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Energy can be transformed from one form to another

Energy can be transformed from one form to another. FREE ENERGY (available for work) vs. HEAT (not available for work) . THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH. THE FOOD WEB. WHY ARE PLA NTS GRE EN?.

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Energy can be transformed from one form to another

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  1. Energy can be transformed from one form to another FREE ENERGY (available for work) vs. HEAT (not available for work)

  2. THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH

  3. THE FOOD WEB

  4. WHY ARE PLANTS GREEN? Different wavelengths of visible light are seen by the human eye as different colors. Gammarays Micro-waves Radio waves X-rays UV Infrared Visible light Wavelength (nm)

  5. Electromagnetic Spectrum and Visible Light Gammarays Infrared & Microwaves X-rays UV Radio waves Visible light Wavelength (nm)

  6. WHY ARE PLANTS GREEN? Plant Cells have Green Chloroplasts The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigments (i.e., chlorophylls, carotenoids).

  7. THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED • Chloroplasts absorb light energy and convert it to chemical energy Reflected light Light Absorbed light Transmitted light Chloroplast

  8. Chloroplast Pigments • Chloroplasts contain several pigments • Chlorophyll a • Chlorophyll b • Carotenoids Figure 7.7

  9. Excitation of chlorophyll in a chloroplast • Loss of energy due to heat causes the photons of light to be less energetic. • Less energy translates into longer wavelength. • Energy = (Planck’s constant) x (velocity of light)/(wavelength of light) • Transition toward the red end of the visible spectrum. e e Excited state 2 Heat Light Light (fluorescence) Photon Ground state Chlorophyll molecule (a) Absorption of a photon (b) fluorescence of isolated chlorophyll in solution

  10. THE BASICS OF PHOTOSYNTHESIS • Almost all plants are photosynthetic autotrophs, as are some bacteria and protists • Autotrophs generate their own organic matter through photosynthesis • Sunlight energy is transformed to energy stored in the form of chemical bonds (c) Euglena (d) Cyanobacteria (b) Kelp (a) Mosses, ferns, and flowering plants

  11. Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2

  12. Chloroplast LEAF CROSS SECTION MESOPHYLL CELL • The location and structure of chloroplasts LEAF Mesophyll Intermembrane space CHLOROPLAST Outer membrane Granum Innermembrane Grana Stroma Thylakoidcompartment Stroma Thylakoid

  13. AN OVERVIEW OF PHOTOSYNTHESIS • Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water Carbondioxide Water Glucose Oxygengas PHOTOSYNTHESIS

  14. Chloroplasts: Sites of Photosynthesis • Photosynthesis • Occurs in chloroplasts, organelles in certain plants • All green plant parts have chloroplasts and carry out photosynthesis • Leaves: most chloroplasts • Green color: from chlorophyll in chloroplasts • The pigments absorb light energy

  15. AN OVERVIEW OF PHOTOSYNTHESIS Light • The light reactions convert solar energy to chemical energy • Produce ATP & NADPH Chloroplast NADP ADP + P Calvin cycle • The Calvin cycle makes sugar from carbon dioxide • ATP generated by the light reactions provides the energy for sugar synthesis • The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose Light reactions

  16. Cellular Respiration • C6H12O6 + 6 O2 => 6 CO2 + 6 H2O + Energy Compare this equation to the equation for photosynthesis. • 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2 How are they the same? How are they different?

  17. This equation is essentially the opposite of photosynthesis. Photosynthesis is a building process, while respiration is a breaking-down process.

  18. Plants produce O2 gas by splitting H2O • The O2 liberated by photosynthesis is made from the oxygen in water (H+ and e-)

  19. Chloroplast • A Photosynthesis Road Map Light Stroma NADP Stack of thylakoids ADP + P Light reactions Calvin cycle Sugar used for  Cellular respiration  Cellulose  Starch  Other organic compounds

  20. Review: Photosynthesis uses light energy to make food molecules • A summary of the chemical processes of photosynthesis Chloroplast Light Photosystem IIElectron transport chains Photosystem I CALVIN CYCLE Stroma Electrons Cellular respiration Cellulose Starch Other organic compounds LIGHT REACTIONS CALVIN CYCLE

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