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Photosynthesis

Revised 6/23/08 The details of photosynthesis are to help students with the bigger picture – don’t test over details, test over concepts and overall targets!. PHOTOSYNTHESIS. Photosynthesis. What is the ultimate source of all energy. energy. energy.

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Photosynthesis

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  1. Revised 6/23/08The details of photosynthesis are to help students with the bigger picture – don’t test over details, test over concepts and overall targets!

  2. PHOTOSYNTHESIS Photosynthesis

  3. What is the ultimate source of all energy

  4. energy energy How does the energy get from the sun into the foods we eat?

  5. Why do we see colors? • The sun sends downs little packets of light energy called: PHOTONS

  6. Why do we see colors? • Photons group together in waves • The waves have different lengths • Each “wavelength” presents itself as a color Photons Wavelengths

  7. Why do we see colors? Plants reflect this color of light. That’s why most plants are GREEN Plant pigments like chlorophyll absorb these colors of light so these colors are not seen. What colors of light would a plant with purple leaves absorb?

  8. What colors are being absorbed and what colors are being reflected? Photos courtesy of flowerpictures.net and picturesof.net

  9. Why do we see colors? • What do we call the compounds that absorb and reflect wavelengths of light? • Which compound reflects the green wavelengths thereby making plants green? • Where would we find this compound?

  10. Chloroplast structure Disks called GRANA contain the pigment CHLOROPHYLL. The liquid portion of a chloroplast is the STROMA

  11. Where do wefind chloroplasts?

  12. Chloroplasts are found in cells of leaves. Chloroplast containing chlorophyll stoma

  13. Review • What is the ultimate source of all energy? • In what form does light energy come to the earth? • What compounds absorbs wavelengths? • How do we see colors? • Where in a leaf do we find pigments?

  14. What process captures the light energy and uses it to make food?

  15. OVERVIEW OF PHOTOSYNTHESIS SUNLIGHT PROVIDES THE ENERGY FOR PHOTOSYNTHESIS PLANTS MAKE GLUCOSE AND OXYGEN PLANTS TAKE IN CO2 AND H2O

  16. light chlorophyll Photosynthesis • What is photosynthesis? • Photosynthesis is the process by which: TAKE IN AND USING MAKE oxygen water PLANTS (producers) glucose carbon dioxide

  17. Dark Reaction Light Reaction Photosynthesis • 2 steps: • Light reactions • Dark reactions (aka Calvin cycle)

  18. A member of the faculty at UC Berkeley since 1937, Melvin Calvin received the 1961 Nobel prize in chemistry for identifying the path of carbon in photosynthesis. The cycle of reactions in the dark phase of photosynthesis was named after him for his work in identifying the processes taking place. Who was Calvin anyway?

  19. Light reaction: Occurs in the grana Must have light light Dark Reaction Dark Reaction LIGHT REACTION Light Reaction grana (chlorophyll) Photosynthesis

  20. Dark reactions (aka Calvin cycle): Occurs in the stroma Occurs in the light and dark DARK REACTION Light Reaction  Dark Reaction Light Reaction  stroma (liquid) Photosynthesis

  21. ENERGY H2O H H Step 1: Light Reactions How does the O2 leave the leaf? light energy reacts with the chlorophyll water is split by the light energy H is kept for the dark reaction O2 is released O2 O2 O2 O2 O H2 O2

  22. + H CO2 C6H12O6 Step 2: Dark Reactions glucose is the product H from the water split in the light reaction is present the reactants H and CO2 combine CO2 enters the chloroplast CO2 How does CO2enter the plant? • AKA: CALVIN CYCLE CO2 CO2 CO2 H H • Other carbohydrates besides glucose may be made in photosynthesis

  23. Dark Reaction Light Reaction Photosynthesis Review • Light reactions: H2O split into H2 + O • Dark reactions: H + CO2 = C6H12O6 O2 H2O C6H12O6 chlorophyll CO2

  24. How would this be written as a chemical equation? What goes in? (the reactants) What comes out? (the products) O2 Dark Reaction Light Reaction H2O C6H12O6 chlorophyll CO2 Photosynthesis Formula H2O CO2 C6H12O6 O2

  25. What’s wrong with this equation? The number of atoms is not equal on both sides of the equation. Balance the equation so that the number of atoms of each element is equal on both sides. one carbon atom reactant 6 carbon atoms product H2O CO2 C6H12O6 O2 Photosynthesis Formula 6 (1) 6 6 • Now balance it as if TWO glucose molecules were being produced.

  26. TRY THIS! • Think-Pair-Share Analyze the relationship between photosynthesis, biogeochemical cycles, and food chains.

  27. What goes in? (the reactants) What comes out? (the products) light chlorophyll • 6CO2 + 6H2O 6O2 + C6H12O6 O2 Dark Reaction Light Reaction H2O C6H12O6 chlorophyll CO2 Photosynthesis Review

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