Life Forms Classification and Phylogeny

Study Notes

Life is classified into three main kingdoms: Fungi, Plantae (Plants), and Animalia (Animals).
Plants (Producers): Autotrophic, possess cell walls, and perform photosynthesis.
Animals (Consumers): Heterotrophic, lack cell walls, and cannot perform photosynthesis.
Fungi (Decomposers): Heterotrophic, possess cell walls, but cannot photosynthesize.

Organisms evolve from prokaryotic (unicellular) to eukaryotic (multicellular) structures.
Five Kingdom System was established to classify life forms based on complexity and nutritional modes.

Includes all bacteria and blue-green algae.
Characterized by unicellularity, prokaryotic cells, and the absence of distinct nuclei or organelles.
Bacteria can be autotrophic or heterotrophic, reproducing mainly via binary fission.
Examples include Staphylococcus aureus and Salmonella typhi.

Eukaryotic and non-green organisms that are heterotrophic.
Their cell walls are made of chitin, and they commonly feed on decaying matter.
Reproduction can be sexual or asexual.
Examples are Baker’s yeast, Aspergillus, and mushrooms.

High biodiversity necessitates structured classification for study and understanding.
Carl Linnaeus pioneered the binomial nomenclature system.
Haeckel and Chatton contributed to expanding the classification system.
Robert Harding Whittaker introduced the widely accepted five-kingdom system in 1969.

Classified into Prokaryotes (like bacteria) and Eukaryotes (like protozoa, fungi, and algae).
Viruses are distinct and are not classified as living organisms but as entities at the edge of life.

Bacteria: Size ranges from 1 mm to 10 mm, unicellular, reproduce by binary fission.
Protozoa: Approximately 200 mm, eukaryotic, can be symbiotic or pathogenic.
Fungi: Size between 10 mm to 100 mm, thrive on decaying organic matter, reproduce both asexually and sexually.
Algae: Size from 10 mm to 100 mm, aquatic, photosynthetic, and generally eukaryotic.
Viruses: Size ranges from 10 nm to 100 nm, dependent on host cells for reproduction, cause various diseases in plants and animals.

Practical activities include observing microorganisms from curd or pond water to learn about their diversity and characteristics.
Explore the size scale of microbes, from meters down to nanometers.

Classification helps in understanding the vast diversity of life and their relationships in the ecosystem, addressing their nutritional and structural complexities.