These pigments transfer the energy of their excited electrons to a special Photosystem II chlorophyll molecule, P680, that absorbs light best in the red region at 680 nanometers. The electrons from water flow to Photosystem II, replacing the electrons lost by P680..
Correspondingly, what is the role of p680 in photosynthesis?
P680. The reaction center chlorophyll (or the primary electron donor) of photosystem II that is most reactive and best in absorbing light at wavelength of 680 nm. P680 is a group of pigments that are excitonically coupled or that act as if the pigments are a single molecule when they absorb a photon.
Secondly, why is p680 the strongest oxidizing agent? The molecule is rapidly oxidized transferring its electron to the primary acceptor. Note: P680+ is the strongest biological oxidizing agent because it splits water into Hydrogen and Oxygen thus by oxidizing water P680 receives two electrons.
why is p680 necessary?
It is needed to capture enough energy to do the biosynthetic reactions of the dark reaction. Its reaction center is a molecule called P680 which absorbs light maximally at 680 nm.
What does p680 stand for?
P680, or Photosystem II primary donor, (where P stands for pigment) refers to either of the two special chlorophyll dimers (also named special pairs), PD1 or PD2.
Related Question Answers
How many ATP are formed in light reaction?
2 ATP
What is the role of oxygen in photosynthesis?
In photosynthesis, solar energy is harvested as chemical energy in a process that converts water and carbon dioxide to glucose. Oxygen is released as a byproduct. In cellular respiration, oxygen is used to break down glucose, releasing chemical energy and heat in the process.How many ATP are produced in photosynthesis?
It is a complex cycle of mostly phosphorylation (adding or removing phosphate) and oxidative (electron removal) chemical reactions whereby 6 molecules of CO2 are converted into one molecule of glucose. It requires the energy-releasing cleavage of high energy bonds of 18 ATPs and 12 NADPHs .What are the products of photosynthesis?
The reactants for photosynthesis are light energy, water, carbon dioxide and chlorophyll, while the products are glucose (sugar), oxygen and water.How is Nadph formed?
NADPH is formed on the stromal side of the thylakoid membrane, so it is released into the stroma. In a process called non-cyclic photophosphorylation (the "standard" form of the light-dependent reactions), electrons are removed from water and passed through PSII and PSI before ending up in NADPH.What is the function of photosystem 1?
Photosystem I (PSI, or plastocyanin-ferredoxin oxidoreductase) is the second photosystem in the photosynthetic light reactions of algae, plants, and some bacteria. Photosystem I is an integral membrane protein complex that uses light energy to produce the high energy carriers ATP and NADPH.What is the role of Plastoquinone?
Plastoquinone is one of the electron acceptors associated with Photosystem II in photosynthesis. It accepts two electrons and is reduced to Plastoquinol and as such acts as an electron and energy carrier in the electron transport process.What is Chemiosmosis in photosynthesis?
Chemiosmosis is the movement of ions across a semipermeable membrane, down their electrochemical gradient. An example of this would be the generation of adenosine triphosphate (ATP) by the movement of hydrogen ions (H+) across a membrane during cellular respiration or photosynthesis.What is the purpose of photosystem 2?
Photosystem II (PSII) is a specialized protein complex that uses light energy to drive the transfer of electrons from water to plastoquinone, resulting in the production of oxygen and the release of reduced plastoquinone into the photosynthetic membrane.What is the purpose of the Calvin cycle?
Converting Carbon Dioxide and Water Into Glucose In the most general sense, the primary function of the Calvin cycle is to make organic products that plants need using the products from the light reactions of photosynthesis (ATP and NADPH).How is p680 different from p700?
Photosystem I is located on the outer surface of the thylakoid membrane and is bind to the special reaction center known as P700, whereas PS II is located on the inner surface of the thylakoid membrane and the reaction center is known as P680.Is photosystem 1 cyclic or noncyclic?
Non-cyclic Electron Flow. Under certain conditions, the photoexcited electrons take an alternative path called cyclic electron flow, which uses photosystem I (P700) but not photosystem II (P680). This process produces no NADPH and no O2, but it does make ATP.How many ATP are produced in Noncyclic Photophosphorylation?
Because 6 turns of non cyclic photophosphorylation will produce 12 NADPH2 and 6 ATP molecules. And cyclic photophosphorylation will produce 12 ATP molecules.What color is p680?
red
Is ATP produced in photosystem 1 or 2?
Electrons are transferred sequentially between the two photosystems, with photosystem I acting to generate NADPH and photosystem II acting to generate ATP. The pathway of electron flow starts at photosystem II, which is homologous to the photosynthetic reaction center of R.What does the Calvin cycle produce?
The reactions of the Calvin cycle add carbon (from carbon dioxide in the atmosphere) to a simple five-carbon molecule called RuBP. These reactions use chemical energy from NADPH and ATP that were produced in the light reactions. The final product of the Calvin cycle is glucose.What are the two stages of photosynthesis?
The two stages of photosynthesis: Photosynthesis takes place in two stages: light-dependent reactions and the Calvin cycle (light-independent reactions). Light-dependent reactions, which take place in the thylakoid membrane, use light energy to make ATP and NADPH.What is the role of Rubisco in the Calvin cycle?
The enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase, most commonly known by the shorter name RuBisCO or just rubisco is used in the Calvin cycle to catalyze the first major step of carbon fixation. They estimate that every person on Earth is supported by about 44 kg of rubisco!Where does the Calvin cycle occur?
Unlike the light reactions, which take place in the thylakoid membrane, the reactions of the Calvin cycle take place in the stroma (the inner space of chloroplasts). This illustration shows that ATP and NADPH produced in the light reactions are used in the Calvin cycle to make sugar. 
