Download 07-Nutrient Cycles, Photo. and Resp. Note

Photosynthesis and
Respiration
Because organisms use the energy from the previous
trophic levels to maintain and reproduce much of
it is lost to higher trophic levels (10% rule).
Energy that decomposers get cannot be passed to
producers in food chains therefore we say that
energy does NOT cycle.
• Produces convert the sun’s energy into
chemical energy by the process of
photosynthesis.
– Plants take carbon dioxide and water from
the environment and produce glucose and
oxygen.
WORD EQUATION:
carbon dioxide + water + light energy
glucose + oxygen
CHEMICAL EQUATION:
6CO2 + 6H2O + light energy
C6H12O6 + 6O2
Cellular Respiration:
• The process by which molecules such as
glucose (sugar) are broken down to release
energy required for life processes is known as
Cellular Respiration.
WORD EQUATION:
Glucose + oxygen
carbon dioxide + water + energy
CHEMICAL EQUATION:
C6H12O6 + 6O2
6CO2 + 6H2O + energy
CARBON CYCLE
• The products of respiration are the
reactants of photosynthesis. The products
of photosynthesis are the reactants of
respiration.
• Plants use carbon dioxide to form sugars.
Animals eat these sugars and release carbon
dioxide through respiration.
CARBON CYCLE
• Organic carbon
– Held in the bodies of living things
– Carbon is returned to the atmosphere when
things die and decompose
– Sometimes decay is slowed down (e.g. in wet
areas) and may be converted into rock or fossil
fuels – it’s stuck there until something happens
to release it (e.g. digging it up and using it for
fuel)
• Inorganic carbon
– Carbon in the atmosphere, oceans and
crust of the earth
– Most inorganic carbon is in the ocean
where it is not available to land
organisms.
• Human Impact on Carbon Cycle
– Release organic carbon faster (e.g.
burning fossil fuels, burning forests)
– Increase amount of carbon in the
atmosphere by clearing vegetation
Questions
• What are humans doing that is causing the increased
release of organic carbon?
• Clear Cutting Forest, Burning Fossil Fuels
• What is the effect of this release?
• Global Warming – increase in earth’s temp because of
an increase in carbon dioxide that traps heat
• Where do the producers get the materials for the
production of sugars?
• Carbon Dioxide in the air and water
• How do primary and secondary consumers obtain the
carbon that is necessary for growth and reproduction?
• From consuming other living organisms
NITROGEN CYCLE
• Movement of nitrogen through the
ecosystem.
• Nitrogen is used for:
– Synthesis of DNA
– Protein
– Helps plants grow
• Nitrogen accounts for 79% of the gas
in the atmosphere, but plants are not
able to use it in this form
• Nitrogen fixation:
– When atmospheric nitrogen (N2) is
converted to nitrates which can be used
by plants.
• Two ways of fixing nitrogen:
– Lightning: the energy in lightning can
break the N2 apart and make it able to
combine with other elements so that
plants can use it.
– Bacteria: symbiotic relationship –
bacteria give plants nitrates, plants give
bacteria sugar
• Denitrification:
– When nitrogen gas is released from the
soil back into the atmosphere
• Nitrogen also gets into the soil
through animal droppings and
decaying matter.
• Nitrogen gets into consumers when
they eat plants.
Questions
• Explain how nitrogen is taken from and returned to the
atmosphere?
• Bacteria take it out and put it back
• Why do farmers use decaying matter to help plants
grow?
• Rich in a nitrogen source that plants can use
• What is the process called whereby nitrogen is
returned to the atmosphere?
• Denitrification
• What happens to the nitrogen contained in all living
organisms?
• Used to make proteins or excreted back into the soil
• What impact have humans had on the nitrogen cycle?
• Put nitrogen into the soil with fertilizers