Pterophyta (Ferns). It grows on land but must be continuously moistened in order to survive |
| Ulva is an aquatic plant. Ulva is Marine and lives in salt water. Ulva is Green & has the same photosynthetic pigments as Ferns Ulva is only two cells thick and has no Organs. |
Fern is semi-aquatic. Fern requires fresh water. This Fern has unicellular areas but it is basically multicellular. This Fern has Organs |
The differences between terrestrial plants and animals are readily apparent as are the major differences between elephants and ants, or a Royal Palm and a Moss.
However, the more we learn about the complexity of living organisms the greater is our ability to accurately group and separate species that appear similar.
The invention of the light microscope & the electron microscope revealed new worlds of living things and provided finer criteria for classification.
 Euglena (Euglenophyta) Cell seen with a Light Microscope |
 Algal Cell viewed with an Electron Microscope |
The emergence of Biochemistry & Molecular Biology have provided new, powerful ways to distinguish organisms and understand their relationships.
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