RBSE Class 11 Biology Notes Chapter 2 Biological Classification

These comprehensive RBSE Class 11 Biology Notes Chapter 2 Biological Classification will give a brief overview of all the concepts.

RBSE Class 11 Biology Chapter 2 Notes Biological Classification

→ Biological classification is the scientific ordering of various organisms (i.e., bacteria, fungi, algae, plants and animals) in a hierarchial series of groups on the basis of their morphological evolutionary and other relationships.

→ The main objectives of biological classification are:

• to recognise the basic units of classification namely species and
• to group the species into higher categories on the basis of similarities and relationships.

→ Carolus Linnaeus (1707-1778 AD) developed ‘binomial system’ of nomenclature in his book ‘Species Plantarum’ (1753) and ‘Systema Naturae’ (1758). He divided organisms into Animalia and Plantae.

→ Three kingdom system of classification proposed by Ernst Haeckel (1886). He divided organisms into 3 kingdoms: Protista, Animalia and Plantae.

→ In 1938, Herbert F. Copeland proposed a four kingdom system of classification. He divided organisms into 4 kingdoms: Monera, Protista, Animalia and Plantae.

 

→ R.H. Whittaker (1969) proposed a five kingdom system of classification. The kingdoms defined by him were named Monera, Protista, Fungi, Plantae and Animalia.

• Kingdom Monera: It includes prokaryotes (bacteria and blue green algae). They are autotrophs (i.e., phototrophs or chemotrophs) or heterotrophs (saprotrophs or parasites). They are decomposers, mineralisers and nitrogen fixers.
• Kingdom Protista: It includes unicellular aquatic, phototrophs or heterotrophs. Some slime moulds are decomposers.
• Kingdom Fungi: It includes multicellular heterotrophic moulds, mushrooms, puffballs, rusts, mildew etc. Yeasts are unicellular fungi.
• Kingdom Plantae: It includes multicellular, immobile photosynthetic algae (red, brown and green), liverworts, mosses, ferns, conifers and flowering plants. They are producers in biosphere. Some of them are parasites also.
• Kingdom Animalia: It includes multicellular, mobile holozoic sponges, coelenterates, worms, arthopods, molluscs, echinoderms and ch'ordates. They are main consumers in biosphere.

→ Viruses are ultramicroscopic, non-cellular, highly infectious agents that multiply only intracellularly inside the living host cells without involving growth and division outside the living cells they behave as inert particles. They are highly pathogenic and cause infectious diseases in animals and plants. They are nucleoproteins having one or more nucleic acid molecules either DNA or RNA encased in a coat of protein or lipoprotein.
 
→ Bacteriophages are viruses that infect bacteria. Viroids was discovered by T.O. Diener in 1971 as a new infectious agent that was smaller than viruses and caused potato spindle tuber disease. They do not have protein coat that is found around the viruses and possess RNA having low molecular weight.

→ The most notable diseases caused by prions are bovine spongiform encephalopathy (BSE) commonly known as mad cow disease in cattle and its analogue varient Cr. Jacob disease (CJD) in humans.

→ Lichens are symbiotic associations between algae and fungi. The algae component of lichen is called phycobiont and fungal component as mycobiont which are autotrophic and heterotrophic in nature respectively.

→ Biological classification: Scientific ordering of various organisms in a hierarchial series of groups.

→ Prokaryotic cells: Cells having incipient nucleus.

→ Eukaryotice cells: Cells having membrane bounded nucleus and cell organelles.

→ Autotrophs: Organisms capable to produce own organic food.

→ Heterotrophs: Organisms which are not capable to produce own organic food.

→ Chemotrophs: They are organisms that obtain energy by the oxidation of electron donors in their environments.

→ Saprotrophs: Organisms that feed on organic matter

→ Parasites: A plant or an animal that lives in or another plant or animal and gets its food from it. Parasites sometime cause diseases

→ Phylogenetic relationship: Evolutionary history of an organism.

→ Fossils: The remains or impressions of a prehistoric plants or animals embedded in rocks and preserved in petrified form. ,

→ Tissue: The mass of cells that form the bodies of animals and plants.

→ Monera: Kingdom that includes smallest, the simplest and most plentiful prokaryotes such as archaebacteria, eubacteria, cyanobacteria.

