Diversity In Living Organism Short Notes Class 9 Science Chapter 7

Diversity In Living Organism Short Notes | Class 9

Introduction

  • Diversity is the occurrence of a large number of different organisms in different ecosystems or geographical regions. This diversity is required for a balanced ecosystem.
  • Classification makes it easier to group the enormous number of living organisms in categories based on similarities and differences. This makes it easier to study and understand them.
  • Taxonomy is the science of organism classification. It is the process of categorizing organisms in categories such as kingdom, phylum, class, order, family, genus, and species.

Classification

Classification in terms of diversity in living organisms is the systematic categorization of organisms into groups based on their similarities and differences.

1. Purpose:

  • To make it easier to study a large number of different organisms in a simpler and systematic way.
  • To understand the relationships and evolution of different organisms.

2. Basis of Classification:

  • Cell Structure: Whether the organisms are unicellular or multicellular.
  • Mode of Nutrition: Autotrophic (self-nourishing) or heterotrophic (feeding on others).
  • Reproduction: Sexual or asexual reproduction.
  • Body Organization: Simple or complex body organization.

3. Classification Systems:

  • Two-Kingdom Classification: Suggested by Carolus Linnaeus, categorizing organisms into plants and animals.
  • Five-Kingdom Classification: Suggested by R.H. Whittaker, categorizing organisms into Monera, Protista, Fungi, Plantae, and Animalia

4. Hierarchy of Classification:

  • Kingdom: The most superior level, categorizing organisms based on fundamental characteristics.
  • Phylum: Categorizes organisms within a kingdom based on large body plans.
  • Class: Further categorizes phyla based on more specific characteristics.
  • Order: Categorizes classes into more specific groups.
  • Family: Categorizes orders into smaller groups.
  • Genus: Categorizes species that are closely related.
  • Species: The most specific level, representing individual organisms that can interbreed

5. Five-Kingdom Classification

1. Monera:

  • Unicellular, prokaryotic organisms (e.g., bacteria).
2. Protista:

  • Mainly unicellular, eukaryotic organisms (e.g., amoeba, algae).

3. Fungi:

  • Multicellular, eukaryotic organisms with cell walls composed of chitin (e.g., mushrooms, yeast).

4. Plantae:

  • Multicellular, eukaryotic, autotrophic organisms (e.g., trees, flowers).

5. Animalia:

  • Multicellular, eukaryotic, heterotrophic organisms (mammals, insects, etc.)

Kingdom I : Monera

Kingdom Monera comprises some of the most ancient and primitive living organisms on this planet

  • Prokaryotic Cells: Organisms in this kingdom do not have a true nucleus and membrane-bound organelles1.
  • Unicellular: They are single-celled1.
  • Cell Wall: Most of them have a hard peptidoglycan cell wall1.
  • Reproduction: They reproduce asexually through binary fission or budding.
  • Nutrition: They may be autotrophic (food synthesized by themselves) or heterotrophic (relying on other organisms for food)1.

Kingdom II : Protista

  • Eukaryotic Cells: Organisms possess a true nucleus and membrane-bound organelles.
  • Unicellular: Most of the protists are unicellular, but others are multicellular.
  • Nutrition: They may be autotrophic (e.g., algae) or heterotrophic (e.g., protozoans).
  • Locomotion: Protists move by the action of cilia, flagella, or pseudopodia

Kingdom III : Fungi

  • Eukaryotic Cells: Organisms possess a true nucleus and membrane-bound organelles.
  • Multicellular: Most of the fungi are multicellular, but the yeast is unicellular.
  • Cell Wall: Cell wall consists of chitin, a tough complex sugar.
  • Nutrition: They are heterotrophic and derive their nutrition by absorption of organic matter. They can be saprophytic (feeding on dead organisms) or parasitic (feeding on living hosts).

Kingdom IV : Plantae

  • Eukaryotic Cells: Plants possess a true nucleus and membrane-bound organelles.
  • Multicellular: All the plants are multicellular.
  • Cell Wall: The cell wall consists of cellulose.
  • Autotrophic: The plants synthesize their food by photosynthesis by the aid of chlorophyll.

Basis of Division in Kingdom Plantae

1. Differentiated Body Parts:

  • Plants are divided on the basis of whether their body is differentiated into structures such as leaves, stem, roots, and flowers.

2. Presence of Vascular Tissue:

  • Xylem: Xylem facilitates the transport of water and minerals from the roots to other parts of the plant.
  • Phloem: Phloem carries the food produced in the leaves to other parts of the plant.

3. Reproduction Through Seeds or Spores:

Cryptogamae: Plants with spores. Naked embryo and usually unicellular.

4. Type of Seeds:

  • Angiospermae: Flowering plants with seeds in a fruit and producing flowers.
  • Gymnospermae: Naked-seed plants and do not produce flowers.

Division 1 : Thallophyta

1. Simple Body Structure:

  • Thallophytes possess a simple, undifferentiated body without true roots, stems, or leaves.

2. Aquatic Habitat:

  • Most of the thallophytes inhabit aquatic habitats, freshwater or marine.

