query: where does the light independent phase of photosynthesis occur

pos: Light-independent reactions the stroma caused by its phosphorylation. Light-independent reactions The light-independent reactions, or dark reactions, of photosynthesis are chemical reactions that convert carbon dioxide and other compounds into glucose. These reactions occur in the stroma, the fluid-filled area of a chloroplast outside the thylakoid membranes. These reactions take the products (ATP and NADPH) of light-dependent reactions and perform further chemical processes on them. These reactions are closely coupled to the thylakoid electron transport chain as reducing power provided by NADPH produced in the photosystem I is actively needed. The process of photorespiration, also known as C2 cycle, is also coupled to

pos: Light-independent reactions Light-independent reactions The light-independent reactions, or dark reactions, of photosynthesis are chemical reactions that convert carbon dioxide and other compounds into glucose. These reactions occur in the stroma, the fluid-filled area of a chloroplast outside the thylakoid membranes. These reactions take the products (ATP and NADPH) of light-dependent reactions and perform further chemical processes on them. These reactions are closely coupled to the thylakoid electron transport chain as reducing power provided by NADPH produced in the photosystem I is actively needed. The process of photorespiration, also known as C2 cycle, is also coupled to the dark reactions, as it results

pos: Stroma (fluid) Stroma (fluid) Stroma, in botany, refers to the colorless fluid surrounding the grana within the chloroplast. Within the stroma are grana, stacks of thylakoids, the sub-organelles, the daughter cells, where photosynthesis is commenced before the chemical changes are completed in the stroma. Photosynthesis occurs in two stages. In the first stage, "light-dependent reactions" capture the energy of light and use it to make the energy-storage molecules ATP and NADPH. During the second stage, the "light-independent reactions" use these products to capture and reduce carbon dioxide. The series of biochemical redox reactions which take place in the stroma are collectively called

pos: Stroma (fluid) the Calvin cycle or "light-independent reactions". There are three phases: carbon fixation, reduction reactions, and ribulose 1,5-bisphosphate (RuBP) regeneration. The stroma is also the location of chloroplast DNA and chloroplast ribosomes, and thus also the location of molecular processes including chloroplast DNA replication, and transcription/translation of some chloroplast proteins. Stroma (fluid) Stroma, in botany, refers to the colorless fluid surrounding the grana within the chloroplast. Within the stroma are grana, stacks of thylakoids, the sub-organelles, the daughter cells, where photosynthesis is commenced before the chemical changes are completed in the stroma. Photosynthesis occurs in two stages. In the first stage,

neg: Artificial photosynthesis of this topic includes the design and assembly of devices for the direct production of solar fuels, photoelectrochemistry and its application in fuel cells, and the engineering of enzymes and photoautotrophic microorganisms for microbial biofuel and biohydrogen production from sunlight. The photosynthetic reaction can be divided into two half-reactions of oxidation and reduction, both of which are essential to producing fuel. In plant photosynthesis, water molecules are photo-oxidized to release oxygen and protons. The second phase of plant photosynthesis (also known as the Calvin-Benson cycle) is a light-independent reaction that converts carbon dioxide into glucose (fuel). Researchers of artificial photosynthesis

neg: Photosynthesis the "light-independent reactions" use these products to capture and reduce carbon dioxide. Most organisms that utilize oxygenic photosynthesis use visible light for the light-dependent reactions, although at least three use shortwave infrared or, more specifically, far-red radiation. Some organisms employ even more radical variants of photosynthesis. Some archaea use a simpler method that employs a pigment similar to those used for vision in animals. The bacteriorhodopsin changes its configuration in response to sunlight, acting as a proton pump. This produces a proton gradient more directly, which is then converted to chemical energy. The process does not involve carbon dioxide fixation

neg: Photosynthetic efficiency The Gibbs free energy for converting a mole of CO to glucose is 114 kcal, whereas eight moles of photons of wavelength 600 nm contains 381 kcal, giving a nominal efficiency of 30%. However, photosynthesis can occur with light up to wavelength 720 nm so long as there is also light at wavelengths below 680 nm to keep Photosystem II operating (see Chlorophyll). 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

