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AP Biology Ch. 10
Photosynthesis
Question | Answer |
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photosynthesis | The conversion of light energy to chemical energy that is stored in glucose or other organic compounds; occurs in plants, algae, and certain prokaryotes |
photophosphorylation | The process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the cholorplast during the light reactions of photosynthesis |
photon | A quantum, or discrete amount of light energy |
photosystem | Light-capturing unit located in the thylakoid membrane, consisting of a reaction cneter surrounded by numerous light-harvesting complexes. There are 2 types of photosystems, I & II;they absorb light best at different wavelengths |
primary electron acceptor | 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 molecules |
photosystem II (PS II) | One of two light-capturing units in a chloropkast's thylakoid membrane; it has two molecules of P680 chlorophyll a at its reaction center |
photosystem I (PS I) | One of two light-capturing units in a chloroplast's thylakoid membrane; it has two molecules of P700 chlorophyl a at its reaction center |
photorespiration | metabolic pathway that concumes O2, realeases CO2, generates no ATP, and decreases photosynthetic output; usually occurs on hot,dry,bright days when stomata close and the O2 concentration in the leaf exceeds that of CO2 |
PEP carboxylase | An enzyme that adds carbon dioxide to phosphoenolpyruvate (PEP) to form oxaloacetate |
autotroph | An organism that obtains organic foor molecules from eating other organisms or substances derived from other organism s. Autotrophs use energy from the sun or from the oxidation of inorganic substances to make organic molecules from inorganic ones |
bundle-sheath cell | A type of photosynthetic cell arranged into tightly packed sheaths aroung the veins of a leaf |
Calvin cycle | the 2nd of 2 major stages in photosynthesis (following the light reaction), involving atmospheric CO2 fixation and reduction of the fixed carbon into carbohydrate |
CAM plant | A plant that uses CAM, an adaption for photosynthesis in arid conditions,first discovered in the family Crassulaceae.CO2 entering open stomata during the night is converted into organic acids,which release CO2 for the Calvin cycle during the day when stom |
carbon fixation | the incorporation of carbon from CO2 into an organic compunf by an autotrphic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote) |
carotenoid | An accesory pigment,either yellow or orange, in the chloroplasts of plants.By absorbing wavelength of ligh that chlorophyll cannot,carotenoids broaden the spectrum of colors that can drive photosynthesis |
chlorophyll | A green pigment located within the chloroplasts of plants. Chloropyll a can participate directly in the light reactions, which convert solar energy to chemical energy |
chlorophyll a | A type of blue-green photosynthetic pigment that participates directly in the light reactions |
chlorophyll b | A type of yellow-green photosynthetic pigment that transfers energy to chlorophyll b |
action spectrum | A graph that depicts the relative effectiveness of different wavelengths of radiation in driving a particular process |
absorption spectrum | The range of a pigment's ability to absorb various wavelengths of light |
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 that Calvin cycle with reactions that incorporate CO2 into a four-carbon compound for the Calvin cycle which supplies CO2 for the Calvin cycle |
cyclic electron flow | `A route of electron flow during the light reactions of photosynthesis that involves only photosystem I and that produces ATP but not NAPDH or oxygen |
electromagnetic spectrum | The entire spectrum of radiation ranging in wavelength from less than a nonometer to more than a kilometer |
crassulacean acid metabolism (CAM) | A type of metabolism in which carbon dioxide is taken in at night and incorporated into a variety of organic acids |
glyceraldehyde-3-phosphate (G3P) | the carb produced directly from the Calvin cycle |
heterotroph | An organism that obtains organic food molecules by eating other organisms or their by-products |
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 |
light-harvesting complex | Complex of proteins associated with pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids) that captures light energy and transfers t to reaction-center pigments in a photosystem |
mesophyll cell | A loosley arranged photosynthetic cell located between the bundle sheath and leaf surface |
mesophyll | The ground tissue of a leaf, sandwhiched between the upper and lower epidermis and specialized for photosynthesis |
NADP+ | Nicotinamide adenine dinucleotide phosphate, an acceptor that temporarily stores energized electrons produced during the light reactions |
noncyclic electron flow | 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+ |
reaction center | complex of proteins associated with 2 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,1 of the chlorophylls donates an e |
rubisco | Ribulose carboxylase, the enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP, or ribulose phosphate) |
stomata | microscopic pores surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant. |
stroma | The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water |
spectrophotometer | An instrument that measures the proportions of light of different wavelengths absorbed and transmitted by a pigment solution |
thylakoid | A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy |
visible light | the portion of the electromagnetic spectrum detected as various colors by the human eye, ranging in wavelength from about 380 nm ro about 750 nm |
wavelength | The distance between crests of waves, such as those of the electromagnetic spectrum |