B4g - Decay Flashcards
What 3 things does the rate of decay depend on?
temperature
amount of water
amount of oxygen
How does a warm temperature affect the rate of decay?
it makes things decay faster because it speeds up respiration in microorganisms
How does a moist atmosphere affect the rate of decay?
things decay faster because microorganisms need water
How does an oxygen rich atmosphere affect the rate of decay?
decay is faster as microorganisms can respire aerobically providing more energy
What are the optimum levels for microorganisms?
warm
moist
plenty of oxygen
What happens to these microorganisms when these factors are at optimum levels?
microorganisms grow and reproduce more quickly meaning there will be more of them to decay other living things
What are detritivores?
organisms that feed on dead and decaying material
what is detritus?
dead and decaying material
What are some examples of detritivores?
earthworms
maggots
woodlice
How do detritivores increase the rate of decay?
they break up the decaying material into smaller bits giving a bigger surface area for smaller decomposers to work on and speeds up the decay
What is a saprophyte?
an organism that feeds on decaying material through extracellular digestion
What is extracellular digestion?
secreting digestive enzymes on the material outside of their cells. The enzymes break down the material into smaller bits, which can then be absorbed by the saprophyte.
Give an example of a saprophyte
fungi
What are microorganisms used for?
to break down human waste (sewage)
to break down plant waste (compost)
What are the main food preservation techniques?
canning cooling freezing drying adding salt/sugar adding vinegar
How does canning reduce the rate of decay?
by putting food in an airtight can, decomposers are kept out
How does cooling reduce the rate of decay?
putting food in the fridge slows down decay because it slows the decomposers reproduction rate
How does freezing reduce the rate of decay?
food lasts longer in the freezer than in the fridge because decomposers cant reproduce at all at such low temperatures
How does drying reduce the rate of decay?
dried food lasts longer because decomposers need water to carry out cell reactions
How does adding salt/sugar reduce the rate of decay?
if there’s a high concentration of salt/sugar around the decomposers they’ll lose water by osmosis which damages them and means they can’t work properly
How does adding vinegar reduce the rate of decay?
vinegar is acidic and acid kills the decomposers
