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  1. Energy

  2. Energy is defined as the ability to do work. • Work is causing a change that would not otherwise occur.

  3. Energy Forms • Kinetic energy = energy of motion • Light energy = electromagnetic radiation energy that travels through space as waves • Potential energy = stored energy • Chemical energy = energy stored in molecules in the bonds between atoms What are some other forms of energy?

  4. Potential energy can be converted into kinetic energy Kinetic energy can be converted into potential energy

  5. First Law of Energy • The First Law of Energy (or conservation of energy principle) states that energy cannot be created or destroyed. Energy can only be converted from one form to another. • The Second Law of Energy states that when energy is converted from one form to another, some energy will be unusable, usually lost as heat.

  6. Calories (kilocalories)= units of energy

  7. ATP • ATP is the source of chemical energy for cellular work.

  8. ATP (adenosine triphosphate)

  9. The ATP Cycle This is really important !

  10. Cellular Respiration • Cellular Respiration is the harvesting of chemical energy from organic fuel molecules (i.e. glucose) and converting that energy into the chemical energy in ATP molecules. • Aerobic cellular respiration • requires oxygen (O2)

  11. Aerobic Cellular Respiration Net Chemical Equation • Can produce 38 ATP • from the energy in ONE Glucose

  12. Aerobic Cellular Respiration • In your body cells; • Where does the Glucose come from? • Where does the Oxygen (O2) come from? • Where does the carbon dioxide (CO2) go?

  13. Aerobic Cellular Respiration • If one glucose molecule contains 686 kcal • and • One ATP molecule contains 7.5 kcal • What is the energy efficiency of aerobic cellular respiration? • What has happened to the remaining energy?

  14. Anaerobic Cellular Respiration • Anaerobic Cellular Respiration harvests energy from food without oxygen. • Fermentation is the most common type of anaerobic cellular respiration. • Fermentation occurs in both • eukaryotic and prokaryotic cells.

  15. Fermentation inHuman Muscle Cells

  16. Fermentation in Yeast

  17. CO2 produced by yeast fermentation makes the air bubbles in baked goods

  18. Ethyl alcohol produced by yeast fermentation is in adult beverages

  19. Fermentation in Microorganisms • Anaerobes are organisms that conduct anaerobic cellular respiration. • Facultative Anaerobes can conduct either aerobic or anaerobic cellular respiration. • Obligate Anaerobes can only conduct anaerobic, and are actually poisoned by oxygen.

  20. Photosynthesis Photosynthesis is the process where green plants (& some bacteria) convert light energy into the chemical energy contained in glucose molecules.

  21. Oxygen seeking bacteria migrate toward algae exposed to certain colors of light.

  22. Photoautotrophs = make own food molecules using light energy

  23. Photoautotrophs can be unicellular eukaryotic organisms

  24. Photoautotrophs can be prokaryotic organisms

  25. Photosynthesis Net Chemical Equation Light Energy

  26. Glucose produced is used for; • Cellular Respiration • Starch (stored glucose) • Cellulose (structural) • Other Organic Compounds

  27. Energy Flow Always ONE WAY Flow • Sunlight Glucose ATP

  28. Solar-Driven Evolution Plants that use CO2 directly from the air are called C3 plants (CO2 binds to a three carbon molecule when it enters the plants cells) Common crops like oats, wheat, soybeans and rice C3 plants close their stomata on hot, dry days to reduce the loss of water, but this also prevents CO2 from entering the leaves. Why is this a problem? Alternate modes of incorporating carbon from CO2 have evolved in some plants, allowing them to save water without shutting down photostnthesis.

  29. C4 plants are named for the four-carbon molecule that CO2 binds with inside the cell. This molecule then shuttles the CO2 to a nearby cell, which can keep on making sugars even if the stomata are closed on a hot, dry day. Corn and sugarcane are examples

  30. CAM plants have adapted to very dry climates by opening their stomata and admitting CO2 only at night. CO2 binds a four-carbon molecule at night and releases the CO2 in the same cell for photosynthesis during the day. Examples are pineapples, cacti, and succulents like aloe and jade.

  31. Energy Flow is always ONE WAY thru Ecosystem

  32. Food Chain= sequence of food transfers from producers thru several levels of consumers • Trophic Levels= eating levels in a food chain • Quaternary Consumer • Tertiary Consumer • Secondary Consumer • Primary Consumer • Producer

  33. Decomposers / Detritivores • Detritus = animal wastes, plant litter (detritus), and dead organisms • Detritivores eat detritus, and by breaking it down into molecules that other organisms can use they recycle these nutrients. Termites

  34. Decomposers, mostly bacteria & fungi, are an important trophic level

  35. Food Web = a network of interconnecting food chains

  36. Biomass • Biomass= the weight, or mass, of organic material in an ecosystem • Biomass can be determined for a trophic level, as well as whole ecosystem • Example; The weight of all the plants equals the biomass of the producers

  37. Primary Productivity= the rate at which plants and other producers build biomass, or organic matter in an ecosystem • The primary productivity of the entire biosphere is about 170 billion tons of organic material per year

  38. Primary Productivity varies with environmental conditions

  39. Remember the Second Law of Energy states that when energy is converted from one form to another, some energy will be unusable, usually lost as heat.On average, only about 10% of the energy eaten at each trophic level is stored as biomass in the next trophic level

  40. Energy Pyramids show the energy in all the organisms at each trophic level

  41. Why would it be more efficient for humans to eat more plants and less animals?

  42. Chemicals or Nutrients CYCLE thru an Ecosystem

  43. Biogeochemical Cycles =any of the chemical circuits occurring in an ecosystem, involving both biotic and abiotic components of the ecosystem