What does the word Light dependent reactions mean?
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Photosynthesis consists of two stages: a series of light-dependent reactions that are temperature-independent and a series of temperature-dependent reactions that are light-independent. The rate of the first series, called the light reaction, can be increased by increasing light intensity (within certain limits) but not by increasing temperature. In the second series, called the dark reaction, the rate can be increased by increasing temperature (within certain limits) but not by increasing light intensity.\n\nThe first step in photosynthesis is the absorption of light by pigments. Chlorophyll is the most important of these because it is essential for the process. It captures light energy in the violet and red portions of the spectrum and transforms it into chemical energy through a series of reactions. Different forms of chlorophyll and other pigments known as carotenoids and phycobilins absorb slightly different wavelengths of light and pass the energy to a form of chlorophyll called chlorophyll A for the completion of the transformation process. These accessory pigments thus broaden the spectrum of light energy that can be fixed through photosynthesis.\n\nPhotosynthesis takes place within cells, in organelles called chloroplasts (in the leaves of plants) that contain the chlorophylls and other chemicals, especially enzymes, necessary for the various reactions. The chemicals involved are organized into units of the chloroplasts called thylakoids, and the pigments are embedded in the thylakoids in subunits called photosystems. Light is absorbed by the pigments, raising their electrons to higher energy levels. The energy is then transferred to a special form of chlorophyll A, called a reaction centre.\n\nTwo photosystems, numbered I and II, are recognized. Light energy is first trapped by photosystem II, and the energized electrons are boosted to an electron receptor. They are replaced in photosystem II by electrons from water molecules, and oxygen is released. The energized electrons are passed along an electron transport chain to photosystem I, and energy-rich adenosine triphosphate, or ATP, is generated in the process. Light energy absorbed by photosystem I is then passed to its reaction centre, and energized electrons are boosted to its electron acceptor. They are passed by means of another transport chain to energize the coenzyme (see Enzyme) nicotinamide adenine dinucleotide phosphate, or NADP, resulting in its reduction to NADPH2. The electrons lost by photosystem I are replaced by those passed along the electron transport chain from photosystem II. The light reaction ends with the energy yield stored in the ATP and NADPH2
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D is the correct answer, Light enables photosynthesis so a and c are wrong, and no reaction can increase exponentially as in B
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Yes, in a sense.  Einstein explained some phenomena in the photoelectric effect by postulating that light sometimes behaves as though it is composed of little particles with discrete energies.
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Light reactions take place on the thykaloid membranes of the chloroplast. Light reaction requires light and water, and produces ATP and Oxygen. Dark reactions take place in the stroma (fluid that fills the chloroplast). It uses the ATP produced in light reactions to make glucose.
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Many chemical reactions release energy in the form of heat, light, or sound. These are exothermic reactions. Exothermic reactions may occur spontaneously and result in higher randomness or entropy (ÄS > 0) of the system. They are denoted by a negative heat flow (heat is lost to the surroundings) and decrease in enthalpy (ÄH < 0). In the lab, exothermic reactions produce heat or may even be explosive. \nThere are other chemical reactions that must absorb energy in order to proceed. These are endothermic reactions. Endothermic reactions cannot occur spontaneously. Work must be done in order to get these reactions to occur. When endothermic reactions absorb energy, a temperature drop is measured during the reaction. Endothermic reactions are characterized by positive heat flow (into the reaction) and an increase in enthalpy (+ÄH). \n\nExamples of Endothermic and Exothermic Processes \n\nPhotosynthesis is an example of an endothermic chemical reaction. \nIn this process, plants use the energy from the sun to convert carbon dioxide and water into glucose and oxygen. This reaction requires 15MJ of energy (sunlight) for every kilogram of glucose that is produced: \nsunlight + 6CO2(g) + H2O(l) = C6H12O6(aq) + 6O2(g) \n\nAn example of an exothermic reaction is the mixture of sodium and chlorine to yield table salt. This reaction produces 411 kJ of energy for each mole of salt that is produced:\n\nNa(s) + 0.5Cl2(s) = NaCl(s) \n\nEndothermic reactions take in energy from their surroundings\n\nDissolution of salt is endothermic because it takes energy from its surroundings not much but some.\n\nAs far as all salt types that is hard to say and you would have to do an experiment to find that out.
