Classification

• Eukaryotes


  Organisms that have a membrane-bound nucleus and organelles inside their cells

  
• Eukaryotic cells


  • Cells of animals, plants and fungi
  • Can be unicellular or multicellular

  
• Prokaryotes


  Bacteria, the simplest of organisms made of single cells with simpler cell structure than eukaryotes
• Prokaryotic cells


  • Do not have an organized nucleus or membrane-bounded organelles
• Plants


  • Multicellular organisms
  • Cells contain chloroplasts and can carry out photosynthesis
  • Cells have cellulose cell walls
  • Store carbohydrates as starch or sucrose
  • Contain a large, central cell vacuole
• Plants


  • Flowering plants, such as a cereal (for example, maize), and a herbaceous legume (for example, peas or beans)
• Animals


  • Multicellular
  • Cells contain a nucleus with a distinct membrane
  • Cells do not have cellulose cell walls
  • Cells do not contain chloroplasts (so they are unable to carry out photosynthesis)
  • Feed on organic substances made by other living things
  • Often store carbohydrates as glycogen
  • Have nervous coordination
  • Able to move from place to place
• Fungi


  • Multicellular, such as mushrooms, toadstools and moulds
  • Can also be single-celled, such as yeast
  • Some are pathogens
  • Cells have a cell wall made of chitin
  • Organised into a mycelium made from thread-like hyphae containing many nuclei
  • Use saprotrophic nutrition, secreting enzymes to digest food outside cells and then absorbing the digested organic products
  • Store carbohydrate as glycogen
• Protoctists


  Microscopic single-celled organisms, some with animal-like features, others with plant-like chloroplasts, some are pathogens
• Bacteria


  • Microscopic single-celled prokaryotic organisms
  • Have a cell wall made of polysaccharides and proteins, a cell membrane, cytoplasm, and a circular chromosome of DNA in the nucleoid
  • Some can carry out photosynthesis, most feed off other living or dead organisms
  • Use flagella to move
• Bacteria


  • Lactobacillus bulgaricus (a rod-shaped bacterium used in yoghurt production)
  • Pneumococcus (a spherical bacterium that causes pneumonia)
• Viruses


  • Non-living particles smaller than bacteria, that cannot perform life processes on their own and can only reproduce inside living cells
  • Have a protein coat and contain either DNA or RNA, but no cellular structure

  
• Viruses


  • Tobacco mosaic virus (causes discolouring of tobacco leaves)
  • Influenza virus (causes flu)
  • HIV virus (causes AIDS)
  • Bacteriophage (infects bacteria)