Chapter 2 : Biological Classification

The process of grouping organisms based on certain similarities.

Carl Linnaeus

It did not distinguish between eukaryotes and prokaryotes, unicellular and multicellular organisms, and photosynthetic and non-photosynthetic organisms.

Monera, Protista, Fungi, Plantae, and Animalia

Cell structure, Body organisation, Mode of nutrition, Reproduction, Phylogenetic relationship

Archaebacteria, Eubacteria.

Halophiles, Thermoacidophiles, Methanogens

(1)Extreme Salty areas (2)Hot springs (3)Marshy areas&guts of ruminent animals

Photosynthetic autotrophs, unicellular, colonial, filamentous. Cells covered with mucilaginous sheath.Function - Fix atmospheric nitrogen in specialized cells called heterocysts.eg:Nostoc&Anabaena

Oxidise compounds like Nitrites,Nitrates&ammonia. Energy released during this process is used for ATP synthesis.

Cholera,Typhoid, Tetanous(In humans),Citrus canker(In plants)

Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds& Protozoans

R.H. Whittaker

Coccus (Spherical), Bacillus (Rod), Vibrio (Coma), Spirillum (Spiral)

Produce methane from cow dung,hence it is used in the production of biogas

Excessive growth of cyanobacteria in polluter water bodies is called algal bloom

-Production of curd from milk

-Production of antibiotics

-Helps in nitrogen fixation of leguminous plants

Includes Diatoms&Desmids(golden algae)

Desmids are chief producers of the ocean

Cell wall made of silica thus indestructable

Cell wall deposits of Diatoms over millions of years form the Diatomaceous earth.

-Used in polishing

-Filtration of oil and sugar

-Used as fire retardant

Excessive growth of red dinoflagellate(Gonyaulax) gives red colour to the sea.This is known as red tide. Toxins released during red tide may kill aquatic organisms.

Have a Protein rich body layer is called Pellicle which gives flexibility to the body.In presence of sunlight - Photosynthetic, Deprived of sunlight - heterotrophic

Eg : Euglena

Ancestors of Fungi, Saprophytic protists, During favourable condition the form an aggregation called Plasmodium

(1) Amoeboid protozoans eg: Amoeba,Entamoeba

(2) Flagellated protozoans eg: Trypanosoma (causes African sickness)

(3) Ciliated protozoans eg: Paramecium

(4) Sporozoans eg: Plasmodium (causes Malaria)

Network of hyphae in fungi is known as Mycelium

(1) Plasmogamy - Fusion of protoplasm

(2) Karyogamy - Fusion of two nuclei

(3) Dikaryophase - The condition where, After plasmogamy the two nuclei may remain as such without fusion

Morphology of mycelium, Mode of spore formation & Fruiting bodies

Phycomycetes, Ascomycetes, Basidiomycetes & Deuteromycetes

Mycelium - Coenocytic

Fruiting body - Absent

Asexual spore - Zoospores

Sexual spore - Zygospores

Eg: Rhizopus, Albugo, Mucor

Mycelium - Septate

Fruiting body - Ascocarp

Asexual spore - Conidia

Sexual spore - Ascospores

Eg: Penicillium, Yeast, Aspergillus, Claviceps, Neurospora

Mycelium - Septate

Fruiting body - Basidiocarp

Asexual spore - Absent

Sexual spore - Basidiospores

Eg: Agaricus, Puccinia, Ustilago

Mycelium - Septate

Fruiting body - Absent

Asexual spore - Conidia

Sexual spore - Absent

Eg: Alternaria, Colletotrichum, Trichoderma

Because they lack perfect or sexual stage.When their sexual stages are known they are moved to either Ascomycetes or Basidiomycetes.

Insectivorous plants - Venus fly trap, Bladderwort

Parasite - Cuscuta

Dimitri Ivanowsky

M W Beijerinek : Leaf extract from a mosaic affected plant can cause disease in healthy plants

W M Stanley : Crystallised virus

Viruses have a genetic material protected in a protein coat called Capsid. Capsid is made up of many sub units called Capsomeres. Capsomeres are arranged in helical or polyhedral geometric forms.

Bacteriophages

AIDS, Mumps, Small pox, Herpes, Influenza

Mosaic formation, Leaf rolling&curling, Yellowing, Vein clearing ,Dwarfing and Stunted growth

Symbiotic association between Algae and Fungi, Pollution indicators

Algal component - Phycobiont

Fungal component - Mycobiont

Algae prepare food for Fungi and Fungi provide shelter and absorb mineral nutrients and water.

A symbiotic association between Fungus and roots of higher plants.

Free infectious RNA, Have no protein coating

Discovered by T O Diener

Disease : Potato spindle tuber disease

Prions are abnormally folded protein similar to the size of viruses.They cause

Spongiform Encephalopathy(BSE) aka Mad cow disease in cattles

Cr-Jacob disease(CJD) in humans