- Classification is the Science of arranging organisms in series of groups and subgroups on the basis of their similarities and dissimilarities.
- Aristotle classified organisms on the basis of their habitat means the place where they live, in water, in air and on land
- We look for similarities among the organism which allows us to put them into different classes and then study them as a whole.
- Characteristics are details of appearance or behaviour.
- The characteristics that decide the broadest divisions among living organisms are independent of any other characteristic in their effects on the form and function of the organism
- The characteristic in the next level would be independent on the previous one and would decide the variety in the next level.
- Once a body design comes into existence, it will shape the effects of all subsequent design changes.
- Characteristics that come into existence are likely to be more basic than characteristics that have come into existence later.
- Some group of organisms have ancient body designs that have not changed very much and are referred to as primitive or lower organisms.
- Some group of organisms have acquired their particular body design relatively recently and are referred to as advanced or lower organism.
HIERARCHY OF CLASSIFICATION
- The kingdoms proposed by whittaker proposed has five kingdoms: Monera, protista, fungi, plantae and animalia.
- Woese introduced modification by dividing monera into archaebacteria and eubacteria.
- Classification is done by naming the sub-groups at various levels in the following scheme: kingdom, phylum, class, order, family, genus, species.
- A species include all organisms that are similar enough to breed and perpetuate.
Further classification is done by naming the subgroups at Various levels as given:
- Organisms in monera kingdom do not have a defined nucleus, organelles or multicellular body design.
- They may or may not have cell walls
- The mode of nutrition in organisms of monera kingdom can be autotrophic as well as heterophic.
- This group includes bacteria, blue-green algae or cyanobacteria, mycoplasma and anabaena.
- Organisms of this group are unicellular, eukaryotic and some of them organisms use appendages, such as hair-like cilia or whip-like flagella for moving around.
- Examples are unicellular algae, diatoms and protozoans
- Organisms in this group are heterotrophic, eukaryotic and use decaying organic material as food and are therefore called saprophytes.
- Many of these organisms have the capacity to become multicellular organisms at a certain stages in their lives.
- They have cell walls made of tough complex sugar called chitin.
- Yeast, mushrooms, aspergillus, penicillium and agaricus.
- Some fungal species live in symbiotic relationships, and these life-forms are called lichens.
- The organisms in this group are are multicellular, eukaryotes, autotrophs and use chlorophyll for photosynthesis
- All plants are included in this group.
- These include all organisms which are multicellular eukaryotes, without cell walls, and are heterotrophs.
- Plants in this group are predominantly aquatic and do not have well-differentiated body design fall in this group.
- Plants in this are commonly are called algae.
- Examples of thallophyta are spirogyra, ulothrix, cladophora and chara.
- Bryophytes are called the amphibians of the plants.
- The plants in this group do not have special tissues for conduction of water and other substances from one part of the plant body to another.
- Examples of bryophyta are moss and marchantia.
- The plant body is commonly differentiated to form stem and leaf-like structures.
- The plant body is differentiated into roots, stem and leaves and has specialised tissue for the conduction of water and other substances from one part of the plant body to another.
- Plants of pteridophyta are cryptogamae.
- Cryptogamae are plants with hidden reproductive organs.
- Phanerogams are plants with well differentiated reproductive tissues that ultimately make seeds.
- The plants of this group bear naked seeds and are usually perennial, evergreen and woody
- Pines such as deodar are example of gymnosperms
- The seeds of these plants develop inside an organ.
- These are also called flowering plants.
- Plant embryos in seeds have cotyledons i.e seed leaves.
- Monocots are plants with seeds having one cotyledon.
- Plants with seeds having two cotyledons are called dicots.