Overview
This lecture covers the key features used to classify living organisms into five kingdoms, further subdivisions in animals, plants, and arthropods, and briefly introduces the characteristics of viruses.
Five Kingdom Classification
- Organisms are classified into five kingdoms: Animal, Plant, Fungus, Prokaryote (Bacteria), and Prototist (Protista).
- Animals and plants are always multicellular; fungi are mostly multicellular but some (like yeast) are unicellular.
- Prokaryotes (bacteria) are always unicellular and lack a proper nucleus (no nuclear membrane).
- Prototists are mostly unicellular, some have a cell wall, and have a true nucleus.
- Animals: no cell wall, heterotrophic (consume ready-made food), have membrane-bound organelles.
- Plants: cell walls of cellulose, autotrophic (photosynthesize), contain chloroplasts.
- Fungi: cell walls of chitin, no chloroplasts, heterotrophic (extracellular digestion).
- Prokaryotes: cell walls of peptidoglycan, no true nucleus, have ribosomes, perform extracellular digestion.
Animal Kingdom: Vertebrates
- Vertebrates have a backbone; main groups: Fish, Amphibians, Reptiles, Birds, Mammals.
- Fish: cold-blooded, live in water, breathe through gills, covered in scales, lay eggs.
- Amphibians: cold-blooded, smooth moist skin, live in water and on land, lungs and gills, lay eggs.
- Reptiles: cold-blooded, dry scaly skin, lay eggs, live on land or water, breathe with lungs.
- Birds: warm-blooded, feathers, lightweight bones, beaks, lay eggs, breathe with lungs.
- Mammals: warm-blooded, body covered in hair/fur, give birth to live young (usually), breathe with lungs.
Animal Kingdom: Arthropods
- Main groups: Crustaceans, Myriapods, Insects, Arachnids.
- All have tough exoskeleton, jointed appendages, and segmented bodies.
- Insects: three body parts (head, thorax, abdomen), six legs, usually wings, compound eyes, one pair of antennae.
- Crustaceans: phallothorax and abdomen, more than four pairs of legs, two pairs of antennae, compound eyes, hard shell.
- Myriapods: long segmented bodies, many pairs of legs (one per segment), one pair of antennae, simple eyes.
- Arachnids: head and phallothorax, four pairs of legs, simple eyes, no antennae.
Plant Kingdom
- Two main groups: Ferns (no seeds, reproduce by spores) and Flowering Plants (produce seeds).
- Flowering plants are divided into Monocotyledons (monocots, one seed leaf, parallel veins) and Dicotyledons (dicots, two seed leaves, network veins).
- Ferns have vascular tissue (xylem and phloem) but no flowers or seeds.
Key Terms & Definitions
- Vertebrate — animal with a backbone.
- Exoskeleton — tough external skeleton found in arthropods.
- Autotroph — organism that makes its own food (e.g., plants).
- Heterotroph — organism that consumes other organisms for food.
- Cotyledon — seed leaf in flowering plants.
- Peptidoglycan — material composing bacterial cell walls.
Action Items / Next Steps
- Review and memorize the differences between the five kingdoms.
- Learn the distinguishing features of major vertebrate and arthropod groups.
- Compare monocot and dicot plant characteristics.
- Study the structure and reproduction of ferns and flowering plants.