Topics in the Chapter
  • Introduction
  • Classification
  • Five kingdom classification
  • Type of cellular organization
  • Body organization
  • Mode of obtaining food
  • Five kingdom classification
  • Monera
  • Protista
  • Fungi
  • Plantae
  • Animalia
  • Nomenclature
Introduction
  • Biodiversity: Refers to the variety of living organisms in a specific region.
  • Around 20 lakh organisms exist on Earth, each differing in: External form, Internal structure, Mode of nutrition, Habitat
  • Taxonomy: Branch of biology for identification, nomenclature, and classification of organisms.
  • Father of Taxonomy: Carolus Linnaeus
Classification
  • Definition: Arranging organisms into groups based on similarities and differences.
Importance of Classification
  • Simplifies the study of a vast number of organisms.
  • Provides insight into the evolution of different organisms.
  • Helps understand inter-relationships between groups.
  • Forms a basis for studying other biological sciences like biogeography.
Basis of Classification
  • Characteristics: Features or properties used to classify organisms.
  • Organisms sharing similar characteristics are grouped together.
Classification Systems

Two Kingdom Classification

  • Proposed by: Carolus Linnaeus, 1758.
  • Divides organisms into two groups: Plants & Animals

Five Kingdom Classification

  • Proposed by: H. Whittaker, 1959.
Classifies organisms into five kingdoms:
  • Kingdom Monera
  • Kingdom Protista
  • Kingdom Fungi
  • Kingdom Plantae
  • Kingdom Animalia
Further Division by Carl Woese (1977): Split Kingdom Monera into:
  • Archaebacteria (Archae)
  • Eubacteria (Bacteria)

Hierarchy of Classification

  • Concept by: Carolus Linnaeus
  • Structure: Arranges organisms into taxonomic groups at various levels based on characteristics.
Hierarchy of Classification Levels (Top to Bottom)
  1. Kingdom
  2. Phylum
  3. Class
  4. Order
  5. Family
  6. Genus
  7. Species
Criteria for Classifying Organisms into Five Kingdoms 

1. Cellular Organization:

  • Prokaryotic Cells: Primitive, incomplete cells lacking a defined nucleus.
  • Eukaryotic Cells: Advanced, complete cells with a well-defined nucleus.
2. Body Organization:
  • Unicellular: Single-celled organisms; all life functions occur in one cell.
  • Multicellular: Multiple cells with specialized functions.
3. Mode of Nutrition:
  • Autotrophs: Produce their own food via photosynthesis.
  • Heterotrophs: Depend on other organisms for food.
Five Kingdom Classification by R.H. Whittaker

1. Monera

  • Type: Unicellular, Prokaryotic
  • Nutrition: Autotrophic or Heterotrophic
  • Body: Lacks a well-defined nucleus and cell organelles
  • Examples: Bacteria, Blue-green algae
2. Protista
  • Type: Unicellular, Eukaryotic
  • Nutrition: Autotrophic or Heterotrophic
  • Body: Movement via pseudopodia, cilia, or flagella
  • Examples: Amoeba, Paramecium, Euglena
3. Fungi
  • Type: Multicellular, Non-green, Eukaryotic
  • Nutrition: Saprophytic, Parasitic, or Symbiotic
  • Body: Composed of hyphae (filaments); network forms mycelium
  • Examples: Yeast, Rhizopus, Mushrooms, Molds
4. Plantae
  • Type: Multicellular, Eukaryotic
  • Nutrition: Autotrophic
  • Body: Highly specialized tissues and organs
  • Examples: Trees, Plants, Shrubs
5. Animalia
  • Type: Multicellular, Eukaryotic
  • Nutrition: Heterotrophic
  • Body: Highly specialized tissues and organs, well-developed nervous system
  • Examples: Fish, Insects, Animals, Humans, Birds
Kingdom I: Monera

Characteristics:

  • Type: Prokaryotic, unicellular
  • Nutrition: Can be autotrophs or heterotrophs
  • Cell Wall: May or may not have a cell wall

Examples:

  • Heterotrophic: Anabaena, Bacteria
  • Autotrophic: Cyanobacteria (Blue-green algae)
Kingdom II: Protista

Characteristics:

  • Type: Eukaryotic, unicellular
  • Nutrition: Can be autotrophic or heterotrophic
  • Locomotion: May use cilia, flagella, or pseudopodia

Examples:

  • Plants: Unicellular algae, diatoms
  • Animals: Protozoans (Amoeba, Paramecium, Euglena)
  • Fungi-like: Slime molds, water molds
Kingdom III: Fungi

Characteristics:

  • Type: Eukaryotic; mostly multicellular (some unicellular, like yeast)
  • Cell Wall: Composed of chitin

