Diversity in Living Organisms / Life Around You : Summary / Introduction

• Taxonomy  is the branch of biology for the study of classification of organisms following certain rules or principals.
• Systematics (systema – order) – The camparative study of organisms on the basis of morphology, anatomy, ecology, physiology, biochemistry etc. is known as systematics.
• Systematics have three fields (i) Nomenclature (ii) Classification (iii) Taxonomy
• Classification – grouping of organisms, (plants or animals) in different ranks on the basis of their characters is known as classification.
• Father of taxonomy – Carolus Linnaeus.
• Five kingdom system – given by Whittaker (1959)

1. Kingdom monera:

(a) Prokaryotic cells lack defined nucleus or organelles (plastids, mitochondria and advanced (9+2) strand flagella). Autotrophic or heterotrophic.

(b) Reproduction is asexual by fission or budding.

E.g. Blue green algae, Bacteria etc.

2. Kingdom Protista:

(a) They are unicellular or colonial eukaryotic cells.

(b) Reproduction is asexual and sexual.

E.g. Unicellular Algae, Diatoms etc.

3. Kingdom Fungi:

(a) Multinucleate organisms with eukaryotic nuclei. Multicellular with cell wall.

(b) Plastids and photosynthetic pigments lacking. Saprophytes or symbiotic.

(c) Reproduction asexual and sexual both.

E.g. Fungi, yeast, mushrooms

4. Kingdom plantae:

(a) Multicellular organisms with cellulose wall and frequently vacuolated, eukaryotic cells.

(b) Nutritive mode is photosynthetic but absorptive.

(c) Reproduction is sexual.

E.g. Rhodophyta, Phaeophyta, Chlorophyta, Bryophyta, Tracheophyta, Pteridophyta, Gymnosperms, Angiosperms.)

5. Kingdom Animalia:

( a) Multicellular organisms, eukaryotic cell devoid of cell wall.

(b) Lack plastids and photosynthetic pigments.

(c) Organization and tissue differentiation complex

(d) Reproduction is sexual.

• The five kingdoms are further classified into sub groups as –
  Kingdom    →        Phylum for animals / Division for plants          →      Class     →      Order    →    Family      →      Genus     →      Species

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Classification of Plants

 

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Classification of Animals

 

• The whole animal kingdom is divided into two main groups. They are Vertebrates and Invertebrates.
• Animals with backbone are called vertebrates. They are found in land, oceans, rivers, forests, mountains and even in deserts. This group can be further divided into smaller groups by their characteristics. They are fish, amphibians, reptiles, birds, and mammals.
•  Animals that lack the backbone are called invertebrates.
• There are 10 major phyla in the animal kingdom from Protozoa to Chordata. Of these, phylum Protozoa is now placed in the kingdom Protista.

The remaining nine phyla include true multicellular animals. Of these, nearly 95% represent the invertebrates and about 5% represent the vertebrates. The most important features of these major animal phyla, their classification and examples are as follows-

Life on Earth is incredibly diverse. Take a walk in a garden, and you will find different types of trees and plants (flora), birds, insects, animals and may be fish, frog in a stream (fauna). We know, All these organisms are living, but even they are all very different from one another w.r.t. their appearance and mode of life, and maintain their ‘own identity’. The enormous variety of organisms is termed as ‘Bio-Diversity’ (bios – life + diversity – variety). With such a great number of organisms – both living and extinct, it becomes impossible to study every one of them at individual level. This task of studying the diversity of living organisms can be made easier and more effective if the various organisms are arranged in an orderly manner.

 

How do scientists organize this variety into categories they can understand?

They do it by arranging organisms into groups and subgroups. Grouping of organism according to similarities and differences is termed as classification.

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Classification of living organisms