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31 Cards in this Set
- Front
- Back
Photosynthesis |
- energy in light is captured and used to make carbs - CO2 is reduced - H2O is oxidized - energy from light drives reaction |
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Heterotroph |
must eat food to sustain life |
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Autotroph |
makes organic molecules from inorganic sources |
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Photoautotroph |
light used as a source of energy |
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Chloroplast |
- organelle in which photosynthesis occurs - Co2 enters and O2 exits leaf through pores called stomata |
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Chlorophyll |
green, photosynthetic pigment |
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Thykaloid membrane |
contains plant pigments |
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Thykaloids |
flattened, fluid-filled tubules |
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Granum |
stack of thykaloids |
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Stroma |
region between thykaloid and inner membranes |
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About Photosynthetic Pigments |
-having different pigments allows plants to absorb light at many different wavelengths - after electrons absorb energy the become excited and unstable - excited electrons are transferred to a more stable molecule |
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Photosynthetic Pigments |
- chlorophyll - carotenoids |
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Chlorophyll |
- Chlorophyll (a) (primary photosynthetic pigment) - Chlorophyll (b) - both found in green plants and algae |
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Carotenoids |
- yellow, red, orange, etc. pigments in leaves - masked by the amount of chlorophyll in warmer seasons - lower temp = less chlorophyll and more carotenoids showing - different pigments give a larger range of light absorption |
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Stages of Photosynthesis |
- Light Reactions - Noncyclic Electron Flow - Cyclic Electron Flow |
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Light Reactions |
- pigments get energy from sunlight - ATP, NADH, and O2 are generated - oxidizes water |
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Photosystem |
light-energy harvesting system - Photosystem I (PSI) - Photosystem II (PSII) - light excites pigments in both of these |
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Photosystem II |
- 1st step in photosynthesis - excited electrons travel from here to PSI - electrons pass thru ETC and release energy |
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Photosystem I |
- occurs after PSII - primary NADPH maker |
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How is H+ Gradient Made? |
- increase [H+] in thykaloid lumen by splitting of water - or increase [H+] by ETC pumping H+ into lumen - or decrease [H+] in stroma from formation of NADPH |
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Products of Light Reactions |
- Oxygen made in thykaloid lumen by oxidation of H2O - NADPH made in stroma from electrons that are boosted in PSI - ATP made in stroma |
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Noncyclic Electron Flow |
- light excites electrons in pigment molecules - excited electrons pass linearly from PSII to PSI - NADP+ reducted to NADPH
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Cyclic Electron Flow |
- makes only ATP - PSI electrons excited, release energy and return to PSI |
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Steps of the Clavin Cycle |
- Carbon Fixation - Reduction Phase and Carb Synthesis - Regeneration of RuBP |
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Calvin Cycle |
- uses more ATP than NADPH - CO2 incorporated into carbs - requires A LOT of energy. - reduction by NADPH |
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Carbon Fixation |
- CO2 incorporated into RubP (5-carbon sugar) - requires rubisco - product: 6-carbon molecule that splits into two 3-PG |
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Reduction and Carbs Synthesis Phase |
-ATP and NADPH are used to convert 3PG to G3P - 12 G3P molecules made in this step |
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Regeneration of RuBP |
- keeps Calvin Cycle running |
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Environmental Factors Affecting the Calvin Cycle |
- light intensity - temperature - water availability |
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C4 Plants |
- have mechanism to minimize photorespiration - C4 plants make oxalacetate (4-carbon molecule) - leaves have two-cell layer organization |
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C3 vs. C4 |
- warm and dry climates: C4 plants - cooler climates: C3 plants use les energy to fix CO2 - 90% of plants are C3 |