Biological Classification

Systems Of Classification

• Earliest Classification was given by Aristotle. Divided plants into herbs, shrubs and trees. Animals into those with RBC’s and those who do not have it.
• Two kingdom classification : Given by Carolous Linnaeus − Plant kingdom and Animal kingdom.
• Five kingdom classification : By R. H. Whittaker. Monera, Protista, Fungi, Plantae and Animalia are the five kingdoms.

Kingdom Monera

• Has bacteria a sole member.
• Bacteria can have shapes like : Coccus (spherical), Bacillus (rod-shaped), Vibrio (comma shaped) and sprillum (spiral shaped).
• Bacteria found almost everywhere and can be Photosynthetic autotrophs, Chemosynthetic autotrophs or Heterotrophs.

Archaebacteria

• Halophiles (salt-loving)
• Thermoacidophiles (in hot springs)
• Methanogens (in marsh and in gut of ruminant animals. Produce methane gas.)

Eubacteria

• Photosynthetic autotrophs like Cyanobacteria. Some like Anabaena have specialised cells called heterocysts for nitrogen fixation.
• Chemosynthetic autotrophs : Oxidise various inorganic substances like nitrates/nitrites, ammonia and use released energy for their ATP production.
• Heterotrophic bacteria : Decomposes,help in making curd, production of antibiotics, Nitrogen fixation, cause diseases like cholera, typhoid.

Mycoplasma : Completely lack cell wall. Smallest living cells. Can survive without oxygen. Pathogenic in animals and plants.

Kingdom Prostita 

• All single celled eukaryotes
• Forms a link between plants, animals and fungi.

1.Chrysophytes 

• Cell walls have silica and cell walls overlap to fit together like a soap box.
• Their accumulation forms ‘Diatomaceous Earth’.
• Used in polishing, filtration of oils and syrups.
• Has diatoms and golden algae.

2.Dinoflagellates

• Marine, photosynthetic, cell wall has cellulose.
• Two flagella − one longitudinal and other transversely in a furrow between wall plates.

3.Euglenoids

• Have protein rich layer ‘pellicle’ which makes body flexible.
• Photosynthetic in presence of sunlight but become heterotrophs if they do not get sunlight.

4.Slime Moulds

• Saprophytic protists
• Form aggregates to form plasmodium grows on decaying twigs and leaves.
• Spores have true walls which are extremely resistant and survive for many years.

5.Protozoans

• Amoeboid : Catch prey using pseudopodia, e.g., Amoeba.
• Flagellated : More flagella. Cause disease like sleeping sickness e.g., Trypanosoma.
• Ciliated : Have cilia to move food into gullet and help in locomotion. e.g., Paramecium.
• Sporozoans : Have infective spore like stage in life cycle, e.g., Plasmodium which causes Malaria.

Kingdom Fungi

• Non chlorophyllous hyphae
• Network of hyphae called mycelium
• Cell wall of chitin and polysaccharides
• Grow in warm and humid places
• Saprophytic, parasitic, symbiotic (Lichen) e.g., Puccinia (rust causing), Penicillium.

Classes Of Fungi

Phycomycetes

• Grow on decaying wood
• Mycelium septate
• Spores produced endogenously
• Asexual reproduction by Zoospores or Aplanospores

e.g., Rhizopus, Albugo.

Ascomycetes

• Also known as ‘sac fungi’
• Mycelium branched and septate
• Spores : Asexual spores are called conidia produced exogenously on the conidiophores.
• Sexual spores, called ascospores, are produced endogenously in an ascus, which is produced inside the fruiting body called Ascocarp.

e.g., Aspergillus, Neurospora.

Basidiomycetes

• Mycelium septate.
• Asexual spores generally are not found.
• Vegetative reproduction by fragmentation.
• Sexual reproduction by fusion of vegetative or somatic cells to form basidium produced in basidiocarp.
• Basidium produced four basidiospores after meiosis.

e.g., Agaricus, Ustilago.