– 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.
– 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.
– 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.
– Reproduction occurs by fission. Also by primitive type of sexual reproduction, by transferring DNA piece from one bacterial cell(+ strain) to other (- strain) (called cell Transduction)
– Smallest unicellular anaerobic organisms having no cellwall.
– Pathogenic in plants and animals.
Kingdom Protista –
– Unicellular eukaryotes.
– Primarily aquatic.
– Some have cilia and flagella.
– Reproduction sexual and asexual both.
– Fresh water or marine microscopic Planktons.
– Mostly photosynthetic and cheif producer in ocean eg. Diatomsand Golden algae (Desmids).
– Diatoms with cellwalls in two halves having Silica (indistructible).
– Diatomaceous earth is formed by cellwall deposits of Diatoms and used in polishing, filtration of oils and syrups, fire bricks and explosives.
– Photosynthetic yellow , green, blue, brown or red in colour.
– One longitudinal and other transverse two flagella.
– Gonyaulax causes Red tides.
– Fresh water forms.
– No cellwall, outer most layer pellicle.
– Two unequal flagella.
– Photosynthetic but also heterotrophic in absence of light ( Mixotroph).
Slime moulds –
– Body is an aggregation called ‘Plasmodium’( multinucleate, without cellwall, irregular in shape and can spreadover several feet ).
– Plasmodium produces fruiting body having spores with walls which are highly resistant and spread through wind.
– Fresh water or marine unicellular heterotrophs.
– Primitive relative of animals.
(a) Amoeboid Protozoans –
– Free living or parasites.
– Pseudopodia (false feet) formed eg. Amoeba ,Entamoeba.
(b) Flagellated Protozoans –
– Free living or Parasitic with flagella eg.Trypanosoma( causessleeping sickness).
(c) Ciliated Protozoans –
– With cilia eg. Paramecium(sleeper animalcule).
– Spore like stage in life eg. Plasmodium vivax.
Kingdom Fungi –
– Fungi are a group of achlorophyllous, heterotrophic organisms with cell wall without cellulose.
– Saprophyte or Parasite or Symbiotic.
– Useful and Harmful both.
– Prefer to grow in warm and humid places.
– Unicellular (eg. Yeast) to multicellular filamentous body calledmycelium.
– One unit of mycelium called hypha .
– Mycelia maybe coenocytic (no septum) or septate.
– Lichens – Symbiotic association of fungus and algae.
– Mycorrhiza – Symbiotic association of fungi with root of higher plants eg. Pinus.
– Reproduction –Vegetative : by fragmentation and by spores.Sexual: by gametes.
– Three steps in sexual reproduction
1) Plasmogamy – fusion of protoplasm.
2) Karyogamy – fusion of nuclei.
3) Meiosis of zygote.
– Grow on aquatic places or decaying wood or damp places or obligate parasite.
– Mycelium aseptate, coenocytic.- Reproduction – asexual by zoospores or aplanospores.
Sexual by zygospores.
– eg. Rhizopus(bread mould) and Albugocandida (causing white rust of crucifers).
Ascomycets (sac fungi)-
– Unicellular (eg. Yeast) or multicellular
– Saprophytic or parasitic.
– Maybe coprophillus (growing on dung) eg. peziza.
– Mycelium septate and branched.
– Reproduction – asexual by exogenously produced conidia.
sexually by Ascospares produced in asci present in fruiting body called Ascocarp.
– egAspergillus, Claviceps, Neurospora, Saccharomyces (yeast) etc.
Basidiomycetes (club fungi) –
– Grow on soil , logs or parasites ( rusts and smuts).
– Mycelium septate and branched and of two types 1) Uninucleate 2) Dikaryophase.
– Reproduction – vegetative by fragmentation sexualby two somatic cells giving rise to Dikaryophase.
– Dikaryophase makes fruiting body Basidiocarp having Basidia.
-Inside basidia (singular basidium) – Karyogamy and meiosis occours.
-Meiosis results in formation of four basidiopores.
Deuteromycetes (Fungi- imperfectil) –
– It is formed class – Group of Fungi whose complete life cycle is not known.-Saprophyte/parasite , mostly decomposers.- eg. Alternaria, colletotrichum, Trichoderma.
Kingdom Plantae –
– Eukaryotic, chlorophyll bearing autotrophic organisms.
– Only few members partialheterotrophs eg. Insectivorus plants (Bladder wort and Venus flytrap).
– Few parasites eg. Cuscuta
– Reproduction – vegetative,asexual and sexual.
– Life cycle shows alternation of generation.
– eg. Algae, Bryophytes,Pteridophyte, Gymnosperms and Angiosperms.
Kingdom Animalia –
– Eukaryotic, Heterotrophic organisms.
– No chloroplast and no cell wall.
–Holozoic mode of nutrition .
– Definite shape and size and capable of locomotion.
– Reproduction – sexual in general
– eg. frog, cockroach, cow, man etc.
Viruses, Viroids and Lichens –
Viruses – Connecting link between living and non living.
– Non cellular structure consisting of protein coat and Nucleic acid
– Can reproduce within a host cell.
– Host cell may be killed.
– Viruses which infect bacteria are called Bacteriophage.
– Tobacco Mosaic Virus (TMV)–
– Protein coat: – capsid consists of capsomers.