neg: Golden rice Asian countries, making it an excellent crop for targeting vitamin deficiencies. Golden rice differs from its parental strain by the addition of three beta-carotene biosynthesis genes. The parental strain can naturally produce beta-carotene in its leaves, where it is involved in photosynthesis. However, the plant does not normally produce the pigment in the endosperm, where photosynthesis does not occur. Golden rice has met significant opposition from environmental and anti-globalization activists that claim that there are sustainable, long-lasting and more efficient ways to solve vitamin A deficiency that do not compromise food, nutrition and financial security, as they claim golden rice

neg: Magnesium in biology for the efficiency of photosynthesis, allowing phase transitions to occur. Mg is probably taken up into chloroplasts to the greatest extent during the light-induced development from proplastid to chloroplast or etioplast to chloroplast. At these times, the synthesis of chlorophyll and the biogenesis of the thylakoid membrane stacks absolutely require the divalent cation. Whether Mg is able to move into and out of chloroplasts after this initial developmental phase has been the subject of several conflicting reports. Deshaies "et al." (1984) found that Mg did move in and out of isolated chloroplasts from young pea plants, but Gupta and Berkowitz

neg: Primary production ice insulates it at lower temperatures. However, the availability of light, the source of energy for photosynthesis, and mineral nutrients, the building blocks for new growth, play crucial roles in regulating primary production in the ocean. Available Earth System Models suggest that ongoing ocean bio-geochemical changes could trigger reductions in ocean NPP between 3% and 10% of current values depending on the emissions scenario. The sunlit zone of the ocean is called the photic zone (or euphotic zone). This is a relatively thin layer (10–100 m) near the ocean's surface where there is sufficient light for photosynthesis to occur. For

neg: Limnology a byproduct of this reaction. Because photosynthesis is light-limited, both photosynthesis and respiration occur during the daylight hours, while only respiration occurs during dark hours or in dark portions of an ecosystem. The balance between dissolved oxygen production and consumption is calculated as the aquatic metabolism rate. Vertical changes in the concentrations of dissolved oxygen are affected by both wind mixing of surface waters and the balance between photosynthesis and respiration of organic matter. These vertical changes, known as profiles, are based on similar principles as thermal stratification and light penetration. As light availability decreases deeper in the water column,

neg: Beam splitter glass side (blue) have no phase shift. This is due to the Fresnel equations, according to which reflection causes a phase shift only when light passing through a material of low refractive index is reflected at a material of high refractive index. This is the case in the transition of air to reflector, but not from glass to reflector (given that the refractive index of the reflector is in between that of glass and that of air). This does not apply to partial reflection by conductive (metallic) coatings, where other phase shifts occur in all paths (reflected and transmitted). We

neg: Photosynthesis carbon dioxide concentrations rise, the rate at which sugars are made by the light-independent reactions increases until limited by other factors. RuBisCO, the enzyme that captures carbon dioxide in the light-independent reactions, has a binding affinity for both carbon dioxide and oxygen. When the concentration of carbon dioxide is high, RuBisCO will fix carbon dioxide. However, if the carbon dioxide concentration is low, RuBisCO will bind oxygen instead of carbon dioxide. This process, called photorespiration, uses energy, but does not produce sugars. RuBisCO oxygenase activity is disadvantageous to plants for several reasons: The salvaging pathway for the products of RuBisCO

neg: Refractive index for infrared optics. According to the theory of relativity, no information can travel faster than the speed of light in vacuum, but this does not mean that the refractive index cannot be lower than 1. The refractive index measures the phase velocity of light, which does not carry information. The phase velocity is the speed at which the crests of the wave move and can be faster than the speed of light in vacuum, and thereby give a refractive index below 1. This can occur close to resonance frequencies, for absorbing media, in plasmas, and for X-rays. In the X-ray

