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| 40013229 | Mesophyll | The tissue in the interior of the leaf, in which chloroplasts are found | 0 | |
| 40013230 | Stomata | Pore-like openings in leaves that allows CO2 to enter the leaf and O2 to exit | 1 | |
| 40013231 | Stroma | Dense fluid within the chloroplast | 2 | |
| 40013232 | Thylakoids | Interconnected membranous sacs that separate stroma from the thylakoid space | 3 | |
| 40013233 | Chlorophyll a | Blue-green pigment | 4 | |
| 40013234 | Chlorophyll b | Green-yellow accessory pigment | 5 | |
| 40013235 | Chlorophyll | Green pigment located in the thylakoid membrane | 6 | |
| 40013236 | 6 CO2 + 12 H2O + light energy --> C6H12O6 + 6O2 + 6 H2O | Equation of photosynthesis | 7 | |
| 40013237 | C.B. van Niel | Discovered that plants split water as a source of electrons from hydrogen atoms, and oxygen is a byproduct | 8 | |
| 40013238 | Light reactions | The reactions of photosynthesis that convert solar energy to chemical energy | 9 | |
| 40013239 | NADP+ | Electron acceptor that temporarily stores energized electrons in light reactions | 10 | |
| 40013240 | Photophosphorylation | The addition of a phosphate to ADP through chemiosmosis | 11 | |
| 40013241 | Calvin cycle | Makes sugars, but requires light reactions to provide the energy | 12 | |
| 40013242 | Carbon fixation | The incorporation of carbon dioxide into organic compounds | 13 | |
| 40013243 | NADPH | Reduces the fixed carbon of light reactions to carbohydrate; reduces 1,3 biphosphoglycerate into G3P in the Calvin cycle | 14 | |
| 40013244 | Light | Electromagnetic energy | 15 | |
| 40013245 | Wavelength | Distance between the crests of electromagnetic waves | 16 | |
| 40013246 | Electromagnetic spectrum | Entire range of radiation | 17 | |
| 40013247 | Visible light | segment of the electromagnetic spectrum visible to the human eye; detected as color; drives photosynthesis | 18 | |
| 40013248 | Photons | Light behaves as though it consists of discrete particles; have a fixed quantity of energy inversely related to the wavelength of the light | 19 | |
| 40013249 | Pigments | Substances that absorb visible light | 20 | |
| 40013250 | Spectrophotometer | Measures the ability of a pigment to absorb various wavelengths of light | 21 | |
| 40013251 | Absorption spectrum | The graph plotting a pigment's light absorption | 22 | |
| 40013252 | Action spectrum | profiles the effectiveness of different wavelengths of radiation; demonstrated by Theodor W. Engelmann | 23 | |
| 40013253 | Carotenoids | Yellow-orange accessory pigments; absorb and dissipate excessive light energy that could damage chlorophyll or interact with oxygen | 24 | |
| 40013254 | Ground state | When the electron is in its normal orbital, the pigment molecule is in this state | 25 | |
| 40013255 | Excited state | When the electron is excited by light and moves up a level, the pigment molecule is in this state; unstable | 26 | |
| 40013256 | Fluorescence | Afterglow given off by isolated pigments as electrons fall back to their ground state | 27 | |
| 40013257 | Photosystem | A reaction center surrounded by a number of light-harvesting complexes; converts light energy to chemical energy that will be used in the synthesis of sugar | 28 | |
| 40013258 | Light-harvesting complex | Consists of pigment molecules bound to particular proteins; acts as an antenna for the reaction center | 29 | |
| 40013259 | Reaction center | Protein complex that includes two special chlorophyll a molecules and the primary electron acceptor | 30 | |
| 40013260 | Reaction center chlorophyll a | Their molecular environment enables them to use the energy from light to boost one of their electrons to a higher energy level | 31 | |
| 40013261 | Primary electron acceptor | Captures chlorophyll a electrons as soon as they are excited | 32 | |
| 40013262 | Photosystem II | First photosystem that functions in light reactions; its reaction center is called P680 | 33 | |
| 40013263 | Photosystem I | Second photosystem that functions in light reactions; its reaction center is called P700 | 34 | |
