Diversity in Living Organisms

Category : Banking

 

Introduction

 

  • Biodiversity refers number and types of wide variety of plants and animals present on earth.
  • In 1773, Swedish botanist Carolus Linnaeus formulated the system of Binomial Nomenclature in his book 'Species plantarum''. In binomial system, each name is expressed in two parts i.e., generic name and specific name.
  • Taxon is the branch of biology that deals with the framing of laws and principles for classifying the organisms on the basis of their characteristics and evolutionary relationships.
  • The hierarchial system of classification was introduced by

Kingdom \[\to \] Phylum or Division\[\to \] Class\[\to \] Order\[\to \]Family\[\to \] Genus\[\to \]Species

  • Species is defined as "the smallest real basic unit of taxonomy which is reproductively isolated from other group of individuals".
  • Genus is a group of closely related species that are alike in broad features of their organization.
  • Family is a group of related genera having several common characters.
  • Generally, Order and other higher taxonomic categories are identified based on the aggregates of characters.
  • A Class is made of one or more related orders.
  • The term Phylum is used for animals while Division is commonly employed for plants.
  • Kingdom is the highest taxonomic category. All plants are included in Kingdom Plantae. All animals are included in Kingdom Animalia.
  • Herbarium is a collection of pressed and dried plant specimens that are preserved on paper sheets.
  • In Botanical garden, various plants groups are grown for scientific study, conservation, public education, aesthetics, and recreation. The famous botanical gardens are at Kew (England), Indian Botanical Garden, Howrah (India) and
  • National Botanical Research Institute, Lucknow (India).
  • Museum is a building used for the preservation, storage and exhibition of inanimate objects.
  • Zoological park or zoological garden or zoo is a place where wild animals are kept in protected environment under human care. These animals are kept for public exhibition.

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History of Classification

  • Biological classification was first proposed by Aristotle who used simple morphological characters to classify plants and animals.
  • Linnaeus initially separated plants and animals in two Kingdoms i.e., Kingdom Plantae and Kingdom Animalia.
  • Most accepted System of classification is five system classification which was given by Whittaker.

 

  • Basic Feature of Whittaker’s Five Kingdoms
 

Kingdom

Cellular Organization

Movement

Nutrition

Reproduction

1.

Monera (All Prokaryotes)

Unicellular, without nucleus or membranous organelle.

By flagella (tubulin- dynein system)

Absorptive or photosynthetic

Asexual

2.

Protista (Protozoans, unicellular algae)

Unicellular, eukaryote with nucleus and membranous organelles.

By flagella, cillia, pseudopodia and mucilage propulsion

Absorptive, photosynthetic & holozoic

Both sexual and asexual

3.

Fungi (Multicellular decomposers)

Multicellular eukaryote coenocytic, no plastids, cells wall of cellulose, chitin.

Non-motile

Heterotrophic (saprophytic/ parasitic)

Asexual and sexual both

4.

Plantae (All plants)

Multicellular, higher organisation eukaryotes, cellulosic cell wall, plastids present.

Non-motile

Autotrophic or photosynthetic

Asexual and sexual both

5.

Animalia (All animals)

Multicellular, higher organization, eukaryotes without cell wall and chlorophyll.

Highly motile with all type of motile machinery

Heterotrophic (holozoic or sap ro zoic)

Both sexual and asexual but in higher forms only sexual

 

  • Types of Classification
  • Artificial classification system: It was used by Linneaus. The artificial classification system was based on vegetative characters or on the androecium structure.
  • Natural classification system: It was based on natural affinities among organisms. Both external and internal features were taken into account. It was used by George Bentham and Joseph Dalton Hooker.
  • Phylogenetic classification system: This system of classification is based upon evolutionary relationship and uses morphological characters, origin and evolution of the different organisms. It was proposed by Hutchinson.

 

  • Viruses
  • The term 'virus’ has been derived from latin, which means poison or venom or viscous fluid. They are obligate parasites, i.e., can live inside living host only. They have either RNA or DNA. They have character of both living and non-living.

 

Plant Kingdom

  • Plant Kingdom

 

TABLE: Divisions of Algae and their Main Characteristics

Classes Name

Common

Major Pigments Food

Stored

Cell Wall

Flagellar Number and Position of Insertions

Habitat

Chlorophyceae

Green algae

Chlorophyll a, b

Starch

Cellulose

2-8, equal, apical

Freshwater, brackish and salt water.

Phaeophyceae

Brown algae

Chlorophyll a, c, fucoxanthin

Mannitol, laminarin

Cellulose and algin

2, unequal, lateral

Freshwater (rare), brackish water, salt water

Rhodophyceae

Red algae

Chlorophyll a, d, phycoerythrin

Floridean starch

Cellulose

Absent

Fresh water (some), brackish water, salt water (most)

 

  • Bryophytes
  • Bryophytes are also called amphibians of the plant kingdom because these plants can live in soil but are dependent on water for sexual reproduction. They usually occur in damp, humid and shaded localities.
  • Species of Sphagnum, a moss, provide peat that have long been used as fuel, and because of their capacity to hold water as packing material for trans-shipment of living material.

