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Chapter 3:
The Biosphere
Warm Up
• 1. On average, what percentage of the energy in an
ecosystem is transferred from one trophic level to
the next?
• 2. Where does the rest of the energy go?
• 3. How does energy flow through an ecosystem?
3.4 Cycles of Matter
• Matter is recycled within and between ecosystems.
• Biogeochemical cycles
• Matter is transformed – never created or destroyed destroyed!
Biogeochemical Cycles
• Matter is passed from one
organism to another and to one
part of the biosphere to another.
• Water, Carbon, Nitrogen, and
The Water Cycle
Nutrient Cycles
• Nutrients pass through organisms and the
environment through biogeochemical cycles!
• 1. Carbon cycle
• 2. Nitrogen Cycle
• 3. Phosphorus cycle
The Carbon Cycle
• Carbon = large component of all organic compounds!
• Forms carbon dioxide (important in atmosphere and
• Oil, natural gas, coal (fossil fuels)
The Carbon Cycle
The Nitrogen Cycle
• Nitrogen gas makes up 78% of earth’s atmosphere
• Organisms need nitrogen to make amino acids and
nucleic acids
• Nitrogen fixation: Bacteria convert nitrogen gas into
• Denitrification: Bacteria obtain energy by converting
nitrates into nitrogen gas (released to atmosphere)
Phosphorus Cycle
• Phosphorus forms a part of DNA and RNA
• Not abundant in atmosphere
• Mostly on land in the form of rock and soil, or as
dissolved phosphate in oceans
• Phosphate released as rocks and sediments wear down
The Phosphorus Cycle
Nutrient Limitation
• Nutrients whose supply limits productivity is called the
limiting nutrient
All nutrient
cycles work
together! If any
nutrient is in
short supply, the
wheel “sticks”
• Growth of crop plants limited by nutrients—so farmers use
• Nitrogen is the limiting nutrient in the ocean, phosphorus is
the limiting nutrient in lakes and freshwater streams