Nutrition:

  • Saprophytes: Feed on decaying matter
  • Parasitic: Live in host organisms, may cause disease
  • Symbiotic: Mutual benefit, as in lichens (symbiosis between fungi and cyanobacteria) Lichens: Fungi provide water and sunlight protection; cyanobacteria provide food

Examples:

  • Mushrooms (Agaricus)
  • Green mold (Penicillium)
  • Smut (Aspergillus)
Kingdom IV: Plantae

Characteristics:

  • Type: Eukaryotic, multicellular
  • Nutrition: Autotrophic
  • Cell Wall: Present

Basis of Division:

  • Differentiated Body Parts: Includes leaves, stems, roots, flowers, etc.
  • Vascular Tissue: Xylem: Transports water & Phloem: Transports food
  • Reproduction: Phanerogamae: Seed-producing plants with multicellular embryos. & Cryptogamae: Spore-producing plants with unicellular, naked embryos.
  • Seed Characteristics: Angiospermae: Seeds inside fruit, flowers present. & Gymnospermae: Naked seeds, no flowers.
Divisions of Plantae

1. Thallophyta

  • Structure: Basic, undifferentiated body (algae)
  • Vascular Tissue: Absent
  • Reproduction: Spores
  • Habitat: Mostly aquatic
  • Examples: Ulva, Spirogyra, Ulothrix, Cladophora, Chara
2. Bryophyta
  • Structure: Partially differentiated
  • Vascular Tissue: Absent
  • Reproduction: Spores
  • Habitat: Found on land and water; known as “Amphibians of Plantae”
  • Examples: Marchantia (Liverwort), Funaria (Moss), Dendrocerous (Hornwort)
3. Pteridophyta
  • Structure: Differentiated body (leaves, stems, roots)
  • Vascular Tissue: Present
  • Reproduction: Spores
  • Examples: Marsilea, Ferns, Horsetails
4. Gymnosperms
  • Structure: Differentiated body parts
  • Vascular Tissue: Present
  • Seeds: Naked, no flowers or fruits
  • Characteristics: Perennial, evergreen, woody
  • Examples: Pine (Deodar), Cycus, Ginkgo
5. Angiosperms
  • Characteristics: Flower-bearing; flowers develop into fruits
  • Seeds: Enclosed within fruit
  • Embryo Structure: Contains cotyledons (seed leaves)

Subdivisions of Angiosperms:

1. Monocots:

  • Seed: One cotyledon
  • Root: Fibrous
  • Stem: False or hollow
  • Leaf Venation: Parallel
  • Flower Petals: In multiples of three
  • Examples: Wheat, Corn, Rice

2. Dicots:

  • Seed: Two cotyledons
  • Root: Prominent primary root
  • Stem: Strong
  • Leaf Venation: Reticulate
  • Flower Petals: In multiples of five
  • Examples: Banyan, Sunflower, Potato, Peanut, Mango
Kingdom V: Animalia

Basis of Classification

1. Symmetry:

  • Bilateral Symmetry: Organism can be divided into mirror-image right and left halves by one vertical plane.
  • Radial Symmetry: Organism arranged equally around a central point, like spokes on a wheel.

2. Germ Layers:

  • Definition: Layers of cells in the embryonic stage that develop into specific body parts.
Types of Germ Layers:
  • Ectoderm: Outermost layer; forms nails, hair, epidermis, etc.
  • Endoderm: Innermost layer; forms stomach, colon, bladder, etc.
  • Mesoderm: Middle layer; forms bones, cartilage, etc.
Types Based on Germ Layers:
  • Diploblastic: Derived from two layers (ecto and endo).
  • Triploblastic: Derived from all three layers (ecto, endo, meso).

3. Coelom:

  • Definition: Body cavity that supports and protects organs, crucial for organ function (e.g., heart expansion).
Types Based on Coelom:
  • Acoelomates: No body cavity; simpler organisms.
  • Coelomates: True cavity fully lined by mesoderm.
    • Schizocoelomates/Protostomes: Coelom forms by mesoderm splitting.
    • Enterocoelomates/Deuterostomes: Coelom forms from endodermal pouches.
  • Pseudocoelomates: False cavity; scattered mesoderm between endoderm and ectoderm.

