DIVERSITY IN THE LIVING WORLD

CLASS - XI

Dr. U.P. Pani

Biology - The term biology is derived from the Greek word bios means ‘life’ and logia means ‘study of’.

Biology is the study of life and living organisms.

Life - Life can be defined as the property or quality of the living organisms that distinguishes from dead or non-living in some functions like:

growth metabolism response to stimuli reproduction

BIOLOGY

CHARACTERISTICS OF LIVING THINGS

1. Growth2.

Reproduction3.

Metabolism4. Response to

stimuli

Growth is an important characteristic feature of living beings.

They increase in mass and number. Non-living objects also grow in mass by

accumulation of material on its surface. Growth in a living being takes place due to

internal processes, i.e. cell division. Plants show continuous growth throughout their

life span, while animals show growth up to a certain age.

GROWTH

All living beings produce their offspring by the process of reproduction.

Reproduction is an important process for continuing the lineage of a species.

REPRODUCTION

Fungi reproduce by asexual spores. Yeast and Hydra by budding. Planaria (flat worms) by regeneration. Unicellular organisms like bacteria, unicellular algae or

Amoeba, reproduction is synonymous with growth, i.e., increase in number of cells.

Reproduction

Sexual Asexual

All living organisms are made of chemicals belonging to various classes, sizes and functions.

The chemicals within a living organism are constantly being made and changed into some other biomolecules.

The sum total of all the chemical reactions occurring in our body is metabolism.

METABOLISM

No non-living object exhibits metabolism.

Metabolism

Anabolism Catabolism

Living organisms respond to their surroundings or environment.

Respond to environmental stimuli could be physical, chemical or biological.

Plants respond to external factors like light, water, temperature, other organisms, pollutants, etc.

Organisms can sense and respond to environmental cues. Photoperiod affects reproduction in seasonal breeders,

both plants and animals. Organisms handle chemicals entering their bodies and

aware of their surroundings. Human being, the only organism, which has self-

consciousness.

Response to External Stimuli

Biodiversity - The diverse form of organisms present on earth is called biodiversity.

 Nomenclature – It is a system of naming of organisms.

There are millions of plants and animals in the world. Plants and animals are known in the local area by

their local names. These local names are vary from place to place,

region to region and within a country also. So, it is impossible for any person to remember the

names of an organism in all the languages. Hence, there is need for a uniform system of

nomenclature of organisms.

DIVERSITY IN THE LIVING WORLD

Identification - Identification is the process of assigning a pre-existing taxon name to an individual organism.

ICBN - International Code for Botanical Nomenclature

ICZN - International Code for Zoological Nomenclature

Bionomial nomenclature is a system of naming species by giving each a name composed of two components, generic name and species name.

Carolous Linnaeus invented the modern system of binomial nomenclature.

BINOMIAL NOMENCLATURE

Carolous Linnaeus

 Biological names are usually written in Latin word and in italics font.

Scientific name usually contains two parts: first word is Genus and second word is Species or specific epithet.

Genus name starts with a Capital letter while species name starts with a small letter.

Biological name is or printed in italics to indicate their Latin origin and underlined, when it is handwritten.

Example: Mangifera indica ( Mango), Homo sapiens ( Human), Oryza sativa (Rice), Triticum aestivum (Wheat)

RULES FOR NOMENCLATURE

Classification – It is the process of grouping of organisms into categories based on easily observable characters.

 Taxon - The scientific term for any unit used in the science of biological classification is called taxon.

Taxonomy - Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups.

Carolus Linnaeus is regarded as the father of taxonomy.

Process of Taxonomy

Characterization

Identification

Classification

Nomenclature

Systematics   The word systematics is derived from the

Latin word ‘systema’ means systematic arrangement of organisms.

 Systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time.

 Linnaeus used Systema Naturae as the title of his publication

TAXONOMIC CATEGORY  Classification involves hierarchy of steps

where each step represents a rank or category.

Various steps of the classification hierarchy are called taxonomic categories.

Each level in the hierarchy represents an increase in organisational complexity.

Species is a group of individuals in which the individuals can interbreed among themselves.

Members of a species have a large number of similar characters.

Example:- Mangifera indica (Mango), Solanum tuberosum (potato) Panthera leo (lion);

SPECIES

A group of closely related species is called genus.

