Harvesting Light Energy
- Photosynthesis -

     The process of photosynthesis is the major gateway for the energy that moves into the ecosystems of our planet. The process converts light energy from the sun into chemical energy in the form of building covalent bonds within organic molecules (mostly). As you may realize this chemical energy (in the form of organic molecules) can be used in cellular respiration. Virtually ALL life forms on our planet depend directly or indirectly on photosynthesis (there are exceptions). Photosynthetic bacteria, algae as well as plants are organisms able to perform photosynthesis. Many non-photosynthetic lifeforms have established relationships with photosynthetic partners. [Do not get too bogged down in the details of this section.]

  1. Why do we discuss photosynthesis in our class?
  2. What is accomplished by the process of photosynthesis?
  3. What kind of organisms perform photosynthesis? Give examples?
  4. These lifeforms are often referred to as producers? Why?
  5. Can animals photosynthesize? Do they depend on photosynthesis?
  6. Coral reefs are produced by animals and depend on light energy. Why is that?
  7. What is the overall formula of photosynthesis? Describe the reactants and the products.
  8. In which organelle does this process take place in algae and plants? In photosynthetic bacteria? In animals?
  9. Describe the structure of the chloroplast. Name the different parts? Which lifeforms have chloroplasts?
  10. What is the difference betweem the light- and the dark reactions? What is accomplished by each?
  11. How does photosynthesis produce sugars? What happens to any excess of sugars produced during photosynthesis?
  12. Where does oxygen come from?
  13. What is the role of the different pigments used in photosynthesis?
  14. What kind of light does chlorophyll absorb?
  15. Why are most plants green?
  16. Are there other pigments than chlorophyll? What is the purpose of these pigments?
  17. Understand how light is a form of energy. Relate visible light to the electromagnetic spectrum. Again, what is the role of pigments in photosynthesis?
  18. Try to summarize (again) what is accomplished in the two processes (light reactions versus the Calvin Cycle). How do they depend upon each other? What is produced? What goes into the cycles?

This simplistic overview gives you an idea about the two main pathways of photosynthesis. What is accomplished in each of them? To the right is a more detailed overview incorporating the major energy carrying molecules involved. [Note: the dark reactions are often referred to as the  Calvin Cycle after its discovererers].

  1. What is the ecological and evolutiuonary importance of photosynthesis in biological systems?

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Page created by: Peter Svensson
Updated: February 28,  2007