Download Recycling – Revision Pack (B2) The Carbon Cycle: Carbon is one of

Recycling – Revision Pack (B2)
The Carbon Cycle:
Carbon is one of many elements which are found in living organisms.
Carbon needs to be recycled so that it can become available to other living
organisms.
In photosynthesis carbon dioxide is removed from the air.
Feeding passes carbon compounds along a food chain or web.
Carbon dioxide can be released into the air by:
-
Plants and animals respiring
Soil bacteria and fungi acting as decomposers
The burning of fossil fuels
Carbon dioxide is absorbed from the air by oceans. Marine organisms make shells
made out of carbonates, which become limestone rocks. The carbon in the
limestone can return to the air as carbon dioxide during volcanic eruptions or
weathering.
The Nitrogen Cycle:
Eaten
Proteins in plants
Plants take in
nitrogen as
nitrates from the
soil to make
protein for
growth.
Feeding passes
nitrogen
compounds
along a food
chain or web.
Plants and
animals die
and decay
Proteins in Animals
The nitrogen compounds in
dead plants and animals are
broken down by decomposers
and return to the soil.
A number of microorganisms
are responsible for the
recycling of nitrogen.
Decomposers
Nitrates in the soil
For example, decomposers are
soil bacteria and fungi and
convert proteins and urea into
ammonia.
Recycling – Revision Pack (B2)
Bacteria
Nitrifying bacteria
Job in recycling nitrogen
Converts ammonia into nitrates
Denitrifying bacteria
Converts nitrates into nitrogen gas
Nitrogen-Fixing bacteria
Live in the root nodules or soil, and fix
nitrogen gas in the air into nitrates in the
soil – also occurs by the action of
lightning
Keeping Decomposers Working:
For decomposers to be able to break down dead material in soil, they need oxygen
and a suitable pH.
Decay will therefore be slower in waterlogged soils because there is less oxygen.
Decay will also be slower in more acidic conditions.
Recycling – Revision Pack (B2)
Past Papers:
PPQ(1):
PPQ(2):
Recycling – Revision Pack (B2)
PPQ(3):
PPQ(4):
Recycling – Revision Pack (B2)
Mark Schemes:
PPQ(1):
PPQ(2):
PPQ(3):
PPQ(4):