3. Autotrophic Nutrition:

  • They possess chlorophyll and photosynthesize to produce their own food.

4. Examples:

  • Examples include Spirogyra, Ulothrix, Cladophora, and Chara.

Division 2:  Bryophyte

1. Non-vascular Plants:

  • Bryophytes do not possess true vascular tissues (xylem and phloem) for water and nutrient conduction1.

2. Simple Body Structure:

  • They possess stem- and leaf-like structures but no true roots. They possess rhizoids in the place of true roots for attachment1.

3. Moist Environments:

  • Bryophytes inhabit moist environments because they need water for reproduction and nutrient absorption1.

4. Reproduction:

  • They possess spore formation and undergo alternation of generations with a prominent gametophyte and an inferior sporophyte1.

5. Examples:

  • Examples include mosses, liverworts, and hornworts.

Division 3: Pteridophyta

1. Differentiated Body Structure:

  • Pteridophytes possess well-differentiated plant bodies with true roots, stems, and leaves.

2. Vascular Tissues:

  • They possess vascular tissues (xylem and phloem) for water and nutrient conduction.

3. Reproduction:

  • Pteridophytes are reproduced by spores but not seeds.

4. Habitat:

  • They inhabit shady and moist habitats.

5. Examples:

  • Examples include ferns, horsetails, and club mosses.

Division 4: Gymnosperms

1. Naked Seeds:

  • Seeds are not enclosed in a fruit; they occur bare on cones or leaves.

2. Vascular Plants:

  • Possess well-developed vascular tissues (xylem and phloem) for conduction.

3. Reproduction:

  • Are reproduced by seeds and do not produce flowers.

4. Adaptations:

  • Possess needle-like leaves and thick cuticles to minimize water loss.

5. Examples:

  • Examples include conifers (pine, spruce), cycads, and ginkgo.

Division 5: Angiosperms

  • Possess well-developed vascular tissues and xylem and phloem for transport.
  • Diverse Forms:
  • Contain a diverse group of plants like trees, shrubs, and herbs.
  • Examples:
  • Common examples are roses, mango trees, and grasses.

Kingdom V : Animalia

Foundation of classification of Animalia kingdom:

<Symmetry>

1. Asymmetrical:

  • Animals lacking any special pattern or symmetry. Example: Sponges.

2. Radial Symmetry:

  • Body parts are arranged round a central axis, and hence there are several planes of symmetry. Examples: Sea anemones, jellyfish.

3. Bilateral Symmetry:

  • Body can be divided into two equal halves along a single plane. Examples: Humans, insects.

<Germ Layers>

1. Diploblastic Animals:

  • Two Germ Layers: These animals possess two conspicuous germ layers: the ectoderm (outer) and the endoderm (inner).
  • Examples: Cnidarians like jellyfish and sea anemones.

2. Triploblastic Animals:

  • Three Germ Layers: These animals possess three germ layers: the ectoderm, mesoderm (middle), and endoderm.
  • Examples: Most animals like humans, insects, and birds.

Functions of Germ Layers

  • Ectoderm: Develops the outer covering of the body, like skin, and the nervous system.
  • Mesoderm: Develops muscles, bones, and the circulatory system.
  • Endoderm: Develops the lining of the digestive tract and other internal organs.

<Coelom>

  1. Definition: The coelom is a body cavity lined entirely by mesodermal tissue. It gives room for the development and suspension of the organs.
Types of Animals Based on Coelom:

  1. Acoelomates: Animals lacking a coelom (flatworms).
  2. Pseudocoelomates: Animals possessing a body cavity not lined fully by mesoderm (roundworms).
  3. Coelomates: Animals possessing a true coelom, lined fully by mesoderm (annelids, mollusks, arthropods, echinoderms, and chordates).

<Notochord>

  • A rod-like flexible structure present in the embryonic state of all chordates.
  • Provides skeletal support.
  • In vertebrates, replaced by vertebral column (spine) during development.
  • Key feature of chordates from non-chordates.

Phylum 1: Porifera or Sponges

  • Cellular level of organization
  • Non-motile animal
  • Holes on body which resulted in a canal system for water and food circulation
  • Hard outer layer known as skeletons
  • Examples: Sycon, spongilla, euplectelia

Phylum 2: Coelenterata

  • Water animals (living in water), primarily marine.
  • Some live in colonies (such as corals), others are solitary (such as sea anemones).
  • Multicellular and diploblastic (two germ layers in the embryo).
  • Differentiation of body design is more marked.
  • The body has a central opening.
  • Tentacles encircle the mouth, helping in movement and sensing the environment.

Phylum 3 : Platyhelminthes

  • Triploblastic (three germ layers)
  • Acoelomate (no true body cavity)
  • Bilaterally symmetrical
  • Soft body with or without cilia
  • Dorsoventrally flattened (like a leaf)
  • Don't have an anus and circulatory system
  • Breathe through body surface by diffusion
  • Organ level of organization
  • Hermaphroditic (male and female organs in a single body)

Phylum 4 : Mollusca

  • Mollusks are extremely diverse.
  • They consist of snails, clams, squids, and octopuses.

