section 1

• Characteristics shared by living organisms

  • Require nutrition
  • Respire
  • Excrete waste
  • Respond to surroundings
  • Move
  • Control internal conditions
  • Reproduce
  • Grow and develop
• Eukaryotic organisms: Plants, Animals, Fungi, Protoctists

  • Multicellular
  • Plants have chloroplasts and carry out photosynthesis, have cellulose cell walls, store carbohydrates as starch or sucrose
  • Animals lack chloroplasts and cannot photosynthesize, have no cell walls, have nervous coordination and can move, store carbohydrates as glycogen
  • Fungi cannot photosynthesize, have a mycelium structure with hyphae, some are single-celled, have chitin cell walls, use saprotrophic nutrition, store carbohydrates as glycogen
  • Protoctists are microscopic single-celled, some have animal-like features, some have chloroplasts and are more plant-like
• Prokaryotic organisms: Bacteria


  • Microscopic single-celled
  • Have cell wall, cell membrane, cytoplasm, plasmids
  • Lack a nucleus but have a circular chromosome of DNA
  • Some can photosynthesize, most feed off other living or dead organisms
• Pathogen


  Fungi, bacteria, protoctists or viruses that can cause disease
• Viruses


  • Not living organisms, small parasitic particles
  • Reproduce only inside living cells
  • Wide variety of shapes and sizes
  • No cellular structure, have a protein coat and contain DNA or RNA
• Pathogenic examples


  • Plasmodium (causes malaria)
  • Tobacco mosaic virus (causes discolouring of tobacco leaves)
  • Influenza virus (causes flu)
  • HIV virus (causes AIDS)