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Light-dependent reactions of photosynthesis at the thylakoid membrane. Light-dependent reactions are certain photochemical reactions involved in photosynthesis, the main process by which plants acquire energy. There are two light dependent reactions: the first occurs at photosystem II (PSII) and the second occurs at photosystem I (PSI).
Using longer wavelengths means less light energy is needed for the same number of photons and therefore for the same amount of photosynthesis. For actual sunlight, where only 45% of the light is in the photosynthetically active wavelength range, the theoretical maximum efficiency of solar energy conversion is approximately 11%.
The Gibbs free energy is the energy available ("free") to do work. Any reaction that decreases the overall Gibbs free energy of a system will proceed spontaneously (given that the system is isobaric and also at constant temperature), although the reaction may proceed slowly if it is kinetically inhibited.
The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle [1] of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into glucose. The Calvin cycle is present in all photosynthetic eukaryotes and also many ...
The energy efficiency of a process involving chemical change may be expressed relative to these theoretical minima or maxima.The difference between the change of enthalpy and the change of Gibbs energy of a chemical transformation at a particular temperature indicates the heat input required or the heat removal (cooling) required to maintain ...
Photoexcitation is the first step in a photochemical process where the reactant is elevated to a state of higher energy, an excited state.The first law of photochemistry, known as the Grotthuss–Draper law (for chemists Theodor Grotthuss and John W. Draper), states that light must be absorbed by a chemical substance in order for a photochemical reaction to take place.
In the Arrhenius model of reaction rates, activation energy is the minimum amount of energy that must be available to reactants for a chemical reaction to occur. [1] The activation energy ( E a ) of a reaction is measured in kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol). [ 2 ]
It is the antithesis of a photochemical reaction, in which light is used to drive an endothermic chemical reaction. Here, light is generated from a chemically exothermic reaction. The chemiluminescence might be also induced by an electrochemical stimulus, in this case is called electrochemiluminescence .