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APES ch3


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APES ch3

  1. 1. Chapter 3Ecosystems and Energy
  2. 2. o Ecology o Potential vs. Kinetic energyo Species o 1st law of thermodynamicso Population o 2nd law of thermodynamicso Community o Photosynthesiso Ecosystem o Cellular Respirationo Atomosphere o Chemosynthesiso Lithosphere o How energy flows through ano Hydrosphere ecosystemo Heterotrophs o Producerso Omnivores o Consumers (primary, secondary,o Detritus tertiary)o Trophic levels o Decomposers/Saprotrophso Gross primary productivityo Ecological pyramid (numbers, (GPP) biomass, energy)o Net primary productivity (NPP)
  3. 3. Overview of Chapter 3o Ecologyo Energy • First Law of Thermodynamics • Second Law of Thermodynamicso Photosynthesis and Cellular Respirationo Flow of Energy Through Ecosystems • Producers, Consumers & Decomposers • Ecological Pyramid • Ecosystem Productivity
  4. 4. o Ecology Ecology • “eco” house & “logy” study of • The study of interactions among and between organisms in their abiotic environment • Broadest field in biologyo Biotic- • living environment • Includes all organismso Abiotic- • non living or physical environment • Includes living space, sunlight, soil, precipitation, etc.
  5. 5. Ecologyo Biology is very organizedo Ecologists are interested in the levels of life above that of organism
  6. 6. Ecology Definitionso Species • A group of similar organisms whose members freely interbreedo Population • A group of organisms of the same species that occupy that live in the same area at the same timeo Community • Al the populations of different species that live and interact in the same area at the same timeo Ecosystem • A community and its physical (abiotic) environmento Landscape • Several interacting ecosystems
  7. 7. Ecologyo Biosphere contains earth’s communities, ecosystems and landscapes, and includes: • Atmosphere- gaseous envelope surrounding earth • Hydrosphere- earth’s supply of water • Lithosphere- soil and rock of the earth’s crust
  8. 8. Energyo The ability or capacity to do work • Chemical, radiant, thermal, mechanical, nuclear, electricalo Energy exists as: • Stored energy (potential energy) • Kinetic energy (energy of motion)
  9. 9. Thermodynamicso Study of energy and its transformationso System- the object being studied • Closed System- Does not exchange energy with surroundings (rare in nature) • Open System- exchanges energy with surroundings
  10. 10. Laws of Thermodynamicso First Law of Thermodynamics • Energy cannot be created or destroyed; it can change from one form to another • Ex: organisms cannot create energy they need to survive- they must capture it from another source • Focus is on quantityo Second Law of Thermodynamics • When energy is converted form one form to another, some of it is degraded to heat • Heat is highly entropic (disorganized) • Focus is on quality
  11. 11. Photosynthesiso Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of sugar molecules 6 CO2 + 12 H2O + radiant energy C6H12O6 + 6 H2O + 6 O2o Energy captured by plants via photosynthesis is transferred to the organisms that eat the plants
  12. 12. Cellular Respirationo The process where the chemical energy captured in photosynthesis is released within cells of plants and animals C6H12O6 + 6 O2 + 6 H2O 6 CO2 + 12 H2O + energyo This energy is then used for biological work • Creating new cells, reproduction, movement, etc.
  13. 13. Energy Flowo Passage of energy in a one-way direction through an ecosystem • Producers • Primary consumers • Secondary consumers • Decomposers
  14. 14. Food Chains- The Path of Energy Flowo Energy from food passes from one organisms to another • Each “link” is called a trophic level
  15. 15. Food webs represent interlocking food chains that connect all organisms in an ecosystem
  16. 16. Ecological Pyramidso Graphically represent the relative energy value of each trophic level • Important feature is that large amount of energy are lost between trophic levels to heato Three main types • Pyramid of numbers • Pyramid of biomass • Pyramid of energy
  17. 17. Pyramid of Numberso Illustrates the number of organisms at each trophic level • Usually, organisms at the base of the pyramid are more numerous • Fewer organisms occupy each successive levelo Do not indicate the biomass of the organisms at each level or the amount of energy transferred between levels
  18. 18. Pyramid of Biomasso Illustrates the total biomass at each successive trophic level • Biomass: measure of the total amt of living material • Biomass indicates the amount of fixed energy at a given timeo Illustrates a progressive reduction in biomass through trophic levels
  19. 19. Pyramid of Energyo Illustrates how much energy is present at each trophic level and how much is transferred to the next level • Most energy dissipates between trophic levelso Explains why there are so few trophic levels • Energy levels get too low to support life
  20. 20. Ecosystem Productivityo Gross Primary Productivity (GPP) • Total amount of energy that plants capture and assimilate in a given period of timeo Net Primary Productivity (NPP) • Plant growth per unit area per time • Represents the rate at which organic material is actually incorporated into the plant tissue for growtho GPP – cellular respiration = NPP • Only NPP is available as food to organisms
  21. 21. Variation in NPP by Ecosystem
  22. 22. Human Impact on NPPo Humans consume more of earth’s resources that any other animal • Humans represent 0.5% of land-based biomass • Humans use 32% of land-based NPP!o This may contribute to loss of species (extinction)o Humans’ high consumption represents a threat to planet’s ability to support both human and non-human inhabitants