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| The range of a pigment’s ability to absorb various wavelengths of light. |
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| A graph that depicts the relative effectiveness of different wavelengths of radiation in driving a particular process. |
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| An organism that obtains organic food molecules without eating other organisms or substances derived from other organisms. Autotrophs use energy from the sun or from the oxidation of inorganic substances to make organic molecules from inorganic ones. |
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| A type of photosynthetic cell arranged into tightly packed sheaths around the veins of a leaf. |
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| A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate. |
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| A plant that prefaces the Calvin cycle with reactions that incorporate CO2 into a four-carbon compound, the end product of which supplies CO2 for the Calvin cycle. |
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| The second of two major stages in photosynthesis (following the light reactions), involving atmospheric CO2 fixation and reduction of the fixed carbon into carbohydrate. |
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| A plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions, first discovered in the family Crassulaceae. Carbon dioxide entering open stomata during the night is converted into organic acids, which release CO2 for the Calvin cycle during the day, when stomata are closed. |
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| The incorporation of carbon from CO2 into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic bacterium). |
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| An accessory pigment, either yellow or orange, in the chloroplasts of plants. By absorbing wavelengths of light that chlorophyll cannot, carotenoids broaden the spectrum of colors that can drive photosynthesis. |
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| A type of blue-green photosynthetic pigment that participates directly in the light reactions. |
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| A type of yellow-green accessory photosynthetic pigment that transfers energy to chlorophyll a. |
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| A route of electron flow during the light reactions of photosynthesis that involves only photosystem I and that produces ATP but not NADPH or oxygen. |
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| glyceraldehyde-3-phosphate (G3P) |
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| The carbohydrate produced directly from the Calvin cycle. |
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| An organism that obtains organic food molecules by eating other organisms or their by-products. |
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| The steps in photosynthesis that occur on the thylakoid membranes of the chloroplast and that convert solar energy to the chemical energy of ATP and NADPH, evolving oxygen in the process. |
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| The ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis. |
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| Nicotinamide adenine dinucleotide phosphate, an acceptor that temporarily stores energized electrons produced during the light reactions. |
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| A route of electron flow during the light reactions of photosynthesis that involves both photosystems and produces ATP, NADPH, and oxygen. The net electron flow is from water to NADP+. |
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| A quantum, or discrete amount, of light energy. |
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| The process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis. |
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| A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; generally occurs on hot, dry, bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide. |
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| The conversion of light energy to chemical energy that is stored in glucose or other organic compounds; occurs in plants, algae, and certain prokaryotes. |
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| Light-capturing unit located in the thylakoid membrane of the chloroplast, consisting of a reaction center surrounded by numerous light-harvesting complexes. There are two types of photosystems, I and II; they absorb light best at different wavelengths. |
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| primary electron acceptor |
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Definition
| A specialized molecule sharing the reaction center with the pair of reaction-center chlorophyll a molecules; it accepts an electron from one of these two chlorophylls. |
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| Complex of proteins associated with two special chlorophyll a molecules and a primary electron acceptor. Located centrally in a photosystem, this complex triggers the light reactions of photosynthesis. Excited by light energy, one of the chlorophylls donates an electron to the primary electron acceptor, which passes an electron to an electron transport chain. |
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| Ribulose carboxylase, the enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP, or ribulose bisphosphate). |
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| A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant. |
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