Term
| What is the chemical equation of photosynthesis? |
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Definition
6CO2 + 12H2O -> C6H12O6 + 6H2O + 6O2
REVERSE OF RESPIRATION |
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Term
| Who carries out oxygenic photosynthesis? |
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Definition
Cyanobacteria
Algae
Terrestrial Plants (chloroplasts) |
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Term
| What is the site of photosynthesis? |
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Definition
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Term
| ____________ membranes contain chlorophyll and other pigments clustered into photosynthesis. |
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Definition
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Term
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Definition
| the stacks of thylakoids embedded in the stroma of a chloroplast. |
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Term
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Definition
| semiliquid substance surrounding the thykaloid membrane that houses enzymes needed to assemble organic molecules from CO2 using energy from ATP coupled with reduction of NADPH. |
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Term
| What are light dependent reactions? |
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Definition
| Require light captured from sunlight and make ATP and reduce NADP+ to NADPH |
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Term
| What are light INdependent reactions? (Carbon fixators) |
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Definition
| Does not require light DIRECTLY. Uses ATP and NADPH to synthesize organic molecules from CO2 |
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Term
| What happens in the light dependent reactions? |
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Definition
| Photosystems in the thykaloid absorb photons of light and use this energy to create ATP and NADPH. Electrons lost from the photosystems are replaced by the oxidation of water, producing O2 as a by-product. The ATP and NADPH produced by the light reactions is used during carbon fixation in the Calvin cycle in the stroma. |
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Term
| What did Helmont discover? |
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Definition
| Plants gain weight, more than just root uptake. |
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Term
| What did Priestly discover? |
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Definition
| PLants release something to restore air. |
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Term
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Definition
| Photosynthesis splits co2 and releases Oxygen |
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Term
| What did Blackman discover? |
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Definition
| Photosynthesis occurs in 2 stages: light dependent vs. independent using enzymes |
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Term
| What did van niel propose? |
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Definition
CO2 + H2A + light energy -> CH2O + H2O + 2A
Later, water was identified as the source of the O2 released from photosynthesis. Robin hill confirmed that energy from light reactions fuels carbon fixation. |
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Term
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Definition
| Molecules that absorb light energy in the visible range. |
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Term
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Definition
| Particle of light that acts as a discrete bundle of energy. The energy content of a photon is inversely proportional to the wavelength of light. |
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Term
| What is the photoelectric effect? |
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Definition
| Removal of an electron from a molecule of light. |
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Term
| The color blue is the _________ amount of energy and red is _________. |
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Definition
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Term
| What are the 2 things that happens when a photon strikes a molecule? |
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Definition
| It's energy is either lost as heat or absorbed by the electrons of the molecle which puts said electrons in a higher energy level |
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Term
| What is the absorption spectrum? |
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Definition
| range and efficiency of photons molecule is capable of absorbing |
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Term
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Definition
| Main pigment in plants and cyanobacteria that is the ONLY pigment that can act directly to convert light energy to chemical energy. It absorbs violet-blue and red light. |
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Term
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Definition
| Accessory pigment or secondary pigment absorbing light wavelengths that chlorophyll a does not absorb. |
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Term
| What is the structure of chlorophyll? |
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Definition
| Porphyrin ring - complex ring that has alternating double and single bonds that has magnesium in the center of the group. SIMILAR TO HEME |
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Term
| What do photons do the electrons of the porphyrin ring? |
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Definition
| Excite the electrons and are shuttled away from the ring. |
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Term
| What is the action spectrum? |
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Definition
| Relative effectiveness of different wavelengths of light in promoting photosynthesis. Corresponds to the absorption spectrum for chlorophylls |
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Term
