DIVERSITY IN LIVING

ORGANISMSCH : 7

DEFINITION CLASSIFICATION

A system of arrangement of organisms into different groups on the basis of their similarities, differences and relationship.

Classification is also known as TAXONOMY.

It is the branch of science which deals with and is defined as Identification, nomenclature and classification of organisms with certain principles.

NEED / IMPORTANCE OF CLASSIFICATION

1. It makes the study of wide variety of organism easy.2. The study of organisms is made easy as learning about an

organism belonging to a specific ‘GROUP’ is easy.3. It also helps to understand the interrelationship among

different organisms.4. Many other biological sciences depend on the correct

knowledge of characteristics of organisms which classification provide. Eg in ecology, forestry, biogeography , applied biology.

Hierarchy of Classification Groups

As classification deals with grouping the organisms ,which are called TAXA {Taxon} , each taxa is given a name and they are arranged in a specific pattern in the flowchart of order/sequence.

The organisms that closely resemble are placed in a taxon and further the taxa related are put together in a larger taxon. There are 7 such taxa.

CLASSIFICATION OF LIVING ORGANISMS

KINGDOM [largest]

PHYLLUM/DIVISIONCLASSORDERFAMILYGENUS SPECIES [smallest]

Aristotle gave the first but crude classification.

Carolus Linnaeus in the 18th century gave the first basis of modern classification. He divided organisms into 2 kingdoms : PLANTAE [ Plant Kingdom] and ANIMALIA [ animal kingdom] because he could see only these .Ernst Haeckel , a german zoologist , further added one more kingdom PROTISTA which included all unicellular organisms.

Robert Whittaker , as more developments in biological sciences happened, found that there were significant differences among organisms of the protista and hence he defined two more kingdoms MONERA , FUNGI.

Thus the 5 kingdom classification by R.H. Whittaker came into existence, which is still the basis of modern classification.

Whittaker based his classification on 4 factors namely :

1. Cellular structure- whether the organism is Prokaryotic or Eukaryotic.

2. Cellular organization- whether the organism is Unicellular or Multicellular. In multicellular organisms what is the level of organization.

3. Mode of source of nutrition- whether the organism is Autotrophic or Heterotrophic.

4. Phylogenetic relationships- phylogeny means evolutionary history of a species.

CAROLUS LINNAEUS

R.H.WHITTAK

ER

Evolution and Classification

Darwin's theory of evolution states that all present – day organisms have originated from the same source and during the course of time have evolved into complex organisms by bringing about variations within it’s body to adapt to the changing environment.

This can be easily seen and studied in the classification because it is an arrangement where phylogeny is considered as one of the main criteria.

Classification and Nomenclature

Nomenclature means to name an organism.Naming an organism is essential to identify it as well as distinguish it from the others.In biology all organisms are given specific scientific names. This is done to avoid any confusion when an interaction is held among people of different vernacular regions.Binomial Nomenclature : It was proposed by Carolus Linnaeus, according to this a scientific name consists of 2 components, first the generic name and second is the specific name.

five kingdom classification

•Monera (bacteria)•Protista•Fungi•Plantae•Animalia

The Monera (Bacteria) Kingdom

Simplest form of life- Unicellular, microscopic

Do not have a nucleus-prokaryotic no chlorophyll - saprophytic or

parasitic.Absorb food These are bacteria and

cyanobacteria which is also referred to as blue green algae

Bacteria can be found anywhere, it can grow in hot or cold places

Bacteria can feed on many different things

The Protista Kingdom Single Celled

All have a nucleus - Eukaryotic

Absorb, ingest, and/or photosynthesize food - Autotrophic and heterotrophic

Examples are: paramecium, amoeba

Amoeba

Paramecium

Eukaryotic Made up of hyphae No root, stem and leaf but

fixed to the substrate No chlorophyll

– Saprophytic or parasitic Reproduce by forming

spores Mushrooms, yeasts,

moulds are all forms of fungi

The Fungi Kingdom

The Plantae Kingdom Second largest group of

living things on earth Eukaryotic , Multicellular Have cell wall Lack mobility Most plants contains

photosynthetic pigments (e.g. chlorophyll) for photosynthesis– Autotrophic

Can be divided into two groups:– Non-flowering plants– Flowering plants

Evolution of plants

Classification of PlantsPlants are divided into the four main

groups based on two major characteristics: presence or absence of vascular tissue and seeds.

Vascular tissue transport substances such as water, minerals and sugars throughout the plant.

Seeds are structures that contain an embryo, stored food and an outer coat.

Thallophyta• Plants that do not have

tubes to carry water up the plant or tubes to carry food made in the leaves down the plant

Aquatic May be unicellular or

multicellular No root, stem or leaf Contain photosynthetic

pigments (e.g. chlorophyll) for photosynthesis

example - Sea weed, diatoms, spirogyra

Bryophyta (Mosses) With simple leaves and

stems No root; with rhizoids for

anchorage and absorption of water

Reproduce by spores No vascular tissues Found in damp area Non-vascular land plants do

not contain any conducting tissues and are often referred to as bryophytes. These plants are small, grow close to the ground and include mosses and liverworts.

Liverworts

Hornworts

Pteridophyta (Ferns) With true roots, stems,

leaves and vascular tissuesSeedless vascular plants

contain vascular tissues but do not produce seeds.

Reproduce by spores. Live in damp places.This group includes

horsetails, ferns and club mosses.

Seed Producing Vascular Plants Spermatophytes

Seeded vascular plants also contain extensive vascular tissue and the majority of species in the plant kingdom are in this group. They have a seeds that contain an embryo, a nutrient supply and a protective outer coat.

Seeded vascular plants are divided into angiosperms and gymnosperms.

GymnospermsReproduction by producing seeds that do

not develop within an enclosed structure– Seeds develop in cones, not enclosed by fruits

⇒ naked seeds Needle-shaped leaves to reduce water loss

Angiosperms Angiosperms are flowering plants

with seeds that develop inside a protective structure.

flowers for reproduction. Seeds are produced inside the

fruit (matured ovary)

Two groups of flowering plants

MonocotyledonsDicotyledons

Cotyledons Two One

Leaf venationNetted (Reticulate) Parallel

Root system Tap root system Fibrous root system