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Chapter 4

Chapter 4. The Energy of Life. Section 2 Objectives – page 46. Part 1. How Matter and Energy Enter Living Systems. Section 2.2 Summary – pages 46 - 57. The ultimate source for most of the energy for life is the sun.

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Chapter 4

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  1. Chapter 4 The Energy of Life

  2. Section 2 Objectives – page 46 Part 1 How Matter and Energy Enter Living Systems

  3. Section 2.2 Summary – pages 46 - 57 • The ultimate source for most of the energy for life is the sun. • Photosynthesis: The process in which an organism uses the sun’s energy to manufacture food.

  4. Section 2.2 Summary – pages 46 - 57 Photosynthesis

  5. Section 2.2 Summary – pages 46 - 57 Chemosynthesis • Chemosynthesis: the process of using chemicals to create food • Similar to photosynthesis, because it produces carbohydrates, but uses chemical energy instead of light energy.

  6. Section 2.2 Summary – pages 46 - 57 Cellular Respiration • Respiration: The process of releasing energy from carbohydrates to perform the functions of life. • Used by all living things

  7. Section 2.2 Summary – pages 46 - 57 Photosynthesis and Respiration

  8. Section 2.2 Summary – pages 46 - 57 The producers: Autotrophs • Autotroph: An organism that uses light energy (photosynthesis) or energy stored in chemical compounds (chemosynthesis) to make food The consumers: Heterotrophs • Heterotroph: An organism that cannot make its own food and feeds on other organisms

  9. Section 2.2 Summary – pages 46 - 57 The consumers: Heterotrophs • Heterotrophs display a variety of feeding relationships. • Herbivore: A heterotroph that feeds only on autotrophs

  10. Section 2.2 Summary – pages 46 - 57 The consumers: Heterotrophs • Carnivores: heterotrophs that eat other heterotrophs. • This great white shark is an example.

  11. Section 2.2 Summary – pages 46 - 57 The consumers: Heterotrophs • Scavengers: eat organisms that have already died. • This hardhead catfish is a good example of a scavenger that is native to the Alabama Gulf Coast.

  12. Section 2.2 Summary – pages 46 - 57 The consumers: Heterotrophs • Decomposer: An organism that feeds on and breaks down dead plant or animal matter, thus recycling nutrients in the ecosystem.

  13. Section 2 Objectives – page 46 Part 2 The Ocean’s Primary Productivity

  14. Section 2.2 Summary – pages 46 - 57 Primary Production • Primary production: the creation of energy-rich compounds (carbohydrates) by autotrophs • Carbohydrate: the primary energy storage molecule for living organisms. • Primary production is measured in terms of the amount of carbon that is fixed into organic material per square meter of surface area per year. (gC/m2/yr)

  15. Section 2.2 Summary – pages 46 - 57 Marine Biomass • Biomass is the total mass of living matter at each trophic level. • A pyramid of biomass represents the total weight of living material available at each trophic level. • Standing Crop: the biomass of producers at a given time. Pyramid of Biomass 1 kilogram of human tissue 10 kilograms of beef 100 kilograms of grain

  16. Section 2.2 Summary – pages 46 - 57 Marine Primary Productivity • Compared to terrestrial primary productivity • Overall marine productivity is only slightly less • Marine standing crop is significantly less • Marine ecosystem cycles energy and nutrients much more rapidly • Marine primary producers are phytoplankton

  17. Section 2.2 Summary – pages 46 - 57 Plankton • Plankton: Organisms that exist adrift in the ocean, unable to swim against currents and waves, most, but not all are very small or microscopic • Not a single species • Both autotrophs and heterotrophs • Phytoplankton: autotrophic plankton • Zooplankton: heterotrophic plankton • Feed on phytoplankton and other zooplankton

  18. Section 2.2 Summary – pages 46 - 57 Plankton • Meroplankton: organisms that only live part of their lives as plankton • Ex: fish larvae • Holoplankton: organisms that live their entire lives as plankton • Ex: diatoms

  19. Section 2.2 Summary – pages 46 - 57 Phytoplankton • The most important primary producers in the marine environment. • Account for between 92% and 96% • Marine plants, kelp, and other multicellular photosynthesizing organisms account for 2%-5% • Deep ocean chemosynthesis accounts for the remainder.

