Breaking down nature style….
Mnemonic
D
E
C
A
Y
Think back…
Decomposers!
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Materials are broken down (digested) by micro-organisms !!
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We call these micro-organisms DETRITIVORES.
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Detritivores are scavengers which feed on dead plants and
animals or their waste.
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They are essential for recycling of nutrients: without them
dead plant material would not be returned to the soil for new
growth.
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The earth might be covered by deep layers old vegetation and
lots of animal carcasses only slowly breaking down by
physical and chemical processes.
DETRITIVORES such as:
earthworms
maggots
wood lice
How do they help? They breaks up the organic matter, increasing
their surface area
This makes it easier for SAPROPHYTES such as
bacteria and fungi to digest the organic matter
Humans –
Sewage treatment
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On the bottom of the tank is a bed of
porous clinker, about 2 metres deep
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This is covered with a dense slimy film
of bacteria and fungi, together with
small invertebrates such as worms and
insect larvae
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Sewage is trickled over the filter bed
from the rotating arms and the organic
matter present in it is broken down
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Eventually clean water is released into
the river system..
Key Factors:
An experiment to see which conditions are best for decay
1
Leaf discs
2
3
No air and sealed
Sealed
Heated in
oven to
150oC
5
4
Moist soil
Dry soil
kept in warm
room
In which beaker do you think the leaf discs decomposed fastest?
Moist soil
kept in fridge
Beaker No.4 – decomposers like it warm and wet, with plenty of oxygen
Moist soil
ACTIVITY –
Temperature and Bacteria
Unlucky?
Activity Food preservation methods
Anagrams!
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