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Description
Flashcards by Nicholas Haddad, updated more than 1 year ago
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Created by Nicholas Haddad
over 7 years ago
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| Question | Answer |
| What is the purpose of photosynthesis? | Photosynthesis is a process that plants use to create sugars by using energy collected by sunlight. |
| Describe the structure and functions of the chloroplast and its parts. | The chloroplast has an outer and inner membrane, both phospholipid bilayers, that regulate the flow of materials into and out of the organelle. Inside, thylakoids, flattened sacs that contain pigments, are found in stacks called grana. Surrounding the thylakoids, the storm contains enzymes, DNA and RNA (of the chloroplast). The chloroplast is the organelle that houses the reactions of photosynthesis. |
| Explain the importance of light to photosynthesis. Which light waves are best/least absorbed? Why do we see plants as green? | Pigments are light absorbing substances. They absorb light and release energy that powers the transport of electrons and produces necessary molecules for the production of sugars. Plants contain a lot of chlorophyll, a pigment that reflects green and absorbs all other colors. This is why most plants appear green. In photosynthesis, red/orange and blue/violet waves are the best absorbed, while green isn't absorbed as much. Therefore, red/orange and blue/violet (higher energy-better) are more efficient and better used. |
| What are the three energy conversions in the process of photosynthesis? | The three energy conversions in the process of photosynthesis are: 1. Absorption of light energy 2. Conversion of light to chemical energy 3. Storage of chemical energy in the form of sugars |
| What is the overall chemical formula for photosynthesis? | light 3H2O + 3CO2 -------> C3H6O3 + 3H2O chlorophyll |
| Explain the light reactions of photosynthesis. Where do they occur? What go into and out of the reactions? What role do photosystems have? How are the ATP molecules formed? | The Light Reactions of Photosynthesis occur in the thylakoid membranes. Here, light enter PS2 and is funneled to the reaction center, where electrons are transported through a system to PS1. The electrons lost in PS2 are replaced by oxidizing water into protons, electrons and O2 which is released, using solar energy. The electrons replace those lost in PS2, and the protons are actively transported into the thylakoid using solar energy from the electron transfers. Here, potential energy builds up, and the protons diffuse out through ATP Synthase, an enzyme complex that combines ADP and P to form ATP. The protons and electrons, now out of the electron transport system, reduce NADP+ to form NADPH, an electron and hydrogen carrier. The reactants are light, H2O, ADP and P and NADPH. The products are O2, NADPH and ATP (used in the Calvin cycle) |
| Explain the Calvin Cycle. What goes into and out of the reactions? Where do these materials come from? Where does this reaction occur? Is the Calvin Cycle dependent on light? | The Calvin cycle occurs in the storm. CO2 is fixed to a molecule of RuBP, a 5 carbon sugar, forming a 6-C sugar which splits, forming 2 3-C PGA's. By the hydrolysis of ATP and the donation of H's from NADPH, PGAL is formed. For every 6 molecules of PGAL, one is released and used for food, carbon skeletons and other cellular processes. The remaining 5, through a series of enzymatic reactions and the donation of a P from ATP, are turned back into RuBP. The reactants are RuBP, CO2, ATP and NADPH. The products are NADP+, ADP and P, PGAL and RuBP. The Calvin cycle isn't light dependent, but depends on materials produced in the light reactions. |
| What factors influence photosynthesis? | Photosynthesis is influenced by light intensity, CO2 levels, temp., O2 levels and water, along with other limiting factors. As light intensity increases to a certain point (light saturation point), the rate of photosynthesis increases. Past that, the rate levels out. Too much light can damage cells, causing photo inhibition. Temp. is optimal in a certain range, and looks like a parabola on a graph. CO2 acts like light intensity, except it doesn't affect the cell past the CO2 saturation point. Water acts like temp. As O2 levels increase, the rate of photosynthesis decreases. |
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