Cls 9 Chp 7 Notes

       Class 9 Science Notes      

      Chapter 7 Diversity In Living Organisms   

Introduction

→ All living organism are grouped on the basis of their similarities and increasing complexities into different complexities.

→ Biodiversity means the variety of living organisms present on a particular region.

→ There are about 20 lac organisms known on the earth which differ from one another in external form, internal structure, mode of nutrition, habitat, etc.

• Taxonomy: It is a branch of biology which deals with identification, nomenclature and classification of organisms. Carolus Lannaeus is called the father of taxonomy.

Classification

→ The method of arranging organisms into groups or sets on the basis of similarities and differences is called classification.

Importance of Classification

→ It makes the study of wide variety of organisms easy and in systematic manner.

→ It helps to understand how the different organisms have evolved withtime.

→ It helps to understand the inter-relationships among different groups of organisms.

→ It forms a base for the study of other biological sciences, like biogeography.

Basis of Classification

→ There are certain features or properties used for the classification of living organisms which are known as characteristics.

→ Organisms with same characteristics are placed in same groups.

Classification System

• Two kingdom classification: Carolus Linnaeus in 1758 classified the living organisms into two groups as plants and animals.

• Five kingdom classification: H. Whittaker in 1959 further classified the organisms into five kingdoms as Kingdom Monera, Kingdom Protista, Kingdom Fungi, Kingdom Plantae and Kingdom Animalia.

→ Carl Woese in 1977 further divided Kingdom Monera into archaebacteria (or Archae) and Eubacteria (or Bacteria).

• Hierarchy of Classification: Linnaeus proposed a classification system by arranging organisms into taxonomic groups at different levels according to the characteristics they have.

Groups or Levels from top to bottom

→ The major characteristics considered for classifying all organisms into five major kingdoms.

• Type of cellular organization

(i) Prokaryotic cells: These are primitive and incomplete cells without well-defined nucleus.

(ii) Eukaryotic cells: These are advanced and complete cells with well-defined nucleus.

• Body organization

(i) Unicellular organisms: These are organisms made up of single cell with all activities performed by the single cell.

(ii) Multicellular organisms: These are organisms made up of large number of cells with different functions performed by different cells.

• Mode of obtaining food

(i) Autotrophs: These are the organisms that make their own food by photosynthesis.

(ii) Heterotrophs: These are the organisms which depend on other organisms for food.

Five Kingdom Classification

R. H. Whittaker taxonomist was the first one to propose five kingdom classification.

Monera

(i) Type: Unicellular Prokaryotic

(ii) Mode of nutrition: Autotrophic or heterotrophic

(iii) Body: Lack well-defined nucleus and cell organelles

(iv) Examples: Bacteria, Blue-green algae

Protista

(i) Type: Unicellular Eukaryotic

(ii) Mode of nutrition: Autotrophic or Heterotrophic

(iii) Body: Some organisms use pseudopodia or cilia or flagella for movement

(iv) Examples: Amoeba, Paramecium, Euglena

Fungi

(i) Type: Multicellular Non-green Eukaryotic

(ii) Mode of nutrition: Saprophytic or Parasitic Sometimes symbiotic

(iii) Body: Fungus is made up of long filaments called hyphae. The network of hyphae is mycelium.

(iv) Examples: Yeast, Rhiozpus, Mushrooms moulds

Animalia

(i) Type: Multicellular Eukaryotic

(ii) Mode of nutrition: Heterotrophic

(iii) Body: Exhibits high level of tissue differentiation and have specialized body organs. They have well developed nervous system.

(iv) Examples: Fish, Insects, Animals, Humans, Birds

Kingdom I: Monera

(i) Prokaryotic, unicellular.

(ii) Can be autotrophs or heterotrophs.(iii) May or may not have cell wall.

(iv) Examples: Anabaena and Bacteria (heterotrophic), Cyano-bacteria or Blue-green algae (autotrophic).

Kingdom II: Protista

(i) Eukaryotic, unicellular.

(ii) Can be autotrophic or heterotrophic.

(iii) May have cilia, flagella or pseudophodia for locomotion.

(iv) Examples: Plants like unicellular algae, diatoms; animals like protozoans (Amoeba, Paramecium, Euglena); fungi like slime molds and water molds.

Kingdom III: Fungi

(i) Eukaryotic.

(ii) Mostly multicellular but sometimes unicellular (yeast).

(iii) Source of food:

• Mostly saprophytes: These organisms use decaying material for food.

• Some parasitic: These organisms live inside body of other living organism to have food and can be disease causing.

• Symbiotic relation: These are relations between two organisms in which they live together for benefit of one or both.

→ Lichens are a symbiotic relation between fungi and cyanobacteria.

→ Here fungi gets food from cyanobacteria and in return cyanobacteria gets water and protection from sunlight through fungi.

(iv) Cell wall is made of chitin.

(v) Examples: Mushrooms (Agaricus), green mold (Penicillium), smut (Aspergilus).

Kingdom IV: Plantae

(i) Eukaryotic, multicellular.

(ii) Autotrophs.

(iii) Cell wall present.

Basis of division in Kingdom Plantae

(i) Differentiated body parts: Body is differentiated into leaves, stems, roots, flowers, etc.

(ii) Presence of vascular tissue: There are two types of vascular tissues present in the plants.

• Xylem: Helps in transport of water.

• Phloem: Helps in transport of food.

(iii) Reproduction through seeds or spores:

• Phanerogamae : Plants with seeds are called phanerogamae. They contains embryo with stored food and are multicellular.

• Cryotogamae: Plants with spores are called cryptogamae. They contains only naked embryo and are generally unicellular.

(iv) Seeds are inside the fruit or naked:

• Angiospermae: These are plants with seeds inside the fruit and bears flowers.

• Gymnospermae: These are plants with naked seeds and do not bear flowers.

Division 1: Thallophyta

(i) Basic and elementary plants with undifferentiated body parts.

(ii) Generally called algae.

(iii) No vascular tissue present.

(iv) Reproduce through spores.

(v) Mainly found in water.

(vi) Example: Ulva, Spirogyra, Ulothrix, Cladophora, Chara.

Division 2: Bryophyte

(i) Body structure differentiated but not fully developed.

(ii) No vascular tissues present.

(iii) Reproduce through spores.

(iv) Found on both land and water therefore known as ‘Amphibians of Plantae Kingdom’.

(v) Example : Liverwort (Marchantia, Riccia), Mosses (Funaria), Hornwort (Dendrocerous).