Decomposition Flashcards
what does decomposition essentially do
- it returns elements that organisms have taken from the world around them
- back into the soil or the air
what is nearly all decomposition done by
- microorganisms
- such as soil bacteria and fungi
what are the three factors that the rate of decay depends on
- temperature
- water content
- oxygen availability
how does temperature affect the rate of decay
- a warm temperature increases the rate of enzyme-controlled reactions in microbes
- so decay happens faster
- enzymes denature if the temperature gets too high
how does water content affect the rate of decay
- decay takes place faster in moist environments
- because organisms involved in decay need water to survive and carry out biological processes
how does oxygen availability affect the rate of decay
- the rate of decomposition is faster when there is lots of oxygen available
- many microbes need oxygen for aerobic respiration
- some decomposers dont need oxygen to respire, but these decomposers work more slowly
what do we do to preserve food
- we use methods that slow decomposition
- by making oxygen availability, water content and temperature less suitable for microorganisms survival and reproduction
what are the three methods that are mainly used for food preservation
- storing foods in a fridge or freezer
- storing food in airtight cans
- drying food
how does storing food in a fridge or freezer preserve it
- it lowers the temperature of the food
- this slows down he decomposers rate of reproduction
- it stops all together in the case of freezing
how does storing food in airtight cans preserve it
- it stops microorganisms from getting in
- once the food is in the cans are sealed and sterilised
- by exposing them tot a high pressure and temperature
- to kill any microorganisms present
how does drying food preserve it
- it removes the water that the microorganisms need to survive and reproduce
- so does adding salt and sugar
- which causes the microorganisms to lose water by osimosis
what is compost
- decomposed organic matter
- that is used as a fertiliser for crops and plants
where is compost produced the quickest (what environment)
- in warm and moist conditions
- where there is plenty of oxygen available
how do compost bins create the ideal conditions for decomposers
- some have mesh sides to increase the oxygen availability
- decomposing materials is kept moist and heat is generated by the decomposers themselves
- some compost bins are insulated to increase the temperature further
how would you calculate the change in the rate of decomposition during two different time periods in an exam
subtract the lower rate from the higher rate
