FIVE KINGDOMS
Definition of species (basic unit of classification):
- Members of a species are similar (phenotype) to each other but different from other species
- Similarity of organisms in same species can be
- physical (branching pattern of trees)
- biochemical (haemoglobin structure)
- immunological (antibody against an antigen equally effective)
- development (similar growth of embryos)
- ecological (occupy identical ecological niche)
- Similarity of organisms in same species can be
- (Group of) organisms able to interbreed/reproduce giving fertile offspring
- Each species is reproductively isolated from every other species
The five-kingdom classification of organisms;
- Nomenclature: Naming of organisms
- Binomial: Biological name of an organism → Genus species
- Taxon: Set of organisms within a category / Taxonomy / Study of biological classification
- Different levels of taxons: SPECIES, GENUS, FAMILY, ORDER, CLASS, PHYLUM, KINGDOM
- Most number of species on right
- Most similar organisms on left
- Unicellular: Single cell; Colonial: Groups of cells; Multicellular: Many cells
- Autotrophs produce energy from inorganic sources
- Phototrophs from photosynthesis/sunlight
- Chemotrophs from simple inorganic (oxidative) processes
- Heterotrophs digest and absorb organic molecules
Prokaryotae (prokaryotes);
- Cell structure:
- Prokaryotes, unicellular
- Prokaryotes lack cytoplasmic organelles found in eukaryotes
- Cell wall: murein
- Nutrition: autotrophic (photosynthesis, chemosynthesis), aerobic heterotrophs
- Divide by binary fission, not by mitosis
- ≈10μm in size (bacterial cell, filaments of blue-green bacteria)
- Mutualistic nitrogen-fixing bacteria live in nodules on the root of legumes / symbiotic
Protoctista (protoctists);
- Cell structure: eukaryotes, unicellular and multicellular
- Cell wall: (sometimes) polysaccharide
- Nutrition: autotrophic, heterotrophic
- Placed in this category by exclusion / cannot be placed in any other kingdom
- Slime moulds / fungi characteristics
- Protozoa / heterotrophic and ingest food
- Algae / photosynthesis
- ≈10μm (amoeba) - 1m (Laminaria / large brown alga)
Fungi;
- Cell structure: eukaryotes, multicellular and unicellular (yeast)
- Cell wall: chitin
- Nutrition: heterotrophic / saprotrophic decomposers or parasitic
- Genus Penicillium
- Body of a fungus is composed of thin filaments called hyphae / form a mycelium
- Secret enzymes / external digestion / absorbs resulting nutrients
- Erect hyphae that grow upwards from the mycelium carry their reproductive spores
- Chains of spores on the erect hyphae / coloured mould visible on stored food
- Break down organic matter
Plantae (plants);
- Cell structure: only multicellular, eukaryotic; large vacuoles
- Cell wall: cellulose
- Nutrition: autotrophic (photosynthetic)
- Growth is restricted to meristems (layers/patches of dividing cells)
- Non-motile; adapted to land / strong tissues, leave gas exchange system, waterproofed
- Eg mosses, ferns, conifers, angiosperms (flowering plants)
Plant kingdom has two different types of adults in their life cycle;
- Gametophytes, hidden in plant / sexual reproduction forms multicellular zygotes
- Sporophytes, what we call plant / asexual reproduction to form spores that germinate into gametophytes
- Gametophyte (n) → gamete (n) → fertilisation → zygote (2n) → mitosis → sporophyte (2n) → meiosis → spore (n) → mitosis → gametophyte (n)
Animalia (humans, animals);
- Cell structure: eukaryotic, multicellular, no cell wall
- Develop form a blastocyst / embryo
- Have nervous and hormonal control systems
- No cell wall!
- Nutrition: heterotrophic, involving a digestive system
- Are motile and grow throughout tissues (no mersitems)
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