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17 Cards in this Set
- Front
- Back
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The light reactions of photosynthesis supply the Calvin Cycle with ... |
ATP and NADPH |
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sequence that correctly represents the flow of electrons during photosynthesis? |
H2O --> NADPH --> Calvin Cycle |
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how is photosynthesis similar in C-4 plants and CAM plants? |
In both cases, rubisco is not used to fix carbon initially. |
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a correct distinction between autotrophs and heterotrophs ? |
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic. |
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which does not occur during the Calvin Cycle ?
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release of oxygen |
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In mechanism, photophosphorylation is most similar to |
oxidative phosphorylation in cellular respiration |
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Which process is most directly driven by light energy? |
removal of electrons from chlorophyll molecules |
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How do the reactant molecules of photosynthesis reach the chloroplasts in leaves? |
co2 enters leaves via stomata, and water enters via roots and is carried to leaves through veins. |
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how did the use of an oxygen isotope help elucidate the chemistry of photosynthesis |
using 18-O, a heavy isotope of oxygen, as a label, researchers were able to confirm van nails hypothesis that the oxygen produced during photosynthesis originates in water, not in carbon dioxide |
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calvin cycle requires ATP and NADPH, products of the light reactions. if asserted that light reactions don't depend on the calvin cycle and, with continual light, could just keep on producing ATP and NADPH, how would you respond? |
the light reactions could not keep producing NADPH and ATP without the NADP+, ADP and (P)i that the calvin cycle generates. the two cycles are interdependent |
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what color of light is least effective in driving photosynthesis? Explain |
green, because green light is mostly transmitted and reflected - not absorbed - by photosynthetic pigments |
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compared to a solution of isolated chlorophyll, why do intact chloroplasts release less heat and fluorescence when illuminated? |
in chloroplasts, light-excited electrons are trapped by a primary electron acceptor, which prevents them from dropping back to the ground state. in isolated chlorophyll, there is no electron acceptor, so the photo excited electrons immediately drop down to ground state, with the emission of light and heat. |
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in the light reactions, what is the initial elector donor? where do electrons finally end up? |
water (H2O) is the initial electron donor, NADP+ accepts electrons at the end of the electron transport chain, becoming reduced to NADPH |
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to synthesize one glucose molecule, the calvin cycle uses _____ molecules of CO2, ____molecules of ATP, and _____ molecules of NADPH. |
6 molecules of CO2 18 molecules of ATP 12 molecules of NADPH |
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Explain why the large numbers of ATP and NADPH molecules used during the calvin cycle are constant with the high value of glucose as an energy source. |
the more potential energy a molecule stores, the more energy and reducing power is required for the formation of that molecule. To reduce CO2 to glucose, much energy and reducing power is required in form of large numbers of ATP and NADPH molecules. |
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explain why photorespiration lowers photosynthetic output for plants |
photorespiration decreases photosynthetic output by adding oxygen, instead of carbon dioxide to the calvin cycle |
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the presence of PS1, not PS2, in the bundle-sheath cells of C4 plants has an effect on O2 concentration. -what is that effect, and how might that benefit the plant? |
without PS2, no O2 is generated in bundle-sheath cells. This avoids the problem of O2 competing with CO2 for binding to rubisco in these cells. |
