chapter 10 - Copy - CHAPTER 10: PHOTOSYNTHESIS The Process...

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CHAPTER 10: PHOTOSYNTHESIS The Process that Feeds the Biosphere 1. Distinguish between autotrophic and heterotrophic nutrition. Autotrophs are organisms that are capable of making organic molecules from inorganic material such as the process of plants converting carbon dioxide into glucose during photosynthesis using the energy from the sun. Heterotrophs are incapable of this conversion of inorganic to organic and must obtain their organic compounds from eating or decomposing other organisms. 2. Describe the structure of a chloroplast, listing all membranes and compartments. The chloroplast is a double membrane organelle. It contains an outer and inner membrane with the intermembrane space between the two. Within the intermembrane space is the stroma. Within this space are thylakoid membranes which contain the chlorophyll pigment so the thylaloids are green. Thylakoids are stacked into granum. Within the thylakoids is the thylakoid space. 3. Write a summary equation for photosynthesis. carbon dioxide + water + light-> energy glucose + oxygen + water 4. Explain van Niel's hypothesis and describe how it contributed to our current understanding of photosynthesis. Describe the evidence that supported his hypothesis. Van Niel hypothesized that plants split water as a source of hydrogen and release oxygen as a by-product. For the experiment, 18O was used as a tracer CO2 + 2H2O* CH2O + H2O + O2* OR CO2* + 2H2O CH2O* + H2O* + O2 5. In general terms, explain the role of redox reactions in photosynthesis. Photosynthesis is an endergonic redox process energy is required to reduce carbon dioxide Light is the energy source that boosts potential energy of electrons as they are moved from water to sugar When water is split, electrons are transferred from the water to carbon dioxide, reducing it to sugar The Pathways of Photosynthesis 6. Describe the two main stages of photosynthesis in general terms. Light reactions: Occurs in the thylakoid membranes. Photosystem II: Chlorophyll pigment molecules absorb light energy which excites electrons in the chlorophyll. These electrons are eventually captured by the primary electron acceptor in the reaction center and passed along a short electron transport chain that generates a proton gradient that makes ATP by photophosphorylation. The lost electrons in the chlorophyll molecules are replaced by splitting water which also produces oxygen. Photosystem I: Also absorbs light energy which excites electrons that are eventually picked up by NADP+, an electron shuttle and becomes NADPH. The lost electrons from the pigment molecules are replaced by the electrons coming out of the ETC of photosystem II. 7. Describe the relationship between an action spectrum and an absorption spectrum. Explain why the action spectrum for photosynthesis differs from the absorption spectrum for chlorophyll a . The graph of wavelength versus rate of photsynthesis is the action spectrum and profiles the
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This note was uploaded on 05/22/2011 for the course BIO 6 taught by Professor Lalala during the Spring '11 term at East Los Angeles College.

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chapter 10 - Copy - CHAPTER 10: PHOTOSYNTHESIS The Process...

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