Where does the electron transport chain get the high-energy electrons that are passed down the chain?
960463
From Nadh & Fadh2 they are like 'taxi's' that pick up 'h' and carry them to electron transport drop it off and just keep repeating the cycle.
277111
From respiration: Here, glucose molecules in the cell are broken down; the molecules have strong bond between them and so when they are broken, energy is provided(by mitochondria) and when new molecules are formed, energy is released, which the cell uses for various processes.\n\nFrom protein synthesis: It occurs on the ribosomes in the cytoplasm, and aminoacids are combined to form proteins and this releases energy.\n\nFrom ATP(adenosine tri-phosphate): The ATP molecule is a packet of energy which stores the energy released during any process going on in the cell and then releases the energy as and when required by the cell.
892306
There are two types of electron flow in the light reactions (cyclic and noncyclic). Noncyclic is basically a linear flow as the name appears. Both photosystem 1 and 2 are used. In noncyclic electron flow O2 is released and both ATP and NADPH2 are produced. In cyclic however only photosystem 1 is involved. There is no NADPH2 produced and no O2 is released, only ATP is produced. Photosystem 2 proceeds photosystem 1. Hope that helps.
975413
Passive Transport does not require chemical energy to allow molecules across the membrane.  \n\nOne method of passive transport is simple diffusion.  Diffusion is the movement of molecules across a membrane from areas of high concentration to low concentration or along the concentration gradient.  These molecules can pass readily directly through the membrane.\n\nAnother method is facilitated diffusion.  This method is dependant on structures called transport proteins.  These proteins are simply pore like structures that span the width of the membrane.  The two types are pores and gated channels.  Pores always remain open, but gated channels can open and close in response to stimuli.  Also, these pores can only transport molecules down the concentration gradient.  Some transport proteins are also substrate specific, meaning that they can only transport a specific type of molecule.
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The electrons ae transfered by nadph and energy is made by water through atp pump
406711
The Hydrogen atom is a donor/acceptor for the electron, it's kinda like a battery, or a hydroelectric energy plant. Imagine the electron is water it wants to get somewhere, and it turns a wheel (ATP Snythase) to create ATP to get there. That is a "big picture" the details you'll have to look up.
763006
correct. At the anode, electrons flow out of the system.
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So, I don't know if that last word was supposed to be photoelectrons or photons.  So, I'll do both.\n\nIf there is an energy gap, and the energy of the photon is sufficient to promote an electron from one of the energy states in the fermi sea to an allowed energy state above the gap, the electron can be promoted to a state above the energy gap, and a hole will be produced in the state it came from.  Because there are lots of vacant energy states above the energy gap, the electron is in the conduction band, and can move around lots...  That's how you get photoelectrons.\n\nNow, photons would be produced when those photoelectrons recombine with holes.  The photoelectron has some finite lifetime, after which it will recombine with a hole (probably not the same one).  This will result in the electon losing energy in the form of a photon.
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. Reading the Z-scheme\n\nWhenever molecules gain or lose electrons energy is involved. The Z-scheme is an energy diagram for electron transfer in the "light reactions" of plant photosynthesis. It applies equally well to photosynthesis by algae and cyanobacteria. The vertical energy scale shows each molecule’s ability to transfer an electron to (i.e., to reduce) the next one from left to right. The ones at the top transfer electrons easily to the ones below them, as it is a "downhill" reaction, energy-wise. However, for electron transfer from those at the bottom to those above them it is an "uphill" reaction and requires input of outside energy. The Z scheme shows the pathway of electron transfer from water to NADP+. Using this pathway, plants transform light energy into "electrical" energy (electron flow) and hence into chemical energy as reduced NADPH and ATP. Later in the "dark reactions" of photosynthesis, that chemical energy is further transformed into the chemical bonds in sugar molecules. In the complete process, carbon dioxide is joined into the sugar molecules and oxygen is released. Although it is not a structural diagram, the Z-scheme does give the sequence of electron flow (oxidation and reduction) with an energy perspective. The source of electrons is water (H2O). The large vertical red arrows represent excitation of reaction center chlorophyll molecules (by light energy) and the black arrows represent electron flow, which is downhill energy-wise. This particular version of the "Z-scheme" was developed for the novel, THE MUSIC OF SUNLIGHT by Sunlight Books in collaboration with the authors of this article.