Chapter 7: Photosynthesis
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27 terms
Terms | Definitions |
|---|---|
 absorption spectrum | the spectrum of electromagnetic radiation that has passed through a medium that absorbed radiation of certain wavelengths |
| action spectrum | A graph that depicts the relative effectiveness of different wavelengths of radiation in driving a particular process. |
| ATP synthase | large protein that uses energy from H+ ions to bind ADP and a phosphate group together to produce ATP; functions in the production of ATP in chloroplasts and mitochondria |
| autotroph | organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer |
| C3 plant | 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. |
| C4 plant | 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. |
| Calvin cycle reactions | Portion of photosynthesis that takes place in the stroma of chloroplasts and can occur in the dark; it uses the products of the light reactions to reduce CO2 to a carbohydrate. |
| CAM | 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. |
| carbon dioxide fixation | The transfer of carbon dioxide to organic compounds |
| carotenoid | An accessory pigment, either yellow or orange, in the chloroplasts of plants. By absorbing wavelengths of light that chlorophyll cannot, they broaden the spectrum of colors that can drive photosynthesis. |
| chemiosmosis | An energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP. Most ATP synthesis in cells occurs by chemiosmosis. |
| chlorophyll | A green pigment located within the chloroplasts of plants. Chlorophyll a can participate directly in the light reactions, which convert solar energy to chemical energy. |
| chloroplast | An organelle found only in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide to water. It consists of an inner and outer membrane, a thylakoid and thylakoid membrane, and stroma. |
| cyclic electron pathway | Portion of the light reactions of photosynthesis that generates ATP using only photosystem I |
| electron transport chain | A sequence of electron carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP. |
| grana | a stack of thylakoids within a chloroplast |
| heterotroph | organism that obtains energy from the foods it consumes; also called a consumer |
| light reactions | 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. |
| noncyclic electron pathway | Involves both Photosystems I and II. It produces ATP and NADPH (coenzyme). It uses H2O as the source of protons and is always present int he cyclic pathway, but this one is longer and more complicated and produces more ATP |
| photorespiration | 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. The enzyme RuBP carboxylase fixes oxygen instead of carbon dioxide. |
| photosynthesis | process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches |
| photosystem | in the thylakoid membranes of chloroplasts, a cluster of chlorophyll and other pigment molecules that harvest light energy for the light reactions of photosynthesis |
| RuBP carboxylase | enzyme that starts the Calvin cycle by catalyzing attachment of carbon atom from CO2 to RuBP |
| stomata | Pore-like openings in leaves that allow gases (CO2 and O2) and water to diffuse in and out of the leaves. |
| stroma | The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water. Part of dark reactions during photosynthesis. |
| thylakoid | A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy. Part of light reactions during photosynthesis. |
| visible light | That portion of the electromagnetic spectrum detected as various colors by the human eye, ranging in wavelength from about 380 nm to about 750 nm. |
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