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Energy and chemicals flow within ecosystems. 12 Energy flows from producers to consumers. First Stop: Primary Producers. Primary Producers. Second Stop: Primary Consumers – the Herbivores. Herbivores. Third Stop: Secondary Consumers – the Carnivores. Carnivores.
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Energy and chemicals flow within ecosystems 12 Energy flows from producers to consumers.
Energy Flows through a Food Web Losses at every “step” in a food chain Inefficiency of energy transfers
Summary 12.1 Energy from the sun passes through an ecosystem in several steps. First, it is converted to chemical energy in photosynthesis. Herbivores then consume the primary producers, the herbivores are consumed by carnivores, and the carnivores, may be consumed by top carnivores.
Summary 12.1 Detritivores and decomposers extract energy from organic waste and the remains of organisms that have died. At each step in a food chain, some usable energy is lost as heat.
Energy and chemicals flow within ecosystems 12.2 Energy pyramids reveal the inefficiency of food chains.
Biomass • only about 10% of the plants in an ecosystem is converted into biomass • Food Energy Pyramid • trophic levels:
Summary 12.2 Energy from the sun passes through an ecosystem in several steps known as trophic levels. Biomass of primary producers in an ecosystem is far greater than the biomass of herbivores. Biomass transferred at each step along the food chain is 10% of the biomass of the organisms being consumed, due to energy lost in cellular respiration. Food chains rarely exceed four levels.
Energy and chemicals flow within ecosystems 12.3 Essential chemicals cycle through ecosystems.
The Most Important Chemical Cycles Carbon Nitrogen Phosphorus Sulfur
Global CO2 levels exhibit a sharp rise and fall within each year
Summary 12.3 Chemicals essential to life, cycle through ecosystems. Captured from the atmosphere, soil, or water by growing organisms; passed from one trophic level to the next as organisms eat other organisms; Returned to the environment through respiration, decomposition, and erosion. human activities increase the amounts of the chemicals utilized or released to the environment.
Species interactions influence the structure of communities. 12.4 Interacting species evolve together.
Coevolution • predator/prey • parasite/host • competitive species • mutualistic species
Penicillin was first isolated from a fungus growing on a plate of bacteria.
Summary 12.4 In producing organisms better adapted to their environment, natural selection does not distinguish between living and non-living (biotic and abiotic) things as selective forces.