  20. Section 2.2 Summary – pages 46 - 57 Phytoplankton: four primary kinds • Diatoms • Most efficient photosynthesizers known • Convert more than half the light energy they absorb into carbs • Cell wall made of silica • Silica: a transparent, glass-like material • Admits light • Can be subject to photoinhibition • Photoinhibition: The condition in which excess light overwhelms an autotroph’s ability to photosynthesize

  21. Section 2.2 Summary – pages 46 - 57 Phytoplankton: four primary kinds • Dinoflagellates • Characterized by 1 or 2 flagella • Flagella: a whip-like tail used for locomotion • Most are autotrophic, but a few are heterotrophic • Reproduce extremely rapidly • Responsible for most plankton blooms • Ie: red tide

  22. Section 2.2 Summary – pages 46 - 57 Phytoplankton: four primary kinds • Coccolithophores • Shell made of calcium carbonate • Calcium carbonate: translucent, milky-white material • Screens out some light • Live in brightly lit, shallow water • All Autotrophic • Reproduce extremely rapidly • Responsible for most plankton blooms • ie: red tide

  23. Section 2.2 Summary – pages 46 - 57 Phytoplankton: four primary kinds • Silicoflagellates • Internal supporting structures made of silica • Both autotrophic and heterotrophic • Have one long flagellum

  24. Section 2.2 Summary – pages 46 - 57 Limits on Marine Productivity • Limiting Factors: physiological or biological necessities that restrict survival • Too much or too little will affect survival • Light • Too little stops photosynthesis • Too much results in photoinhibition

  25. Section 2.2 Summary – pages 46 - 57 Limits on Marine Productivity • Nutrients • Too little limits population growth • Eutrophication: can result in harmful plankton blooms • Eutrophication: over abundance of nutrients in an ecosystem • Plankton Bloom: overpopulation of photosynthysizers that depletes nutrient supply in an area • In extreme cases, can deplete oxygen supply in water

  26. Section 2 Objectives – page 46 Part 3 Energy Flow Through the Biosphere

  27. Section 2.2 Summary – pages 46 - 57 Food chains: Pathways for matter and energy • A food chain is a simple model that scientists use to show how matter and energy move through an ecosystem. • In a food chain, nutrients and energy move from autotrophs to heterotrophs and, eventually, to decomposers.

  28. Section 2.2 Summary – pages 46 - 57 Food chains: Pathways for matter and energy • A food chain is drawn using arrows to indicate the direction in which energy is transferred from one organism to the next. berries → mice → black bear

  29. Section 2.2 Summary – pages 46 - 57 Trophic Relationships • Each organism in a food chain represents a feeding step, or trophic level, in the passage of energy and materials. • Primary Consumer: first trophic level; an organism that feeds on primary producers

  30. Section 2.2 Summary – pages 46 - 57 Trophic Relationships • Secondary Consumer: organism that feeds on a primary consumer. • Tertiary Consumer: an organism that feeds on a seconary consumer • A food chain represents only one possible route for the transfer of matter and energy through an ecosystem.

  31. Section 2.2 Summary – pages 46 - 57 Food webs • Ecologists interested in energy flow in an ecosystem may set up experiments with as many organisms in the community as they can. • The model they create, called a food web, shows all the possible feeding relationships at each trophic level in a community.

  32. Section 2.2 Summary – pages 46 - 57 Food webs

  33. Section 2.2 Summary – pages 46 - 57 Food chains: Pathways for matter and energy • Most food chains consist of two, three, or four transfers. • The amount of energy remaining in the final transfer is only a portion of what was available at the first transfer. • A portion of the energy is given off as heat at each transfer.

  34. Section 2.2 Summary – pages 46 - 57 Energy and trophic levels: Ecological pyramids Pyramid of Energy Heat 0.1% Consumers • The pyramid of energy illustrates that the amount of available energy decreases at each succeeding trophic level. 1% Consumers Heat 10% Consumers Heat 100% Producers Heat Parasites, scavengers, and decomposers feed at each level.

  35. Section 2.2 Summary – pages 46 - 57 Energy and trophic levels: Ecological pyramids • The total energy transfer from one trophic level to the next is only about ten percent because organisms fail to capture and eat all the food energy available at the trophic level below them.

  36. Section 2.2 Summary – pages 46 - 57 Energy and trophic levels: Ecological pyramids • Some of the energy transferred at each successive trophic level enters the environment as heat, but the total amount of energy remains the same.

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