| 40013264 | Noncyclic electron flow | Predominant route of electron flow through the photosystems; a photon of light strikes a pigment molecule in a light-harvesting complex and bounces from pigment molecule to pigment molecule until it reaches one of the two P680 chlorophyll a molecules in the PS II reaction center. It excites one of the P680 electrons to a higher energy state. An enzyme splits a water into two electrons, to protons, and an oxygen atom. Electrons are sent to replenish the P680 molecules and the oxygen atom combines with another one, forming O2. Each photoexcited electron passes down an ETC to PS I, and the exergonic "fall" of electrons provides energy for the synthesis of ATP. Meanwhile, light energy was transferred to the PS I reaction center, exciting an electron of one of two P700 chlorophyll a molecules. The electron was captured by PS I's primary electron acceptor, and the hole left in the P700 is filled by an electron from the ETC. Photoexcited electrons are then passed from PS I's primary electron acceptor down a second ETC through the protein ferredoxin (Fd). The enzyme NADP+ reductase transfers two electrons from Fd to NADP+, reducing it to NADPH. Pushes electrons from water, where they are at a low state of potential energy, to NADPH, where they have lots of potential energy. The light-driven electron current also generates ATP. | 35 | |
| 40013265 | Plastiquinone (Pq) | Cytochrome complex electron carrier in the ETC between PS II and PS I | 36 | |
| 40013266 | Plastocyanin (Pc) | Protein in the ETC between PS II and PS I | 37 | |
| 40013267 | Ferredoxin (Fd) | Protein in the ETC of PS I | 38 | |
| 40013268 | NADP+ reductase | Transfers two electrons from Fd to NADP+ | 39 | |
| 40013269 | Cyclic electron flow | Occurs solely in PS I. Electrons cycle back from Fd to the cytochrome complex Pq and the protein Pc and from there continue on to a P700 chlorophyll in the reaction center. No production of NADPH, no release of oxygen. Produces ATP. | 40 | |
| 40013270 | Similarities between chemiosmosis in chloroplasts and mitochondria | An ETC assembled in a membrane pumps protons across the membrane and transforms redox energy to a proton-motive force; built into this membrane is ATP synthase, whose cytochromes are very similar in chloroplasts and mitochondria | 41 | |
| 40013271 | Differences between chemiosmosis in chloroplasts and mitochondria | Mitochondria transfer chemical energy from food to molecules of ATP and NADH, while chloroplasts transform light energy into chemical energy in ATP and NADPH; the inner membrane of the mitochondrion pumps protons from the mitochondria matrix out to the intermembrane space, and they diffuse back into the matrix to power ATP synthase, while in the thylakoid membrane, protons are pumped from the stroma into the thylakoid space, and ATP is made as the hydrogen ions diffuse down their concentration gradient out to the stroma | 42 | |
| 40013272 | Steps that contribute to the proton gradient in photosynthesis | Water is split by PS II on the side of the membrane facing the thylakoid space; Pq transfers electrons to the cytochrome complex and protons are translocated across the membrane into the thylakoid space; a hydrogen ion is removed from the stroma when it is taken up by NADP+ | 43 | |
| 40013273 | Calvin cycle | The anabolic pathway that uses ATP and NADPH to convert CO2 to sugar. For a net synthesis of one G3P, the Calvin cycle consumes nine molecules of ATP and six molecules of NADPH | 44 | |
| 40013274 | Similarities between Calvin cycle and Krebs cycle | A starting material is regenerated after molecules enter and leave | 45 | |
| 40013275 | Differences between Calvin cycle and Krebs cycle | Krebs cycle is catabolic, Calvin cycle is anabolic; Calvin cycle uses NADPH, Krebs cycle produces NADH; Calvin cycle uses ATP, Krebs cycle creates it | 46 | |
| 40013276 | Three phases of the Calvin cycle | Carbon fixation, reduction, regeneration of the CO2 acceptor | 47 | |