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Definition
| Can absorb a wide range of energies and scavenge free radicals. It is an antioxidant. Same structure as cholorphyll. |
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Term
| What is phycobiliprotein? |
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Definition
| Important in low-light ocean areas. |
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Term
| What is the antenna complex? |
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Definition
| Hundred of accessory pigment molecules that gather photons and feeds the captured light energy to the reaction center. |
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Term
| What is the reaction center that the antenna complex feeds its gathered photons to? |
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Definition
| Includes 1 or more chlorophyll a molecules and passes the excited electrons out of the photosystem and into the electron acceptor. |
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Term
| What does the energy from the antenna complex cause? |
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Definition
| The energy transferred causes the electron to become excited and is then transferred to the electron acceptor. Water then donates an electron to cholorphyll A to replace the one it just lost to the electron acceptor. |
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Term
| What is the 1st step of the light-dependent reaction? |
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Definition
1.) Primary photoevent
A photon of light is captured by a pigment molecule |
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Term
| What is the 2nd step of the light-dependent reaction? |
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Definition
2.) Charge separation
Energy is transferred to the reaction center; an excited electron is transferred to an acceptor molecule |
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Term
| What is the 3rd step of the light-dependent reaction? |
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Definition
3.) Electron transport
Electrons move through carriers to reduce NADP+ |
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Term
| What is the 4th and final step of the light-dependent reaction? |
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Definition
4.) Chemiosmosis
This is where ATP is produced |
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Term
| What is cyclic photophosphorylation? NO OXYGEN |
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Definition
| Where one photosystem is used. Anoxygenic photosynthesis. The excited electron is passed to the electron transport chain and this generates a proton gradient for ATP synthesis. Once ATP is created, the electron is transferred to another acceptor and then back to the reaction center to start again. |
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Term
| In oxygenic photosynthesis, what are the two photosystems that are connected? |
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Definition
| Photosystem II which can generate an oxidation potential high enough to oxidize water, and Photosystem I which functions somewhat like sulfur bacteria. |
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Term
| What happens when the two photosystems work together? |
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Definition
| They carry out NONCYCLIC transfer of electrons that is used to generate ATP and NADPH. |
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Term
| What is the process of noncyclic oxygenic photosynthesis? |
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Definition
PHOTOSYSTEM II IS FIRST!
1.) Accessory pigments shuttle energy to the P680 rxn cntr
2.) Excited electrons from P680 are transferred to b6-f
3.) Electrons lost are replaced by an electron released from the splitting of water.
PHOTOSYSTEM I IS SECOND
4.) Receives energy from antenna complex
5.) Energy is shuttled to P700 rxn center
6.) Excited electron is transferred to a membrane-bound electron carrier
7.) Passes electrons to NADP+ to form NADPH
8.) Accepts electrons from plastocyanin to replace those donated to NADP+ |
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Term
| What is the b6-f complex? |
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Definition
| Series of electron carriers that are embedded in the thykaloid membrane. Protons are pumped into the thylakoid space to form a proton gradient. |
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Term
| Where is ATP synthase embedded? |
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Definition
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Term
| How does chemiosmosis occur? |
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Definition
| The protons that were produced during oxygenic photosynthesis are accumulated in the thylakoid space, they move into the stroma ONLY through ATP synthase. ATP is then produced from ADP + P1. |
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Term
| How do cells produce carbohydrates? |
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Definition
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Term
| What energy drives the calvin cycle? |
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Definition
| That obtained from the light-dependent rxns. Can be cyclic or noncyclic. Drives endergonic reaction. |
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Term
| What is the reduction potential? |
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Definition
| a measure of the tendency of a chemical species to acquire electrons and thereby be reduced. |
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Term
| What is the source of protons and energetic electrons? |
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Definition
| NADPH from photosystem 1. |
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Term
| Who is the calvin cycle named after? What is another name for it? Where does it occur? What does it use? |
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Definition
Melvin Calvin.
Also called C3 Photosynthesis.
Biochemical pathway that allows for carbon fixation.
Occurs in stroma.
