Demerits Of Two Kingdom System

- Aristotle classified organisms for the first time.

- Two kingdom system includes – Plantae & Animalia.

Demerits of Two Kingdom system

- No difference in Eukaryotes and Prokaryotes.​

- Heterotrophic Fungi kept in Plantae.

- Five kingdom system is given by R.H Whittaker (1969) viz. Monera, Protista, Fungi, Plantae and Animalia.

Kingdom Monera –

- Prokaryotic unicellular organisms.

- Most abundant.

- Also live in extreme habitats viz. Hotsprings, Snow etc. as endoparasite etc.

-  eg. Bacteria.

- Some bacteria are autotrophic others are heterotrophic.

Archaebacteria –

- Cellwall different from other bacteria.

- Live in most harsh habitats eg. Halophile.

- Methanogens are found in the gut of ruminants and produce methane (CH4) gas.

Eubacteria –

- True bacteria.

- Rigid cellwall with or without flagellum.

- Cyanobacteria( Blue green algae) are also included in this group.

- Cyanobacteria are Photosynthetic autotrophs, unicellular, colonial or filamentous, with gelatinous sheath.

- Have Heterocyst for N2fixation eg. Nostoc, Anabaena, Oscillatoria, Rivularia, Gloeotrichia etc.