Phylum 5 : Annelida

  • Segmented worms
  • Bilaterally symmetrical
  • Coelomate (true body cavity)
  • Closed circulatory system
  • Examples: earthworms and leeches

Phylum 6 : Arthropoda

  • Largest phylum (make up 80% of species)
  • Typically referred to as insects
  • Coelom present
  • Bilateral, triploblastic
  • Segmented, sometimes fused
  • Tough exo-skeleton of chitin
  • Appendage joining like feet, antenna
  • Examples : Prawn, scorpio, cockroach, housefly, butterfly, spider

Phylum 7 : Echinodermata

  • Radial Symmetry: Adults usually have a five-part radial symmetry.
  • Endoskeleton: Composed of calcium carbonate plates.
  • Water Vascular System: Employed for movement, feeding, and respiration.
  • Tube Feet: Assist in locomotion and capturing food.
  • Regeneration: Capability to regenerate lost body parts.
  • No Head: Body is unsegmented and doesn't have a definite head.

Phylum 8 : Protochordata

  • Marine Habitat: They are generally found in marine habitats.
  • Bilateral Symmetry: Their bodies are bilaterally symmetrical.
  • Triploblastic: They possess three germ.
  • Organ System Level: They exhibit an organ system level of organization.

Phylum 9 : Nematoda

  • Body Shape: Cylindrical and elongated.
  • Symmetry: Bilaterally symmetrical.
  • Body Cavity: Pseudocoelomate (having a false body cavity).
  • Habitat: Found in various environments, including soil, water, and as parasites in plants and animals.
  • Examples: Ascaris (intestinal roundworm), Wuchereria (causes elephantiasis).

Phylum 10 : Vertebrata

  • Vertebral Column: Presence of a backbone or spinal column.
  • Symmetry: Bilaterally symmetrical.
  • Body Structure: Triploblastic, coelomic, and segmented.
  • Organ Systems: Well-developed respiratory, excretory, and circulatory systems.
  • Heart: Three or four-chambered heart.
  • Examples: Fish, amphibians, reptiles, birds, and mammals

Pisces (Fishes)

  • Habitat: Found in fresh, marine, and brackish water.
  • Body Shape: Streamlined body covered with scales.
  • Respiration: Use gills to obtain oxygen dissolved in water.
  • Movement: Swim using fins and a muscular tail.
  • Blood: Cold-blooded (poikilothermic).
  • Heart: Two-chambered heart.
  • Reproduction: Lay eggs (oviparous).
  • Examples include various species of fish like salmon, goldfish, and sharks

Amphibia (Amphibians)

  • Habitat: Live both on land and in water.
  • Body Structure: Moist, smooth skin without scales; body divided into head and trunk.
  • Respiration: Breathe through lungs, skin, and gills (in some stages).
  • Heart: Three-chambered heart.
  • Reproduction: Lay eggs in water; undergo metamorphosis from larval to adult stage.
  • Examples: Frogs, toads, salamanders.

Reptilia (Reptiles)

  • Habitat: Mostly terrestrial, found in warmer regions.
  • Body Structure: Dry, scaly skin; body divided into head, neck, trunk, and tail.
  • Respiration: Breathe through lungs.
  • Heart: Three-chambered heart (except crocodiles, which have a four-chambered heart).
  • Reproduction: Lay eggs with tough coverings; fertilization is internal.
  • Examples: Snakes, lizards, turtles, and crocodiles.

Aves (Birds)

  • Habitat: Found in almost all environments, from polar regions to the tropics.
  • Body Structure: Feathers, beaked jaws, and lightweight skeletons.
  • Respiration: Breathe through lungs.
  • Heart: Four-chambered heart.
  • Reproduction: Lay hard-shelled eggs (oviparous).
  • Movement: Most can fly using wings, but some are flightless (e.g., penguins, ostriches).
  • Blood: Warm-blooded (endothermic).
  • Examples include sparrows, eagles, and penguins1

Mammalia (Mammals)

  • Habitat: Exist in diverse habitats, from oceans to forests to deserts.
  • Body Structure: Hair or fur on the body; mammary glands in the female for lactation.
  • Respiration: Breathe with lungs.
  • Heart: Four-chambered heart.
  • Reproduction: Mainly give birth to live young (viviparous), but some exceptions like monotremes (e.g., platypus) which lay eggs.
  • Blood: Warm-blooded (endothermic).
  • Examples: Humans, lions, whales, and bats.

Nomenclature

  • Binomial Nomenclature: Developed by Carl Linnaeus, it gives each organism a two-name system: the genus name (capitalized) and the species name (in lowercase). For example, Homo sapiens for humans.
  • Universal Language: Latin is used for scientific names as it is a "dead" language and does not change with time.
  • Rules and Conventions: Governed by international codes, e.g., the International Code of Zoological Nomenclature (ICZN) for animals and the International Code of Botanical Nomenclature (ICBN) for plants.
  • Hierarchy: Names are part of a hierarchical system of classification, e.g., kingdom, phylum, class, order, family, genus, and species.

Nomenclature avoids confusion and allows for clear communication between scientists worldwide.