Energy and Life
What Keeps Us and Other Organisms Alive? Four major components of the earth s life-support system: atmosphere (air) hydrosphere (water) geosphere (rock, soil, sediment) biosphere (living things).
Atmosphere Soil Biosphere Rock Biosphere (living organisms) Mantle Core Atmosphere (air) Geosphere (crust, mantle, core) Hydrosphere (water) Fig. 3-2, p. 41
What Keeps Us and Other Organisms Alive? Life is sustained by the flow of energy from the sun through the biosphere, and the cycling of nutrients within the biosphere.
Solar Energy Reaching the Earth Natural greenhouse effect Energy in = energy out Human-enhanced global warming
Solar radiation UV radiation Most absorbed by ozone Visible light Reflected by atmosphere Lower Stratosphere (ozone layer) Troposphere Radiated by atmosphere as heat radiated by the earth Absorbed by the earth Greenhouse effect Fig. 3-3, p. 41
Living and Nonliving Components Abiotic (without life) Water Air Nutrients Solar energy Rocks
Living and Nonliving Components Biotic (Life) Plants Animals Microbes
Ecology How organisms interact with biotic and abiotic environment Focuses on specific levels of matter: Organisms Populations Communities Ecosystems Biosphere
Levels of Organization Organism: An individual living thing that is made of cells, uses energy, reproduces, responds, grows, and develops
Levels of Organization Population: A group of organisms, all of the same species, which interbreed and live in the same place at the same time.
Levels of Organization Community: All the populations of different species that live in the same place at the same time.
Levels of Organization Ecosystem: Populations of plants and animals that interact with each other in a given area with the abiotic components of that area. (terrestrial or aquatic)
Levels of Organization Biosphere: The portion of Earth that supports life.
What level of organization? Organism
What level of Organization? Community
What level of Organization? Population 17
Trophic Levels Producers autotrophs Photosynthesis Consumers heterotrophs Primary - herbivores Secondary - carnivores Tertiary-level Omnivores
Trophic Levels Decomposers Release nutrients from the dead bodies of plants and animals Detritivores Feed on the waste or dead bodies of organisms
Precipitation Oxygen (O 2 ) Carbon dioxide (CO 2 ) Producer Primary consumer (rabbit) Secondary consumer (fox) Producers Water Decomposers Soluble mineral nutrients Fig. 3-5, p. 43
Energy Flow and Nutrient Recycling Ecosystems sustained through: One-way energy flow from the sun Nutrient recycling
Abiotic chemicals (carbon dioxide, oxygen, nitrogen, minerals) Solar energy Decomposers (bacteria, fungi) Producers (plants) Consumers (herbivores, carnivores) Fig. 3-7, p. 45
Energy in an Ecosystem? As energy flows through ecosystems in food chains and webs, the amount of chemical energy available to organisms at each succeeding feeding level decreases.
Energy Flow in Trophic levels Food chain Ecosystems Sequence of organisms, each of which serves as a source of food for the next Food web Network of interconnected food chains More complex than a food chain
First Trophic Level Second Trophic Level Third Trophic Level Fourth Trophic Level Producers (plants) Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (top carnivores) Solar energy Decomposers and detritus feeders Fig. 3-8, p. 46
Humans Blue whale Sperm whale Crabeater seal Killer whale Elephant seal Adelie penguin Leopard seal Emperor penguin Petrel Squid Fish Carnivorous plankton Krill Herbivorous zooplankton Phytoplankton Fig. 3-9, p. 46
Usable energy available at each trophic level (in kilocalories) Tertiary consumers 10 (human) Secondary consumers (perch) 100 Decomposers Primary consumers (zooplankton) 1,000 Producers (phytoplankton) 10,000 Fig. 3-10, p. 47
Terrestrial Ecosystems Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest (taiga) Savanna Agricultural land Woodland and shrubland Temperate grassland Tundra (arctic and alpine) Desert scrub Extreme desert Aquatic Ecosystems Estuaries Lakes and streams Continental shelf Open ocean 800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600 Average net primary productivity (kcal/m 2 /yr) Fig. 3-11, p. 48