\n\nMn is the manganese center, a complex containing 4 manganese atoms, which splits two water molecules at a time into 4 protons (4H+), 4 electrons (4e-), and 2 oxygen atoms, as an oxygen molecule (O2). Tyr is a special tyrosine molecule, also sometimes referred to as Yz or simply as Z, which shuttles electrons to the "reaction center" of photosystem II (PSII). Chl P680 is the reaction center pair of chlorophyll a molecules of PSII. Excited Chl P680* has reached this state by absorbing a photon of light energy. Pheo is a pheophytin molecule, which is a chlorophyll with its central magnesium ion (Mg++) having been replaced by two hydrogens. It is the primary electron acceptor of PSII, whereas P680 is the primary electron donor. QA is a plastoquinone molecule, which is tightly bound and immovable. It is known in some circles as the primary stable electron acceptor of PSII, and it accepts and transfers one electron at a time. QB is a loosely bound plastoquinone molecule, which accepts two electrons and then takes on two protons, before it detaches and becomes mobile and called PQ. PQ is the detached plastoquinone molecule, which is mobile within the hydrophobic core of the thylakoid membrane. FeS is the Rieske iron-sulfur protein. Cyt f is cytochrome f. Cyt b6L and Cyt b6H are two cytochrome b6 molecules (of lower and higher energy). PC is plastocyanin, a highly mobile copper protein. Chl P700 and Excited Chl P700* are respectively the ground energy state and the excited energy state of the chlorophyll molecule of the "reaction center" of photosystem I. AO is a special chlorophyll a molecule that is the primary electron acceptor of PSI, whereas P700 is the primary electron donor of PSI. A1 is a phylloquinone (vitamin K) molecule. FX, FA, and FB are three separate immobile iron-sulfur protein centers. FD is ferredoxin, a somewhat mobile iron-sulfur protein. FNR is the enzyme ferredoxin-NADP oxidoreductase, which contains the active group, called FAD (flavin adenine dinucleotide). NADP+ is the oxidized form of nicotinamide adenine dinucleotide phosphate. NADPH is its reduced form.
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Bohr's theory states that each level that the electron of hydrogen can be promoted to from the ground state are of specific energy (ie the are quantized). When an electron moves between these levels, it either absorbs or emits energy that corresponds to the energy level that the electron is moving to. The spectral lines you are talking about are the emitted radiation caused by electrons that are moving back to the ground state. They can be used to work out how much energy the levels have.
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Electrons.\nPhotons.\nHeat.
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the electron transport chain occurs in the inner membrane.  the krebbs cycle occurs in the inner matrix and glycolysis occurs in the cytoplasm of the cell
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Its all about mobility.  \n\nHow does the energy (in the form of heat) get transported over the structure?  Lattice vibrations, right?\n\nThe bonds have to deform in order to vibrate, and the higher electronegativity, associated with a higher bond strength, is more resistant to the imposed deformations, and therefore to transporting the heat.\n\nExcept for radiant transport (and thats a factor of T^4) the best conductive insulator or convective insulator is... a vacuum.  No mass means no bucket in which to ship the energy.
821483
Chloroplasts contain structures called thylakoids.\n\nThe thylakoid membrane contains the two photosystems utilized by photosynthesis. Most simply, when light strikes the reaction centers of the photosystems, electrons are released into an electron transport chain. As electrons move through the chain,  protons are pumped from the stroma of the chloroplast to the lumen (inside) of the thylakoid. Since the thylakoid membrane is impermeable to protons, a gradient is eventually built up within the thylakoid. This gradient powers ATP synthesis.
454802
it's basically from the movement of electron transfer from one of the metal to the other. to know the flow of electrons from which metal to which, u need to know their standard reduction potentials
427554
light hits photosystem II in thylakoid membrane--> excites the electrons--> electrons move to carrier proteins-->electrons make it to photosystem I. but b/c electrons moved from photosysytem II to photosystem I there's an electron hole in photosystem II which is filled up by oxidizing water in the thylokoid space.\n\nhope it helps :) there's more than that but since u only asked photosystem II, i wont confuse u by giving other details.
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Oh Biology, how do I miss thee!!!!!  Ah that was some good times.  Cytochrome c oxidase is part of the respiration cycle and it accepts electrons.  That about all I can remember but thanks for the points and a trip down memory lane.