 

  • Pteridophytes
  • Evolutionarily, they are the first terrestrial plants to possess vascular tissues - xylem and phloem.
  • The main plant body is a sporophyte which is differentiated into true root, stem and leaves. These organs possess well-differentiated vascular tissues. Examples are Psilotum, Equisetum, Dryopteris, Marsilea, etc.

 

  • Gymnosperms
  • Gymnosperms are plants which bear naked seeds i.e., the ovules and the seeds that develop from these ovules after fertilization are not enclosed in fruit wall.
  • Roots in some genera have fungal association in the form of mycorrhiza (Pinus), while in some other (Cycas) small specialized roots called coralloid roots are associated with \[{{N}_{2}}\] fixing cyanobacteria.

 

  • Angiosperms (Flowering Plants)
  • Angiosperms are seed bearing, flowering vascular plants in which seeds are enclosed in fruits.
  • The flower is the most characteristic structure of the angiosperms. The male sex organ in a flower is the stamen. Each stamen consists of a slender filament with an anther at the tip. The anthers, following meiosis, produce pollen grains.
  • The female sex organ in a flower is the pistil or the carpel. Pistil consists of an ovary enclosing one to many ovules. Within ovules are present highly reduced female gametophytes termed embryo sacs. Each embryo-sac has a seven-celled egg apparatus - one egg cell-and two synergids, three antipodal cells and two polar nuclei the polar nuclei eventually fuse to produce a diploid secondary nucleus.
  • Pollen grain, after dispersal from the anthers, are carried by wind or various other agencies to the stigma of a pistil. This is termed as pollination.
  • The pollen tubes enter the embryo-sac where two male gametes are discharged. One of the male gametes fuses with the egg cell to form a zygote (syngamy). The other male gamete fuses with the diploid secondary nucleus to produce the triploid primary endosperm nucleus (PEN). Because of the involvement of two fusions, this event is termed as double fertilisation, and event unique to angiosperms.

 

Animal Kingdom

 

Animals are the most diverse groups of organisms. Multicellular, heterotrophs characterised by mobility, sensory and nervous systems.

  • Phylum - Porifera
  • Sponges are aquatic, mostly marine, solitary or colonial and sessile.
  • Examples of some sponges are: Sycon (scypha), Spongilla (fresh water sponge) and Euspongia (bath sponge).

 

  • Phylum-Coelenterata (Cnidaria)
  • All are aquatic and are mostly marine (exception-Hydra are found in fresh-water), solitary or colonial, sessile, or free-swimming and radially symmetrical animals.
  • Example-Physalia (Portuguese man of war), Adamsia (Sea anemone), Pennatula (Sea-pen), Gorgonia (Sea-fan) and Meandrina (Brain coral).

 

  • Phylum-Ctenophora
  • These are diploblastic, radial symmetrical animals with tissue level of organization.
  • Examples-Hormiphora (sea walnut), Pleurobranchia (sea gooseberry). Cesium (venus girdle), Beroe.

 

  • Phylum-Platyhelminthes
  • These are mostly endoparasites, bilateral symmetrical, triploblastic and acoelomate animals with organ level of organisation.
  • Examples- Taenia (Tape worm), Fasciola (liver fluke).

 

  • Phylum-Aschelminthes
  • They may be free-living, aquatic and terrestrial or parasitic in plants and animals.
  • Examples: Ascaris (Round worm), Wuchereria (filarial worm), Ancylostoma (Hook worm), Enterobius (Pin worm).

 

  • Phylum -Annelida
  • It is characterised by metameric segmentation forming ring like segments.
  • Example: Neries, Pheretima (Earthworm) and Himdinaria (Bloodsucking leech).

 

  • Phylum-Artbropoda
  • They are bilateral symmetry, triploblastic animals, which have organ-system level of organisation.
  • Example: Apis (Honey bee), Bombyx (Silkworm), Laccifer (Lac insect).

 

  • Phylum-Mollusca
  • They are aquatic (marine or fresh water), or terrestrial having an organ-system level of organisation,
  • Pila, Octopus (devil fish), Loligo (sea squid).

 

  • Phylurn - Echinodermata
  • All existing echinoderms are marine, generally live at sea bottom.
  • Asterias (star fish), Cucumaria (commonly called as sea cucumber), Antedon (water lily or feather star).

 

  • Phylum-Hemichordata
  • They are bilaterally symmetrical, triploblastic, and entrocoelous animals.
  • Balanoglossus (acorn worm or tongue worm), Saccoglossus.

