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Cycling of Matter
Earth’s Spheres
Water cycle
Photosynthesis & Cellular Respiration
Carbon cycling
Nitrogen cycling
Phosphorus cycling
Earth’s 4 spheres
Atmosphere (atmos = vapour) Layer of air about Earth’s surface
Hydrosphere (hydro = water) all water found on Earth (including ground water)
Lithosphere (litho = stone)Hard part of Earth’s surface
BiosphereLiving surface of Earthregions where living organisms
exist
Earth’s Spheres
Atmosphere
Lithosphere
Biosphere
Hydrosphere
How does matter cycle through these 4 spheres?
Water, carbon, nitrogen, phosphorus
Water Cycle Atmosphere
Hydrosphere
Lithosphere
Biosphere
Water cycle summarized
• Precipitation• Surface runoff,
infiltration, percolation• Evaporation &
transpiration• Condensation
First Experiment
• Candle in Jar A burned for 3 minutes
• Candle in jar with mint plant burned for 5 minutes
Why?
Joseph Priestley (1733–1804) began a series of experiments that would reveal the essential role of air in the growth of green plants.
• Placed mouse in jar without plant and it died
• Placed mouse in jar with mint plant and lived for a longer period of time. (eventually died)
Second Experiment
Why?
Plants and animals help each other.
Now scientists know that plants use carbon dioxide and water to make sugar and oxygen is released as sugars are made.
Conclusion
The mouse used oxygen from the plant to break down sugars. When your body breaks down sugar carbon dioxide and water are released.
This process is called cellular respiration
Cellular Respiration Process of converting food energy into chemical
energy that can be used by every cell in the organism
(it’s like exchanging Canadian dollars for US currency which is accepted worldwide)
Occurs in the mitochondria
Cellular Respiration
Summarized in this equation:
Breakdown of food into chemical energy
food is often shown as glucose (C6H12O6), a type of
sugar
chemical energy isn’t shown but is known as ATP
requires oxygen
But… where does the food come from?
C6H12O6 + 6O2 → 6CO2 + 6H2O
Ingestion
If you’re an animal, you get food from another organism
Herbivore: ingest plants (e.g. vegetarians)
Carnivore: ingest animals
Omnivore: ingest both plants and animals
If you’re lucky enough to be a plant…
then you can MAKE your own food!!!
through a process called…
– Process of converting light energy into stored food energy
– Occurs in chloroplasts of autotrophs
6H2O + 6CO2 ----------> C6H12O6+ 6O2
Photosynthesis
• There is a balance between oxygen and carbon dioxide within the biosphere.
• Plants provide oxygen and sugars
• Animals and plants provide CO2 and water.
• Processes of photosynthesis and cellular respiration are complementary not opposite.
Summary
Thought question…
Do plants perform cellular respiration?
• To answer this question you need to remember what the purpose of cellular respiration is…
• Then think about whether plants have to fulfill that purpose…
?
Carbon Cycle
All living things contain carbon.
Humans receive carbon from the food they eat. Food energy comes from three types of macromolecules: Carbohydrates(spinach, oranges, sugar, bread), Lipids (oil, butter) and Proteins (meat, eggs)
Carbon is recycled through cellular respiration and photosynthesis and this relationship is called the carbon cycle
Fast Track Carbon Cycle
Atmospheric CO2
↓
Photosynthesis in Autotrophs
↓
Digestion in Organisms
↓
Cellular respiration in organisms
The fast-track flow of carbon occurs
between inorganic CO2
in the atmosphere and organic macromolecules found in living organisms.
Thought question…
• Which of the Earth’s spheres does the fast track cycling of carbon take place in?
Introducing the Slow Track Carbon CycleIntroducing the Slow Track Carbon Cycle
• The fast track cycle is a simple exchange of CO2 and glucose.
• The whole carbon cycle is more complex.• Most of the carbon that forms living
organisms is not returned to the atmosphere or water by the fast track cycle.
• Most carbon is returned as CO2 from body waste and the decay of dead organisms through the slow track cycle.
• Why is it called the slow track?… because something delays the cycle, slowing it down.
OrganicOrganic- Contain atoms of C, H
and sometimes O and N.
Examples: protein, sugar and fats.
Glucose
InorganicInorganic- Does not contain a
combination of
C and H.
Examples: CO2 and H2O
Matter in Ecosystems
Are the following molecules organic or Are the following molecules organic or inorganic? inorganic?
Delays in The Cycle – Inorganic CarbonDelays in The Cycle – Inorganic Carbon
• Inorganic carbon can be found in 3 main reservoirs:
Atmosphere Ocean Earth’s crust
Delays in The Cycle – Inorganic CarbonDelays in The Cycle – Inorganic Carbon
• Some carbon in CO2 reacts with sea water (H2O) and form CO32-
(carbonate ion) or HCO3- (bicarbonate ion) CO2 + H2O CO3
2- + HCO3-
• These ions react with calcium (Ca) and form CaCO3 (calcium carbonate)
Ca + CO32- CaCO3
Ca + HCO3- CaCO3 • Calcium carbonate is also found in shells of shellfish• When shellfish die, their shells (and thus calcium carbonate)
end up as layers of sediments at the bottom of the ocean that get crushed and heated and eventually become rock.
Delays in The Cycle – Organic CarbonDelays in The Cycle – Organic Carbon
• Organic carbon is also held in the body of living things.
• When they die and decompose, the carbon eventually returns to the cycle in inorganic form.
• In some ecosystems like bogs, there is very little oxygen, so decaying of the organisms’ dead bodies is very slow.
