Nutrition

• Photosynthesis


  The process of converting light energy to chemical energy
• Word equation for photosynthesis

  Carbon dioxide + Water -> Glucose + Oxygen
• Balanced chemical symbol equation for photosynthesis

  6CO2 + 6H2O -> C6H12O6 + 6O2
• Factors affecting rate of photosynthesis

  • Carbon dioxide concentration
  • Light intensity
  • Temperature
• Leaf structure


  Adapted for photosynthesis
• Mineral ions required by plants for growth


  • Magnesium ions (for chlorophyll)
  • Nitrate ions (for amino acids)
• Practical investigation of photosynthesis

  1. Showing evolution of oxygen from water plant

  2. Showing production of starch

  3. Showing requirements of light, carbon dioxide and chlorophyll
• Characteristics of living organisms


  • Require nutrition
  • Respire
  • Excrete waste
  • Respond to surroundings
  • Move
  • Control internal conditions
  • Reproduce
  • Grow and develop
• Eukaryotic organisms


  • Multicellular
  • Contain chloroplasts and can photosynthesise
  • Have cellulose cell walls
  • Store carbohydrates as starch or sucrose
• Plants


  • Flowering plants (e.g. maize, peas, beans)
• Animals


  • Multicellular
  • Lack chloroplasts and cannot photosynthesise
  • Lack cell walls
  • Have nervous coordination and can move
  • Store carbohydrates as glycogen
• Fungi


  • Cannot photosynthesise
  • Body organised into mycelium of hyphae
  • Some single-celled
  • Cell walls made of chitin
  • Feed by extracellular secretion of digestive enzymes (saprotrophic nutrition)
  • Store carbohydrates as glycogen
• Fungi


  • Mucor
  • Yeast
• Protoctists


  • Microscopic single-celled organisms
  • Some have animal-like features (e.g. Amoeba)
  • Some have plant-like chloroplasts (e.g. Chlorella)
  • Include pathogenic examples (e.g. Plasmodium causing malaria)
• Prokaryotic organisms (bacteria)


  • Microscopic single-celled
  • Have cell wall, cell membrane, cytoplasm, plasmids
  • Lack nucleus but have circular chromosome of DNA
  • Some can photosynthesise, most feed on other living/dead organisms
• Bacteria


  • Lactobacillus bulgaricus (rod-shaped, used in yoghurt)
  • Pneumococcus (spherical, causes pneumonia)
• Pathogen


  Can include fungi, bacteria, protoctists or viruses
• Viruses


  • Not living organisms
  • Small parasitic particles
  • Reproduce only inside living cells
  • Infect all types of living organisms
  • Have protein coat and contain DNA or RNA
• Viruses


  • Tobacco mosaic virus (causes discolouring in tobacco)
  • Influenza virus