Decay

• What`s a decomposition?

  the process by which dead organic matter is broken down into simpler organic or inorganic substances, such as carbon dioxide, water, simple sugars, and minerals.
• Which two groups carry out the decompostion?

  detritus feeders (detritivores), and decomposers.
• What are detritus feeders?

  small animals like worms and woodlice that feed on dead organic matter
• What are decomposers?

  microorganisms, such as bacteria and fungi
• What are the three factors that affect the rate of decomposition?

  Water content, oxygen availability and temperature
• What effect would lowering the temperature have on the rate of decay of an apple?

  Decrease the rate of decay
• What process do bacteria need oxygen for?

  Aerobic respiration
• Why could the rate of decomposition fall if soil becomes waterlogged?

  • (Water fills the air gaps within the soil, so there will be) less oxygen 
  • Less aerobic respiration
  • Fewer chemical reactions and thus slower decomposition
• What is a compost?

  a mixture of decayed organic material that is used to fertilise and improve the soi
• What is compost made of?

  Dead plants
• Whats the biogas?

  It is the mixture of gases produced due to the anaerobic decay
• What is the main gas in biogas?

  Methane
• Once the gas has been removed from a biogas generator, a sludgy material is left over. 

  What is this sludgy material used for and why?

  • used as a fertiliser
  • it has high levels of useful minerals
• What are the biogas generators?

  large containers in which animal or plant waste is left to decay anaerobically