topic 5: biological resources

• Glasshouses and polyethene tunnels

  • Protect crops from harsh weather conditions
  • Increase carbon dioxide levels and rate of photosynthesis
  • Trap heat from the Sun to reach optimum enzyme temperature
  • Protect plants from pests and diseases
• Factors affecting crop yield

  • Carbon dioxide
  • Temperature
  • Fertiliser
  • Pest control
• Increasing carbon dioxide levels

  Burn paraffin lamps
• Increased carbon dioxide levels

  Carbon dioxide is not the limiting factor in the rate of photosynthesis
• Increased temperature in glasshouse


  Enzymes in photosynthesis work at optimum temperature, increasing rate of photosynthesis
• Fertilisers


  • Contain nutrients that allow plants to grow faster
  • Water-soluble minerals absorbed by active transport
  • Nitrates required for amino acids and protein growth
  • Phosphates required for respiration and root growth
  • Potassium needed for growth of flowers and fruit, allowing enzyme reactions
• Pest control


  Using pesticides or biological control to prevent insects eating plants
• Pesticides


  • Fungicides
  • Herbicides
  • Insecticides
• Advantages of pesticides


  • Quick and efficient
  • Can kill entire populations
• Disadvantages of pesticides


  • Organisms can develop resistance
  • Non-specific so kills other organisms
  • Bioaccumulation can make it toxic to others in the food chain
  • Have to continuously apply
• Anaerobic respiration in yeast

  Glucose -> Ethanol + Carbon dioxide

  The carbon dioxide bubbles cause the bread to rise
• Investigating anaerobic respiration in yeast

  1. Dissolve sugar in boiled water

  2. Mix yeast with sugar solution in boiling tube

  3. Add layer of oil to prevent oxygen entry

  4. Connect boiling tube to test tube of lime water

  5. Count bubbles over time
• Lactobacillus


  Useful bacteria in making yoghurt

  Breaks down lactose in milk to form lactic acid, lowering pH and denaturing proteins to give yoghurt texture
• Production of yoghurt


  1. Sterilise equipment

  2. Heat milk to 72°C for 15 seconds to pasteurise

  3. Cool milk and add lactobacillus

  4. Incubate at 40°C to allow bacteria to break down lactose

  5. Thickened yoghurt produced, flavourings added before packaging
• Industrial fermenter


  • Requires aseptic conditions
  • Needs nutrients for microorganism respiration
  • Optimum temperature and pH for enzymes
  • Requires agitation to distribute nutrients, oxygen, temperature, pH and microorganisms evenly
• Selective breeding


  Humans choose which organisms to breed to produce offspring with desired characteristics

  Can lead to inbreeding and reduced gene pool, increasing risk of genetic defects and extinction
• Genetic engineering


  Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic
• Production of human insulin

  1. Cut insulin gene from healthy individual using restriction enzymes

  2. Cut virus or bacterial plasmid using same restriction enzyme

  3. Join sticky ends of gene and virus/plasmid using ligase enzymes

  4. Place combined loop in vector like bacterial cell to multiply
• Genetically modified crops


  • Engineered to be resistant to insects and herbicides, increasing yields
• Transgenic


  Transfer of genetic material from one species to a different species