→ Bacteria: They are minute, small, unicellular, microscopic, simple undifferentiated prokaryotes,

→ Glycocalyx: Jelly like covering present around the all wall. When it is dense is called capsule and when loosely arranged is called slimelayer.

→ Halophiles: Salt loving bacteria (Archae). 

→ Peptidoglycon: Compound found in bacterial cell wall.

→ Cocci: Spherical, ellipsoidal or ovoid bacteria.

→ Bacillus: Straight, rodshaped or cylindrical bacteria.

→ Spirillum: Spiral or coiled bacteria.

→ Vibrio: Single curved rod shaped bacteria. Thermoacidophiles: Bacteria live in hot and acidic habitats.,

→ Methanogens: Bacteria live anerobically in swamps, marshes and the guts of animals such as—cows and buffaloes and they are responsible for the production of methane (biogas) from the dung of these animals.

→ Eubacteria: True bacteria found in environment possess rigid cellwall and if they motile have a flagellum.

→ Actinomycetes: Unicellular, branched, filamentous bacteria which resemble fungal mycelia.

→ PPLO: Pleuropneumonia like organisms (mycoplasmas). They are smallest organisms.

→ Monera: Kingdom that includes all unicellular eukaryotic microorganism except unicellular algae such as Chlamydomonas, Chlorella etc., fungi e.g., yeasts etc.

→ Chrysophytes: They are diatoms and golden algae (desmids).

→ Frustules: The cells of diatoms are termed as frustules.

→ Diatomaceous earth or diatomite: Cellwall depositions of diatoms.

→ Dinoflagellates: Flagellated, marine photosynthetic organisms.

→ TKeca or lorica: Cellwall of dinoflagellates made of cellulose plates.

→ Euglenoids: Organisms having a mixture of animal and plant characteristics.

→ Slime moulds: Organisms exhibit the characters of both animals and fungi.

→ Protozoans: First formed animals.

→ Planktons: Passively floating organisms on the surface of fresh water/sea.

→ Phytoplankton: Passively floating plants on the water surface.

→ Zooplanktons: Passively floating "animals on the water surface.

→ Fungi: Non-chlorophyllus hetertrophic organisms.

→ Mycology: Branch of science which deals with the study of fungi.
 
→ Caprophilous fungi: Fungi growing on dung.

→ Coenocytic condition: Aseptate mycelium having many nuclei.

→ Prosenchyma: Loosely woven hyphae of fungi.

→ Pseudoparenchyma: Compactly woven fungal hyphae.

→ Plasmogamy: Fusion of protoplasms between two motile or non-motile gametes.

→ Karyogamy: Fusion of two nuclei.

→ Conidia or conidiospores: Spores produced exogeneously mostly in chains from the tips and sides of hyphae.

→ Ascus: Fruiting body of ascomycetes. '

→ Basidiocarp: Large fruiting body of basidiomycetes.

→ Deuteromycetes: Fungi imperfecti having only asexual vegetative phase.

→ Sporodochia: It is a small, compact stroma (mass of hyphae) usually formed on host plants parasitised by mitosporic fungi. ,

→ Pycnidium: It is an asexual fruiting body produced by mitosporic fungi.

→ Acervuli: It is a small asexual fruiting body that erupts through the epidermis of host plants parasitised by microscopic fungi.

→ Plantae: Kingdom that includes all eukaryotic chlorophyll containing organisms which are commonly c&lled plants,

→ Animalia: Kingdom that includes heterotrophic eukaryotic organisms that are multicellular without cell walls and chlorophyll.

→ Viruses: They are ultramicroscopic, non-cellular, highly infectious agents that multiply only intracellularly inside the living host cells without involving growth and division outside the living cells they behave as inert particles.

→ Peplomeres: The smaller subunits of virul envelope are called peplomeres.

→ Bacteriophages: Viruses that infect the bacteria are called bacteriophages.

→ Viroids: Viruses lacking protein are called viroids.

→ Prion: Infectious particles made of only protein.

→ Lichens: Symbiotic associations between algae and fungi.

→ Phycobiont: Algal component of lichen.

→ Mycobiont: Fungal component of lichen.

→ Saxcoles: The lichens which grow on stones are called saxcoles.

→ Corticoles: The lichens which grow on barks of trees are called corticoles.