Example – Potato,tomato and brinjal are three different

species but all belong to the genus Solanum. Lion (Panthera leo), leopard (Panthera

pardus) and tiger (Panthera tigris) are members of the genus Panthera.

GENUS

A group of closely related genera is called a family.

Families are characterised on the basis of both vegetative and reproductive features of plant species.

Example :- Three different genera Solanum, Petunia and

Datura are placed in the family Solanaceae. In animals, genus Panthera and genus Felis

belong to the family Felidae.

FAMILY

A group of closely related families is called order.

Order and other higher taxonomic categories are identified based on the aggregates of characters.

Example :– Plant families like Convolvulaceae, Solanaceae

are included in the order Polymoniales. In animals, Felidae and Concidae belong the

order Carnivora.

ORDER

Class is a major category made of one or more related orders that posses certain similar correlated characters.

Example – Class mammalia has a number of orders like

carnivora, rodentia, primata, insectivora, etc. all possess mammary glands, external ears and hair.

 

CLASS

A group of closely related classes is called phylum.

In the Plant Kingdom phylum has been replaced with division.

Example - Pisces, Amphibia, Reptilia, Aves and Mammalia belong to the Phylum Chordata.

PHYLUM

A group of all the related phyla is called the Kingdom.

Example :– The Kingdom Plantae comprises all plants from

various divisions. All heterotrophic organisms which are

eukaryotic and lack a cell wall are kept under Animal Kingdom.

KINGDOM

Kingdom

Phylum or Division

Class

Order

Family

Genus

Species

ORGANISMS WITH THEIR TAXONOMIC CATEGORIES

Common Name

Biological Name

Genus Family Order Class Phylum/Division

Man Homo sapiens

Homo Hominidae

Primate Chordate Mammalia

Housefly Musca domestica

Musca Muscidae Diptera Insecta Arthropoda

Mango Mangifera indica

Mangifera Anacardiaceae

Sapindales

Dicotyledonae

Angiospermae

Wheat Triticum aestivum

Triticum Poaceae Poales Monocotyledonae

Angiospermae

Storehouses of information and specimens which can help in identification and classification of organisms are called taxonomic aids.

Study of various species of plants, animals and other organisms are useful in agriculture, forestry, industry, etc.

These studies are useful to know about our bio-resources and their diversity.

These help in identification, naming, and classification of organisms.

TAXONOMICAL STUDIES

1.  Herbarium Herbarium is the storehouse of plant specimens. Specimens are dried, pressed, and preserved on

sheets. These sheets are arranged systematically

according to the universally accepted system of classification.

Herbarium sheet contains information about date and place of the collection, collector’s name, local and scientific name, family, etc.

It provides quick referral systems in taxonomical studies.

TAXONOMICAL AIDS

2. Botanical gardens  A botanical garden is a place where plants are

grow and displayed for the purposes of research and education.

Each plant contains labels indicating their scientific name and family.

Some famous botanical gardens: Indian Botanical Garden, Calcutta National Botanical Research Institute, Lucknow Garden of Medicinal Plants, North Bengal

University, West Bengal

TAXONOMICAL AIDS

3. Museum Musium is the place of collection of

preserved plant plant and animal specimens for study and reference.

Specimens are preserved in containers or jars in preservative solutions and can be preserved as dry also.

Insects are preserved in insect boxes after collecting, killing, and pinning.

Large animals are stuffed and preserved.

TAXONOMICAL AIDS

4. Zoological parks Zoological park is the place where wild animals

are protected under similar to their natural habitat.

It provides opportunity for studying the behaviour and food habits of the animals.

Some famous Zoo in India: Zoological Park, Mysore Nehru Zoological Park, Hyderabad Trivandrum Zoo Chennai Zoo

TAXONOMICAL AIDS

5. Key  Keys are used for identification of plants and

animals based on similarities and dissimilarities. Keys are analytical in nature and based on

contrasting characters in a pair called couplet. Out of two proposed characters, only one which

is relevant is accepted while the other is rejected. Each statement in a key is called a lead. Separate taxonomic keys are required for each

taxonomic category such as family, genus, order, etc.

TAXONOMICAL AIDS

Flora, manuals, monographs, and catalogues are other taxonomical aids.

They help in correct identification Manuals provide information for identification

of names of various species in a given area. Monograph contain information on any

particular taxon.

Other Taxonomical Aids