The Living World

• Characteristics of Living Organisms

  • Growth
    • Increase in mass and number
    • Intrinsic (from inside)
    • Defining feature? No (non-living objects also grow by accumulation)
  • Reproduction
    • Progeny formation
    • Sexual and asexual
    • Defining feature? No (mules, sterile worker bees do not reproduce)
  • Metabolism
    • Sum total of all chemical reactions
    • Intracellular and cell-free systems
    • Defining feature? Yes (no non-living object exhibits metabolism)
  • Cellular Organization
    • Made of one or more cells
    • Defining feature? Yes
  • Consciousness
    • Sense surroundings and respond to environmental stimuli
    • Defining feature? Yes (applies even to brain-dead humans in coma)

• Diversity in the Living World

  • Biodiversity
    • Number and types of organisms present on Earth (1.7 - 1.8 million)
  • Nomenclature
    • Providing standardized names to organisms
    • ICBN: International Code for Botanical Nomenclature
    • ICZN: International Code for Zoological Nomenclature
    • Binomial Nomenclature
      • Proposed by Carolus Linnaeus
      • Two components: Genus (Generic name) and Specific epithet (Species)
      • Universal Rules
        • Italics when printed; underlined when handwritten
        • Genus starts with a capital letter; species with a small letter
        • Name of author cited at the end (e.g., Mangifera indica L.)
  • Identification
    • Recognizing correct description of an organism
  • Classification
    • Grouping organisms into categories based on observable characters
    • Taxonomy: Study of characterization, identification, nomenclature, and classification

• Taxonomic Categories

  • Taxonomic Hierarchy
    • Descending arrangement of categories
    • Species -> Genus -> Family -> Order -> Class -> Phylum/Division -> Kingdom
  • Key Categories Explained
    • Species: Group of individual organisms with fundamental similarities (lowest category)
    • Genus: Aggregates of closely related species
    • Family: Group of related genera with less similarity than species/genus
    • Order: Assemblage of families exhibiting a few similar characters
    • Class: Includes related orders
    • Phylum (Animals) / Division (Plants): Classes with a few common features
    • Kingdom: Highest taxonomic category containing all related phyla/divisions

• Taxonomical Aids

  • Herbarium
    • Storehouse of collected plant specimens that are dried, pressed, and preserved on sheets
    • Labeled with date, place of collection, English/local/botanical names, family, collector's name
  • Botanical Gardens
    • Collections of living plants for reference and identification
    • Famous examples: Royal Botanical Garden (Kew, England), Indian Botanical Garden (Howrah, NBRI Lucknow)
  • Museum
    • Collections of preserved plant and animal specimens for study and reference
    • Specimens preserved in jars, insect boxes, or stuffed (larger animals)
  • Zoological Parks (Zoos)
    • Places where wild animals are kept in protected environments under human care
    • Helps learn about food habits and behavior
  • Key
    • Taxonomical aid based on contrasting characters (couplet)
    • Each statement in the key is called a lead
    • Analytical in nature