 

  • Phylum-Chordata
  • The fundamental four characters of phylum chordata are presence of notochord, a dorsal hollow nerve cord, paired pharyngeal gill slits and post anal tail either in the embryonic or adult stage.
  • Examples: Herdmania (sea squirt), Branchiostoma.

 

  • Subphylum 1 vertebrata is divided into two sections:
  • Section 1 Agnatha (The lawless vertebrates)

Class: Cyclostomata

  • Mouth jawless suctorial and round.
  • All living members are ectoparasites on some fishes. Ex. Petromyzon (lamprey), Myxine (hag fish).

 

  • Section 2 Gnathostomata (The jawed vertebrates)
  1. Superclass: Pisces (Bear fins)

Class: Chondrichthyes

  • They have a cartilagenous skeleton.
  • Some of them possess electric organs e.g. Torpedo.
  • Examples: Scoliodon (Dog fish), Trygon (Sting ray).

Class: Osteichthyes

  • They have a bony skeleton.
  • Examples: Marine - Exocoetus (Flying fish). Hippocampus (Sea horse), Lophius (Angler fish), Fresh water fishes Labeo (Rohu), Catla (Katia).

 

  1. Superclass: Tetrapoda (Bear Limbs)

Class: Amphibia

  • Adapted for both water and land life.
  • They are oviparous and development indirect through distinct larval stage called tadpole. Exambles: Bufo (Toad), Rana (Frog), Hyla (Tree frog), Salamandra (Salamander), Ichthyophis (Limbless amphibia).

Class: Reptilia

  • The class name refers to their creeping or crawling mode of locomotion.
  • They are oviparous; Development direct. Examples: Crocodilus (Crocodile), Bangarus (Krait)

Class: Aves

  • Birds are bipedal feathered animals.
  • Endoskeleton is fully ossified (bony) and the long bones are hollow with air cavities (pneumatic). Examples: Corvus (crow), Pavo (Peacock).

Class: Mammalia

  • These are warm blooded (homiothermous) animals having hair and mammary glands.
  • They are viviparous with few exceptions and development is direct. Example: Oviparous - Tachyglossus = Echidna (spiny Anteater). Viviparous - Pteropus (Flying fox), Camelus (Camel), Macaca (Monkey).

 

Plant Morphology

 

  • The Root
  • It is the underground system, usually below the soil and originates from the radicle.
  • The primary functions of root are fixation of plant firmly on soil, absorption of water and conduction of mineral nutrients.
  • Modified Tap Roots
  • Fusiform: e.g. radish.
  • Napiform: e.g. sugar beet.
  • Conical: e.g. carrot.
  • Tuberous root: e.g. tapioca.
  • Nodulated: e.g. Rhizobium.

 

  • Modified Branched Root

Pneumatophores: Pneumatophores or respiratory roots are short, vertical and negatively geotropic (grow in an upward direction) that occur in certain halophytes, which grow in saline marshes (mangroves), e.g. Rhizophora.

 

  • Modified for Mechanical Functions
  • Prop root: e.g. banyan.
  • Stilt root: e.g. screwpine.
  • Climbing root: e.g. betel.
  • Clinging root: e.g. orchid.
  • Floating root: e.g., Jussiaea.
  • Contractile root: e.g., onion.
  • Root thorn: e.g., coconut.

 

  • Modified Adventitious Root Modified for Physiological Functions
  • Parasitic root: e.g., Cuscuta.
  • Epiphytic root: e.g., Orchids.
  • Tuberous root: e.g., sweet potato.

 

  • Shoot System
  • It is negatively geotropic and positively phototropic.
  • Stem facilitates conduction of water, mineral and food material. It also produces and supports leaves and reproductive structure.

 

  • Modified Stems Underground
  • Tuber: e.g., potato.
  • Bulb: e.g., onion.
  • Rhizome: e.g., ginger.
  • Corm: e.g., Amorphophallus.

 

  • Sub-aerial
  • Runner: e.g. Oxalis.
  • Offset: e.g. Pistia.
  • Stolen: e.g. Mentha.
  • Sucker: e.g. Chrysanthemum.

 

  • Aerial or Metamorphosed
  • Thorn: e.g. Duranta.
  • Stem-tendril: e.g. grape.
  • Phylloclade: e.g. Opuntia.

 

Leaf

 

  • Leaf

            The leaf is a specialised organ of photosynthesis, transpiration and gaseous exchange.

 

  • Venation

            Venation is the arrangement of the veins and the veinlets in a leaf.

  • Reticulate Venation: The veins are arranged in a net like manner, e.g., dicots.
  • Parallel Venation: Here the veins are arranged parallel to each other, e.g., monocots.

           

           

 

  • Inflorescence
  • An inflorescence is the mode of arrangement of flowers on peduncle or mother axis.

 

 

           

 

  • Fruit = Ripened Ovary

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