4.7.2.3. Decomposition (biology only)

Question 1

What factors affect the rate of decay of biological material?

Answer 1

• temperature
• water
• availability of oxygen

Question 2

How does temperature affect the rate of decay of biological material?

Answer 2

• chemical reactions generally occur at a faster rate in warmer conditions
• but if the temperature is too high the enzymes can denature and stop decomposition

Question 3

How does water affect the rate of decay of biological material?

Answer 3

• microorganisms grow faster in conditions with water as it is needed for respiration
• water also makes food easier to digest

Question 4

How does availability of oxygen affect the rate of decay of biological material?

Answer 4

• most decomposers respire aerobically, producing heat
• the increased temperature increases the rate of decay so compost is made quicker

Question 5

What do gardeners and farmers try to do and why?

Answer 5

• try to provide optimum conditions for rapid decay of waste biological material
  
  • if more oxygen available microorganisms respire aerobically, producing heat
  • the increased temperature increases the rate of decay so compost is made quicker
• the decay of biological material produces compost which is used as a natural fertilised for growing garden plants or crops

Question 6

What does anaerobic decay produce?

Answer 6

• microorganisms decompose waste anaerobically to produce methane gas
• can be burnt as a fuel

Question 7

What are biogas generators used to do?

Answer 7

• biogas generators can be used to produce methane as a fuel
• requiring a constant temperature (30 degrees C) so the microorganisms keep respiring
• cannot be stored as a liquid so needs to be used immediately