4. Notochord:

  • Definition: A rod-like structure running along the body between nerve tissue and gut, providing muscle attachment for movement.
Types Based on Notochord:
  • Without Notochord
  • With Notochord
  • Notochord in Embryonic Stage, Vertebral Column in Adult
Phylum 1: Porifera (Sponges)
  • Level of Organization: Cellular
  • Mobility: Non-motile
  • Body Structure: Porous body forming a canal system for circulation of water and food
  • Skeleton: Hard outer layer
  • Examples: Sycon, Spongilla, Euplectelia
Phylum 2: Coelenterata
  • Level of Organization: Tissue
  • Coelom: Absent
  • Symmetry: Radial, diploblastic
  • Body Structure: Hollow gut; capable of movement
  • Examples: Hydra, sea anemone, jellyfish, corals
Phylum 3: Platyhelminthes (Flatworms)
  • Coelom: Absent
  • Symmetry: Bilateral, triploblastic
  • Lifestyle: Free-living or parasitic
  • Digestive System: Single opening for both ingestion and egestion
  • Examples: Planaria (free-living), liver fluke (parasitic)
Phylum 4: Mollusca
  • Coelom: Present
  • Symmetry: Bilateral, triploblastic
  • Body: Soft, sometimes with shell; generally unsegmented
  • Special Features: Muscular foot for movement, kidney-like excretion organ, often with a shell
  • Examples: Chiton, octopus, Pila, Unio
Phylum 5: Annelida
  • Coelom: Present
  • Symmetry: Bilateral, triploblastic
  • Body Structure: Segmented, specialized organ differentiation
  • Habitat: Land or water
  • Examples: Earthworm, leech, Nereis
Phylum 6: Arthropoda
  • Coelom: Present
  • Symmetry: Bilateral, triploblastic
  • Body Structure: Segmented with exoskeleton of chitin, jointed appendages
  • Notable: Largest phylum, covering 80% of species
  • Examples: Prawn, scorpion, cockroach, housefly, butterfly, spider
Phylum 7: Echinodermata
  • Body Structure: Spiny skin, marine habitat, endoskeleton of calcium carbonate
  • Symmetry: Bilateral in larvae, radial in adults
  • Locomotion: Water vascular system
  • Examples: Antedon, sea cucumber, starfish, Echinus
Phylum 8: Protochordata
  • Habitat: Marine
  • Symmetry: Bilateral, triploblastic
  • Key Feature: Notochord for muscle attachment; gills at some life stage
  • Examples: Balanoglossus, Herdmania, Amphioxus
Phylum 9: Nematoda
  • Body: Cylindrical, bilateral, triploblastic
  • Coelom: Pseudocoelom
  • Lifestyle: Parasitic, causes diseases like elephantiasis
  • Examples: Ascaris, Wuchereria
Phylum 10: Vertebrata
  • Key Feature: Notochord transforms into a vertebral column
  • Circulatory System: Heart with 2, 3, or 4 chambers
  • Organs: Kidneys for excretion, paired appendages
  • Examples: Humans (4-chambered heart), frogs (3-chambered), fishes (2-chambered)
Classes within Vertebrata

1. Pisces (Fishes)

  • Habitat: Aquatic, scales/plates on skin, fins for movement
  • Respiration: Gills
  • Circulation: Cold-blooded, 2-chambered heart
  • Reproduction: Lay eggs
  • Skeleton Types: Cartilaginous (e.g., sharks) and bony (e.g., tuna)

2. Amphibia

  • Habitat: Land and water, skin with mucous glands
  • Respiration: Gills or lungs
  • Circulation: Cold-blooded, 3-chambered heart
  • Reproduction: Lay eggs in water
  • Examples: Frogs, toads, salamanders

3. Reptilia

  • Skin: Covered with scales
  • Circulation: Cold-blooded, mostly 3-chambered heart (4 in crocodiles)
  • Respiration: Lungs
  • Reproduction: Lay hard-shelled eggs
  • Examples: Snakes, turtles, crocodiles

4. Aves (Birds)

  • Body Temperature: Warm-blooded
  • Heart: 4 chambers
  • Features: Feathers, wings (forelimbs), eggs with hard shells
  • Examples: Crow, sparrow, ostrich

5. Mammalia (Mammals)

  • Body Temperature: Warm-blooded
  • Heart: 4 chambers
  • Features: Mammary glands, hair, sweat glands
  • Reproduction: Mostly give birth to young (except for egg-laying species like platypus)
  • Examples: Humans, lions, bats, whales

Nomenclature of Organisms

  • Challenge: Organisms may have different names in various languages, leading to confusion.
  • Solution: A universal scientific naming system, known as Binomial Nomenclature, was introduced by Carolus Linnaeus to ensure consistent naming across languages.

Conventions for Writing Scientific Names

1. Order: The scientific name should follow the order of Genus followed by species.
2. Capitalization:
  • The first letter of the Genus should be capitalized.
  • The species name should be in lowercase.
3. Formatting:
  • When printed, the name should appear in italics.
  • When handwritten, both Genus and species should be underlined separately.

Example:

  • Homo sapiens (humans)
  • Panthera tigris (tiger)