Uses NADPH and ATP. |
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Term
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Definition
| Incorporation of Co2 into organic molecules that occurs in the first step of the calvin cycle. |
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Term
| Ribulose-bis-phosphate (5C) + CO2 -> 2PGA (3C) |
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Definition
| This rxn is catalyzed by ribulose bisphosphate carboxylase/oxygenase AKA RUBISCO. |
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Term
| What are the 3 phases of the Calvin Cycle? |
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Definition
1.)Carbon Fixation
2.)Reduction
3.)Regeneration of RuBP |
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Term
| What happens in the first phase of the calvin cycle? |
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Definition
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Term
| What happens in the 2nd stage of the calvin cycle? |
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Definition
| PGA is reduced (gain electrons) to G3P |
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Term
| What happens in the 3rd stage in the calvin cycle? |
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Definition
| PGA is used to regenerate RuBP. |
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Term
| 3 turns around the calvin cycle incorporate enough carbon to produce a new moleucle of ______? |
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Definition
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Term
| 6 turns around the calvin cycle incorporate enought carbon to synthesize a new molecule of _______? |
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Definition
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Term
| What is the breakdown of energy supplied to the calvin cycle? |
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Definition
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Term
| Is glucose a direct product of the calvin cycle? |
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Definition
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Term
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Definition
| A three carbon sugar used to form sucrose. |
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Term
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Definition
| A major transport sugar in plants. its a dissacharide made of frutose and glucose. |
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Term
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Definition
| Starch - insoluble glucose polymer. Stored for later use. |
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Term
| Photosynthesis uses the products of _______ as starting substrates and respiration uses the products of ______ as its starting substrates. |
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Definition
| Respiration/Photosynthesis |
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Term
| What are the 2 enzymatic activites of Rubisco? |
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Definition
| Carboxylation and Oxidation |
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Term
| What is carboxylation of rubisco? |
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Definition
| Addition of CO2 to RuBP. Favored under normal conditions |
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Term
| What is oxidation of rubisco? (photorespiration) |
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Definition
| Addition of O2 to RuBP. Favored when stomata are closed in hot conditions (low CO2 and high O2) |
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Term
| What competes for the active site on rubisco? |
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Definition
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Term
| Under hot conditions, leaves lose water by evaporation through openings in the leaves (stomata). The stomata close to conserve water but as a result, O2 builds up inside the leaves and CO2 cannot enter the leaves. |
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Definition
| Conditions favoring photorespiration. |
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Term
| What is C3 photosyntehsis? |
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Definition
| Plants that fix carbon using only the calvin cycle |
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Term
| What is C4 and CAM photosynthesis? |
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Definition
| Add CO2 to PEP to form 4 carbon molecule. Uses the enzyme PEP carboxylase. It has a greater affinity for CO2 so there is no oxygenase activity. |
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Term
| C4 is the ________ solution and CAM is ________ solution. |
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Definition
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Term
| What is the C3 pathway vs C4/CAM? |
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Definition
C3 - all reactions occur in the mesophyll cells using CO2 that diffuses in through stomata.
C4/CAM - Incorporates CO2 into a 4 carbon molecule of malate in mesophyll cells. Then transported to sheath cells where it is converted back into CO2 and pyruvate. |
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Term
| What does the anatomy of the c4 plant allow? |
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Definition
| Spatial separation of rubisco from o2 production. The calvin cycle and o2 production are separated in space. |
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Term
| What is the benefit of this anatomy? What is the cost? |
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Definition
Benefit: minimizes photorespiration losses.
Cost: Uses ATP |
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Term
| What are some ex of C4 plants? |
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Definition
| Corn, sugarcane, sorghum, and other grasses. |
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Term
| C4 plant cells initially fix carbon using what? |
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Definition
| PEP carboxylate in mesophyll cells. |
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Term
| What does the carbon fixated to the PEP cbxylse produce? What is that converted to? |
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Definition
| Produces oxaloacetate (4C) converted to malate, then transported to sheath cells. |
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Term
| What happens when the malate is in the sheath cells? |
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Definition
| Decarboxylated to produce pyruvate and CO2. |
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Term
| What then happens to pyruvate and CO2 after they are produced? |
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Definition
| Carbon fixation occurs by rubsico and the calvin cycle (all within the bundle-sheath cells) |
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Term
| In c4 pathway, to produce a single glucose - how many ATP are required? |
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Definition
| An additional 12 versus the calvin cycle alone. |
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Term
| When is c4 respiration advantegous? |
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Definition
| In hot dry weather when photorespiration would remove more than half of the carbon fixed by the usual C3 pathway. |
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Term
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Definition
| Many succulent plants such as cacti, pineapples etc. Stomata open at night and close during the day. Fix CO2 using PEP carboxylase during the night and store in vacuole. Released stored CO2 internally during the day which leads to a high internal co2 concentration. This helps minimize water loss during the day. |
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