| 40013277 | G3P | Glyceraldehyde-3-phosphate; the sugar produced in the Calvin cycle. For the net synthesis of one molecule of G3P, the cycle must fix three molecules of carbon dioxide, and thus take place three times. Becomes the starting material for metabolic pathways that synthesize other organic compounds, including glucose. | 48 | |
| 40013278 | Carbon fixation | The Calvin cycle attaches each carbon dioxide molecule to a 5C sugar called RuBP, in a reaction catalyzed by rubisco. The product of this reaction is a 6C intermediate so unstable that it immediately splits in half, forming two molecules of 3-phosphoglycerate for each CO2 molecule, or six total. | 49 | |
| 40013279 | Rubisco | Enzyme that attaches carbon dioxide molecule to 5C RuBP; the most abundant protein on earth | 50 | |
| 40013280 | Reduction | Each molecule of 3-phosphoglycerate receives a phosphate from ATP, becoming 1,3-biphosphoglycerate. A pair of electrons donated from NADPH then reduces the 1,3-biphosphoglycerate into G3P. Each 1,3-biphosphoglycerate also loses a phosphate group. At this point, one of the G3P molecules leaves the cycle to be used by the cell, but the other five must be recycled to regenerate the three molecules of RuBP. | 51 | |
| 40013281 | Regeneration of the CO2 acceptor (RuBP) | The carbon skeletons of the five G3P are rearranged into three molecules of RuBP using energy from three molecules of ATP | 52 | |
| 40013282 | Transpiration | The loss of water from leaves | 53 | |
| 40013283 | C3 plants | Average plants in which the initial fixation of carbon occurs via rubisco. So named because the first organic product of carbon fixation is the 3C compound 3-phosphoglycerate. When their stomata close on hot days, they produce less sugar, and the declining level of CO2 in the leaf starves the Calvin cycle. | 54 | |
| 40013284 | Photorespiration | Rubisco binds to O2 in place of CO2. The product splits, and a 2C compound leaves the chloroplast. Peroxisomes and mitochondria rearrange and split this compound, releasing CO2. Consumes ATP without generating it and produces no sugar. | 55 | |
| 40013285 | C4 plants | Plants that preface the Calvin cycle with an alternate mode of carbon fixation that forms a 4C compound as its first product. Advantageous in hot regions with intense sunlight, where stomata partially close during the day. | 56 | |
| 40013286 | Bundle-sheath cells | C4 photosynthetic cells tightly packed around the veins of the leaf where the Calvin cycle takes place | 57 | |
| 40013287 | Mesophyll cells | Located between the bundle-sheath cells and the leaf surface, pump CO2 into the bundle sheath, keeping the CO2 concentration there high enough for rubisco to bind to carbon instead of oxygen. | 58 | |
| 40013288 | C4 pre-Calvin cycle | PEP carboxylase, which has a higher affinity for CO2 than rubisco and no affinity for O2, incorporates CO2 with PEP, forming the 4C oxaloacetate in the mesophyll cells. After the carbon fixation, the mesophyll cells export their 4C products to the bundle-sheath cells through plasmodesmata. Within the bundle-sheath cells, 4C compounds release CO2, which then goes to the Calvin cycle. Pyruvate is also regenerated for conversion to PEP in mesophyll cells | 59 | |
| 40013289 | CAM plants | Crassulacean acid metabolism; a mode of carbon fixation in which stomata are closed during the day and opened at night. The mesophyll cells of CAM plants store the organic acids they make during the night in their vacuoles until morning, when the stomata close. During the day, when the light reactions can supply ATP and NADPH for the Calvin cycle, CO2 is released from the organic acids made the night before to become incorporated into the sugar in the chloroplasts. | 60 | |
| 40013290 | Similarities between C4 pathway and CAM pathway | Carbon dioxide is incorporated into organic intermediates before it enters the Calvin cycle | 61 | |
| 40013291 | Differences between C4 pathway and CAM pathway | In C4 plants, the initial steps of carbon fixation are separated structurally from the Calvin cycle (mesophyll cells and bundle-sheath cells). In CAM plants ,the two steps occur at separate times (day and night) but both within the same cell (mesophyll) | 62 |
