Use of Biological Resources

• Glasshouses and polytunnels increase yield of crops by:

  1. Keeping crops free from pests and disease
  2. Control the water supply for plants
  3. Artificial light after Sun goes down to allow the plants more time to photosynthesise
  4. Trap Sun's heat/ use a heater in the Winter to keep plants at optimum temperature for photosynthesis
  5. Use vents to open and cool to keep plants at optimum temperature for photosynthesis
  6. Increase Carbon Dioxide levels using paraffin heaters as by heating paraffin carbon dioxide is a by-product for photosynthesis
• The limiting factors of photosynthesis are light, carbon dioxide concentration and temperature. Glasshouses and polytunnels are used to control these factors.
• Paraffin heaters carry out equation $Fuel+$$Oxygen -> Carbon Dioxide +$$Water$
• Fertilisers contain nitrates, phosphorus and potassium which are the minerals that plants need to to make important compounds such as proteins and carbohydrates. Hence, fertilisers increase crop yield.
• Pests: Microorganisms, insects and mammals that feed on crops
• Pesticide: A chemical used to kill pests. They are often poisonous to human and wildlife
• Advantages of pesticides:

  1. Easily accessible and relatively cheap
  2. Have an immediate effect
  3. Kills the entire population of pests
• Disadvantages of pesticides:

  1. Organisms can become resistant to them
  2. They can kill other organisms as well as target pest
  3. They can accumulate in food chains
  4. Must be reapplied
• Advantages of Biological Control:

  1. Natural method - no pollution
  2. Organisms won't become resistant
  3. Can target specific species
  4. Long-lasting - does not require reapplication
• Disadvantages of Biological Control:

  1. May eat other organisms and not pest
  2. Is it not an immediate effect
  3. Cannot kill entire population
  4. May move out of target area
  5. May become pest itself
• Yeast is a microbe that can be used in food production
• Yeast is used for making bread and alcohol
• When yeast respire in dough, they release carbon dioxide which is trapped by the dough and causes it to rise
• Yeast produce alcohol by being placed in an anoxic environment so they can carry out anaerobic respiration to produce ethanol.
• Fermentation of yeast: A process that produces ethanol and carbon dioxide from glucose using yeast.
• The enzymes in yeast break down the carbohydrates in the flour of the dough into sugars that can be used for respiration.
• When the bread dough is baked in the oven, the yeast continues to ferment until the temperature is high enough to kill the yeast and any alcohol that has been produced from anaerobic respiration is boiled off. The bread stops rising when the yeast is dead.
• To create anaerobic conditions in an experiment, put layer of oil on top of mixture as this will prevent oxygen from getting in.
• To investigate the role of anaerobic respiration in yeast in different conditions, put the yeast mixture in test tubes with a layer of oil for anaerobic conditions. If changing temperature use different temperature water baths and count the bubbles of carbon dioxide produced.
• Fermentation in general: microorganisms breaking sugars down to release energy, usually by anaerobic respiration
• The bacteria Lactobacillus is used to make yoghurt
• Steps of yoghurt production:

  1. Sterilise equipment with heat to kill microbes
  2. Pasteurise milk to kill microbes in milk
  3. Cool milk so lactobacillus is not killed
  4. Add lactobacillus and incubate to allow bacteria to grow and reproduce
  5. Lactobacillus breaks down lactose in milk into lactic acid, making the milk thick, acidic and sour
  6. Cool to slow down to growth of lactobacillus
  7. Add flavourings
• Aseptic: sterile from microbes
• Fermenters are used to grow microorganisms so they can be used for medicines like penicillin or insulin.
• Conditions for a fermenter:

  1. Nutrients are need for microorganism growth and added as part of the culture medium liquid

  
• Conditions for fermenter:

  2. Steam is added to sterilise and kill other microbes as having aseptic conditions increases product yield as the microorganism isn't competing and removes contamination.

  
• Conditions for fermenter:

  3. Exhaust gases are filtered as they leave the fermenter to prevent biohazard to external environment

  
• Conditions of fermenter:

  4. Water-cooled jacket keeps optimum temperature so the enzymes do not denature. Heat is produced by respiration so needs cooling

  
• Conditions of fermenter:

  5. Paddles mix the microorganism and nutrients and distributes heat and air. Prevents the build up of waste products.

  
• Conditions of fermenter:

  6. Stainless steel provides smooth surface which allow the hot steam to clean and remove microbes and avoids corrosion

  
• Conditions for fermenter:

  7. pH monitor to keep optimum pH for enzymes and keeps product yield high

  
• Conditions for fermenter:

  8. Air pump to give oxygen to microorganisms for respiration which increases product yield

  
• Intraspecific predation: predation by the same species
• Interspecific predation: predation by different species on same prey
• Aquaculture: Fish farming
• Fish are a source of protein when eaten
• Methods to fish farm effectively:

  1. Maintain good water quality by filtering waste, monitoring pH, temperature and oxygen level
  2. Having a cage to protect from interspecific predation and to stop them using too much energy
  3. Separating fish depending size to prevent intraspecific predation
  4. Biological pest control and removing disease-ridden fish to prevent passing on disease to fish
  5. Feed little and often with protein to limit energy for movement and quicken growth of fish
  6. Selective breeding to only reproduce healthy fish
• Selective breeding: The process of breeding organisms to produce offspring with desirable characteristics.
• Selective breeding can increase plants crop yield as the combination of desirable features can allow the plant to withstand changes in environment.
• Selective breeding can increase desirable traits in animals for maximum yield of farm meat, good health, fertility etc.