• The dead animals and plants remain for many years at the bottom of the bogs.
• Over time, more and more sediment piles on top, trapping the decaying organic matter between layers of rocks.
• The result is the formation of the fossil fuels and coal which are all forms of carbon.
Delays in The Cycle – Organic CarbonDelays in The Cycle – Organic Carbon
Delays in The Cycle – Organic CarbonDelays in The Cycle – Organic Carbon
• Similar condition can happen at the bottom of the oceans when decaying aquatic animals and plants are trapped under sediments in a low oxygen environment.
Delay in The Cycle – Slow Track CycleDelay in The Cycle – Slow Track Cycle
• The carbon in the slow track cycle is unavailable until it is released by natural processes such as: – Uplifting – Weathering– Erosion
• Carbon is also released through man-made processes like burning of fossil fuels
Uplifting
• Material that has been “pushed” up from underneath the ground. – Earthquakes– Volcanoes– Events are due to the
movement of the Earth’s plates (called plate tectonics)
Weathering• weathering is the chemical
or physical breakdown of rock material
• example of chemical weathering: acid rain
• example of physical weathering: frost wedging
Erosion
• the removal or transportation of material by agents as running water, ice, wind, etc.
• Eg. Bryce Canyon in Alaska
• Burning of fossil fuels has sped up the slow track carbon cycle
• It takes millions of years to form fossil fuels, yet we’re using it up in only hundreds of years
Global Warming
• Global warming is the rise in temperature that the Earth experiences
• This can be due to the greenhouse effect where certain gases in the atmosphere trap energy from the sun.
• Without these gases, heat would escape back into space and Earth’s average temperature would be colder.
• Because of how they warm our world, these gases are referred to as greenhouse gases. Some examples include: water vapor, carbon dioxide
• Other greenhouse gases on page 8-9 in booklet
• http://www.epa.gov/globalwarming/kids/greenhouse.html
Human Impacts on the slow-track cycleHuman Impacts on the slow-track cycle
Slow Track Carbon Cycle
Carbonates in rock
Fossil Fuels
↓
Uplifting, weathering, erosion
Burning of fossil fuels
↓Atmospheric CO2
The slow-track flow of carbon stores carbon under water and in the ground in the form of inorganic carbonates and organic fossil fuels. The carbon is released naturally over time. Human impact has unfortunately sped up that process.
Nitrogen Cycle
4 steps
Nitrogen makes up 79% of the atmosphere and it exists in an unreative form as N2 gas.
Plants and animals require nitrogen to live. Nitrogen is found in molecules such as proteins and DNA.
Organisms can only use nitrogen in the form of
nitrate (NO3- ).
The nitrogen cycle converts N2 to NO3- which is
incorporated into living things.
Nitrogen
Nitrogen cycle
The nitrogen cycle has four main phases:
1- Nitrogen-fixation/nitrification (converting N2 NO3-)
a) Lightningb) Nitrogen-fixing bacteria
2- Absorption /uptake (NO3- organic compounds)
3- Decomposition (N in organic compounds NO3- )
4- Denitrification (NO3- N2)
Nitrogen Cycle - Overview
1. Nitrogen-fixation / nitrification (2 methods)
2. Absorption / Uptake
4. Denitrification
3. Decomposition
N2 NO3- Organic
compounds (proteins, DNA)
1. Nitrogen fixation
Lightning: Energy from lightning allows N2 and O2 in the air to react with each other to form
NO3-.
Nitrogen-fixing bacteria Bacteria live in the roots of certain plants known as legumes. Legumes are plants that bear seeds in pods.
Examples of legumes: clover, alfalfa, pea, soybeans. -The bacteria are found in bulges called nodules on the roots of the plant.
1. Nitrogen fixation
Bacteria convert N2 to NO3-.
Some of these ions are released into the soil so that the plant can absorb them.
There is a symbiotic relationship between the plant and the bacteria because plants provide bacteria with sugar and bacteria provide plants with nitrate.
1. Nitrogen fixation
Application
Applications of nitrogen-fixing bacteria: crop rotation
Advantages of crop rotation
Disadvantages of crop rotation
Replenish/increase N in soil so future crops will thrive.
Legume crops sell at a lower market price so there is a short-term loss of income.
Absorption /uptake (NO3- organic compounds) Nitrate is dissolved in water in the soil. Plants absorb the nitrate and incorporate it into
organic compounds in their body. Herbivores and omnivores eat plants to obtain
nitrogen.
2. Absorption / uptake
Decomposition (N in organic compounds NO3- )
Waste and dead matter are broken down by a different type of N-fixing bacteria that exists in the
soil. This type of bacteria needs Oxygen/O2 to survive
and are said to be aerobic.
Nitrogen in organic compounds is converted back to nitrates, forming intermediate molecules in the process:
3. Decomposition
Organic compounds NH3 (ammonia) NO2 (nitrite) NO3
(nitrate)
4. Denitrification
Denitrification (NO3- N2) Denitrification is performed by denitrifying bacteria that
are anaerobic, which means that they survive in
environments that lack oxygen.
Denitrification returns NO3- ions back to the atmosphere
in the form of nitrogen gas.
The conversion of nitrate to nitrogen may result in the
production of an intermediate molecule known as nitrite
(NO2).
Soil that contains a lot of nitrate will have a lower pH.
Nitrogen cycle - Summary
1. Nitrogen fixation 2. Absorption
4. Denitrification
3. Decomposition
N2 NO3- Organic
compounds (proteins, DNA)
http://www.biology.ualberta.ca/facilities/multimedia/uploads/intro-biology/ncycle.swf
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