Characteristics of Living Organisms and Biodiversity

Jun 9, 2024

Characteristics of Living Organisms

Segregating Living and Non-Living

  • Certain characteristics distinguish living organisms from non-living matter
  • Characteristics can be definitive or non-definitive

Growth

  • Living organisms (cellular or unicellular) grow via cell division
    • Multicellular organism: cell division increases mass
    • Unicellular organism (e.g., amoeba): cell division results in two new organisms
    • Plants: grow via cell division throughout life
    • Animals: grow up to a certain age; cell division occurs mainly to replace lost cells
  • Non-living objects (e.g., rocks) can grow externally (e.g., sand deposition)
  • Internal vs External Growth: Internal growth is a characteristic of living organisms

Reproduction

  • Unicellular organisms: growth and reproduction lead to an increase in cell number
  • Multicellular organisms: reproduction creates offspring; can be sexual or asexual
    • Sexual: seen in higher organisms (humans, animals)
    • Asexual: seen in lower organisms (e.g., yeast - budding, flatworm - fragmentation)
  • Some organisms (e.g., sterile worker bees) do not reproduce but are still considered living
  • Conclusion: Reproduction is not a definitive characteristic

Metabolism

  • Organisms produce and convert chemicals into biomolecules through metabolic reactions
  • Metabolism occurs in all living organisms
  • In vitro reactions: isolated metabolic reactions are not considered living
  • Conclusion: Metabolism is a definitive feature of living organisms

Cellular Organization

  • Living organisms are made up of cells
  • Not observed in non-living matter
  • Conclusion: Cellular organization is a definitive feature

Consciousness

  • Living organisms sense and respond to environmental stimuli
    • Examples: sunflower facing the Sun, humans wearing woolens in winter
  • Conclusion: Consciousness is a definitive feature

Summary

  • Definitive characteristics of living organisms: Metabolism, Cellular Organization, Consciousness

Biodiversity and Classification

Biodiversity

  • Earth's diversity: millions of species of fungi, plants, animals
  • Every species: group of similar individuals sharing a common gene pool, interbreeding freely
  • Approximately 1.7 to 1.8 million known species

Nomenclature

  • Standardized naming to avoid confusion
  • Identification: knowing the correct description
  • Scientific Naming: Based on principles from ICBN (plants) and ICZN (animals)
    • Example: Ficus religiosa (sacred fig)
    • Binomial nomenclature: Generic name + Specific epithet
    • Devised by Carolus Linnaeus
    • Formatting: Italics in print, underlined when handwritten
    • Capitalization: Genus starts with a capital letter, specific epithet with a lowercase letter

Taxonomy and Classification

  • Classification: grouping based on observable characters
  • Taxa: Groups with specific characteristics (e.g., mango trees, dogs)
  • Systematics: Study of organisms' relationships, including identification, classification, nomenclature, and evolutionary relationships

Taxonomic Categories

  • Classification hierarchy: Kingdom, Phylum/Division, Class, Order, Family, Genus, Species
  • Species: Basic unit, group with fundamental similarities
  • Genus: Group of related species
  • Family: Group of related genera
  • Order: Collection of related families
  • Class: Group of related orders
  • Phylum/Division: Group with common features
  • Kingdom: Largest category; all animals (Animalia), all plants (Plantae)
  • Characteristics decrease in commonality from Species to Kingdom

Importance of Taxonomy

  • Simplifies the study of organisms
  • Tools: Herbariums, Botanical Gardens, Museums, Zoos, Keys
    • Herbarium: Collection of dried plant specimens
    • Botanical Gardens: Cultivated plant collections
    • Museums: Collections of preserved plants and animals
    • Zoos: Wild animals in protected environments
    • Keys: List of questions for identification and classification

Other Taxonomical Aids

  • Flora: Information about plants in a region or period
  • Manuals: Help identify plant and animal species in an area
  • Monographs: Detailed description of a single taxon

Conclusion

  • Taxonomical aids are crucial for studying and conserving biodiversity