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The sum of the chemical reactions that take place within each cell of a living organism and that provide energy for vital processes and for synthesizing new organic material.\n\nMy Adice to you: You seem to be doing a researh of some scientific sort. I recommend you take advantage of the internet which could help you in this regard. Try accessing an online Encyclopedia.\n\nGood Luck!
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It's not accurate to say they happen in the dark because you need the products from the light dependent reaction (ATP and NADPH) for the Calvin cycle to take place.  In the dark there are no photons to excite an electron from chlorophyll.  No proton gradient develops so no ATP is made and the electrons from chlorophyll don't get excited and passed to NAPD+ to make NADPH.  Carbon dioxide can't be fixed to form sugars without these compounds so the "dark" reaction actually do NEED light (albeit indirectly).
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when in a chemical reaction
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A solution could absorb energy from photons, but they are a measurement of light. Rather than being absorbed, for example, the solar radiation breaks down chemicals in the leaves of plants which allows the plants to form food. Rather than being absorbed, the energy causes a change, such as increased temperature and chemical reaction.
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it's reactive to light
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The short version: light hits a pigment molecule, like chlorophyll, and boosts an electron to a high-energy state.  That high-energy electron is then used to jam the phosphate group onto ADP or NADH.
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moving from a higher to a lower energy level releases energy, producing light, but;\nit only produces light in the visible light spectrum when it moves down to level n=2.  if it ends up at another energy level, the light released will be infared, ultraviolet, etc... depending on where it ends up.
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Process by which green plants and certain other organisms transform light into chemical energy. In green plants, light energy is captured by chlorophyll in the chloroplasts of the leaves and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds (simple and complex sugars) that are the basis of both plant and animal life. Photosynthesis consists of a number of photochemical and enzymatic reactions. It occurs in two stages. During the light-dependent stage (light reaction), chlorophyll absorbs light energy, which excites some electrons in the pigment molecules to higher energy levels; these leave the chlorophyll and pass along a series of molecules, generating formation of NADPH (an enzyme) and high-energy ATP molecules. Oxygen, released as a by-product, passes into the atmosphere through pores in the leaves. NADPH and ATP drive the second stage, the dark reaction (or Calvin cycle, discovered by Melvin Calvin), which does not require light. During this stage glucose is generated using atmospheric carbon dioxide. Photosynthesis is crucial for maintaining life on Earth; if it ceased, there would soon be little food or other organic matter on the planet, and most types of organisms would disappear.\n\n\n\n    6 CO2 + 12 H2O + light → C6H12O6 + 6 O2 + 6 H2O\n\n    Carbon Dioxide + Water + Light energy → Glucose + Oxygen + Water
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energy input: reaction requires energy to take place - endothermic\nenergy output: reaction gives off energy when it takes place - exothermic
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Photophosphorylation uses the energy from the sun to phosphorylate (add a phosphate group to) ATP. Oxidative phosphorylation involves the oxidation of organic molecules to produce the energy required to phosphorylate ATP.
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Most commonly observed optical effects (refraction, diffraction, reflection) are linear: if you double the amount of light at the source, the results observed also double. Similarly for decreases in the amount of light. There is a linear relationship between source intensity and observed intensity as the light passes through the optics (lens, mirrors, etc.).\n\nNon-linear optics don't behave that way at all. As the light intensity increases, the medium through which the light propagates (the optics) is stressed by the electrical or magnetic field (or both) of the light wave. This stress changes some physical property of the medium, such as its polarization or its refractive index, as a function of the light intensity. The result is a non-linear response of the material to the electromagnetic field of the light.\n\nThis can have some interesting consequences, such as the generation of harmonics of the original wavelength. It is this non-linear mechanism that allows a strong infrared, or near infrared, laser to be be frequency doubled or frequency tripled to produce coherent light at visible or ultraviolet wavelengths.
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I would have to guess that it involves the neutralization reaction of more than 2 substances.\n\nJust a guess