Characteristics of Living Organisms and Classification

Characteristics of Living Organisms

  • Movement: Ability to move all or part of themselves.
  • Respiration: Chemical reactions breaking down nutrients to release energy.
  • Sensitivity: Detecting and responding to environmental changes.
  • Growth: Permanent increase in size (dry mass, cell size, or cell number).
  • Reproduction: Creating more organisms of their kind.
  • Excretion: Removal of waste products from metabolic reactions.
  • Nutrition: Taking in materials for development, energy, growth and repair.

Classification Systems

  • Classification groups species by shared features.
  • Same species can reproduce to produce fertile offspring.
  • Binomial Naming System: Internationally agreed system with two parts (genus and species).
    • Example: Homo sapiens (humans).
  • Organisms are classified by evolutionary relationships, found via:
    • Physical characteristics.
    • DNA base sequences.
  • DNA studies are more accurate than comparing physical characteristics.
  • Proteins can be studied to find evolutionary relationships, as DNA codes for the amino acid sequence in proteins

Features of Organisms

  • Five Kingdoms: Animal, Plant, Fungus, Prokaryote, Protoctist.
  • Cell features help categorize organisms into kingdoms.
  • Animal cells lack a cell wall and chlorophyll, while plant cells have both.
  • Features of cells:
    • Cytoplasm: Jelly-like material where reactions occur, containing organelles.
    • Cell membrane: Controls entry and exit of substances.
    • DNA: Genetic material in the nucleus.
    • Ribosomes: Site of protein synthesis.
    • Enzymes: Catalyze reactions like respiration.
  • Animal Kingdom: Vertebrates (backbone) and Arthropods (exoskeleton, segmented body).
    • Vertebrates: mammals, birds, reptiles, amphibians, fish.
    • Arthropods: myriapods, insects, arachnids, crustaceans.
  • Plant Kingdom: Flowering and non-flowering plants.
    • Flowering: dicotyledons and monocotyledons.
    • Non-flowering: ferns (reproduce through spores).
  • Viruses are non-cellular and non-living; they do not have characteristics of living organisms
    • Composed of genetic material and protein cost