Carbon and nitrogen cycles.ppt

1. Food Production and
the Environment
The Carbon Cycle

3. Carbon dioxide
in the air

4. Carbon dioxide
in the air
Green plants use
carbon dioxide to
make their food

5. Carbon dioxide
in the air
Green plants use
carbon dioxide to
make their food
Green plants are
eaten by animals

6. Carbon dioxide
in the air
Green plants use
carbon dioxide to
make their food
Green plants are
eaten by animals
respiration

7. carbon dioxide
in the air
green plants use
carbon dioxide to
make their food
green plants are
eaten by animals
respiration
dead remains of plants
and animals

8. carbon dioxide
in the air
green plants use
carbon dioxide to
make their food
green plants are
eaten by animals
respiration
dead remains of plants
and animals
decay by fungi
and bacteria

9. Decay
 Fungi and bacteria
are responsible for
the decay of dead
organisms.

10. Decay
 In order to be able
to carry out decay,
fungi and bacteria
need:
1. Oxygen
2. Moisture
3. The correct
temperature

11. The Nitrogen Cycle

13. nitrogen in
the air

14. nitrogen in
the air
fertilizers
fertilizers

15. nitrogen in
the air
fertilizers
fertilizers
waste
substances
e.g. faeces

16. nitrogen in
the air
fertilizers
fertilizers
waste
substances
e.g. faeces
lightning

17. nitrogen in
the air
fertilizers
fertilizers
waste
substances
e.g. faeces
lightning
Nitrogen-fixing
bacteria in the soil

18. nitrogen in
the air
fertilizers
fertilizers
waste
substances
e.g. faeces
lightning
Nitrogen-fixing
bacteria in the soil
Nitrogen-fixing
bacteria in the root
nodules of clover

19. nitrogen in
the air
fertilizers
fertilizers
waste
substances
e.g. faeces
lightning
Nitrogen-fixing
bacteria in the soil
Nitrogen-fixing
bacteria in the root
nodules of clover
dead remains of
plants and
animals

20. nitrogen in
the air
fertilizers
fertilizers
waste
substances
e.g. faeces
lightning
Nitrogen-fixing
bacteria in the soil
Nitrogen-fixing
bacteria in the root
nodules of clover
dead remains of
plants and
animals
nitrates in the
soil

21. fertilizers
fertilizers
waste
substances
e.g. faeces
lightning
Nitrogen-fixing
bacteria in the soil
Nitrogen-fixing
bacteria in the root
nodules of clover
dead remains of
plants and
animals
nitrates in the
soil
denitrifying
bacteria in the soil
break down nitrates

22. The nitrogen cycle
 Living things need
nitrogen to make
protein.
 They can not use the
nitrogen in the air
 The nitrogen in the
air must be changed
to nitrates before
plants can use it.

23. The nitrogen cycle
 Animals get their
nitrogen by eating
plants.

24. The nitrogen cycle
 The roots of some
plants (e.g. clover,
pea & beans) have
swellings called root
nodules on them.
 Nitrogen-fixing
bacteria living in
these nodules
change nitrogen in
the air into nitrates.

25. The nitrogen cycle
 The nitrogen-fixing
bacteria are essential
to maintain the
fertility of the soil.
 Without them food
yields would rapidly
fall.