neg: Pseudo-nitzschia commercial fishing are important to ensure the health of marine animals and their predators. Photosynthesis is essential for the production of domoic acid. Periods of darkness or chemical inhibition of photosynthesis has been shown to inhibit toxin production. Additionally, DA production peaks in the stationary phase of the growth cycle when cell division is slowed or absent. Production is minimal or nonexistent during the exponential phase, and ceases completely during the death phase of the growth cycle. Many factors have been linked to promotion of DA production, including sufficient light, elevated or decreased pH, and nutrition limitations. In one species,

neg: Ocean different vertical zones defined by physical and biological conditions. The pelagic zone includes all open ocean regions, and can be divided into further regions categorized by depth and light abundance. The photic zone includes the oceans from the surface to a depth of 200 m; it is the region where photosynthesis can occur and is, therefore, the most biodiverse. Because plants require photosynthesis, life found deeper than the photic zone must either rely on material sinking from above (see marine snow) or find another energy source. Hydrothermal vents are the primary source of energy in what is known as the

neg: Carbon dioxide in Earth's atmosphere able to synthesize food directly from and water using energy from light. However, not all organisms that use light as a source of energy carry out photosynthesis, since "photoheterotrophs" use organic compounds, rather than , as a source of carbon. In plants, algae and cyanobacteria, photosynthesis releases oxygen. This is called "oxygenic photosynthesis". Although there are some differences between oxygenic photosynthesis in plants, algae, and cyanobacteria, the overall process is quite similar in these organisms. However, there are some types of bacteria that carry out anoxygenic photosynthesis, which consumes but does not release oxygen. Carbon dioxide is converted into sugars

neg: High-nutrient, low-chlorophyll regions production is the process by which autotrophs use light to convert carbon from aqueous carbon dioxide to sugar for cellular growth. Light catalyzes the photosynthetic process and nutrients are incorporated into organic material. For photosynthesis to occur, macronutrients such as nitrate and phosphate must be available in sufficient ratios and bioavailable forms for biological utilization. The molecular ratio of 106(Carbon):16(Nitrogen):1(Phosphorus) was discovered by Redfield, Ketcham, and Richards (RKR) and is known as the Redfield Ratio. Photosynthesis (forward) and respiration (reverse) is represented by the equation: Photosynthesis can be limited by deficiencies of certain macronutrients. However, in the North Pacific, the

neg: Dole effect in preference to O, increasing the relative amount of O in the atmosphere. The inequality is balanced by photosynthesis. Photosynthesis emits oxygen with the same isotopic composition (i.e. the ratio between O and O) as the water (HO) used in the reaction, which is independent of the atmospheric ratio. Thus when atmospheric O levels are high enough, photosynthesis will act as a reducing factor. However, as a complicating factor, the degree of fractionation (i.e. change in isotope ratio) occurring due to photosynthesis is not "entirely" dependent on the water drawn up by the plant, as fractionation can occur as a

neg: Phase transition of the external conditions at which the transformation occurs is termed the phase transition. Phase transitions commonly occur in nature and are used today in many technologies. Examples of phase transitions include: Phase transitions occur when the thermodynamic free energy of a system is non-analytic for some choice of thermodynamic variables (cf. phases). This condition generally stems from the interactions of a large number of particles in a system, and does not appear in systems that are too small. It is important to note that phase transitions can occur and are defined for non-thermodynamic systems, where temperature is not a

neg: Light curve (botany) ATP and NADPH than can be utilized by the light-independent reactions. Since photosynthesis is also limited by ambient carbon dioxide levels, light curves are often repeated at several different constant carbon dioxide concentrations. Light curve (botany) In botany, a light curve shows the photosynthetic response of leaf tissue or algal communities to varying light intensities. The shape of the curve illustrates the principle of limiting factors; in low light levels, the rate of photosynthesis is limited by the concentration of chlorophyll and the efficiency of the light-dependent reactions, but in higher light levels it is limited by the efficiency of

neg: Reactive oxygen species production in marine microalgae toxic than those in the stationary or late exponential phase. Many other algal species ("Heterosigma akashiwo", "Chattonella marina", and "Chattonella antiqua") have also been shown to produce the highest amounts of ROS during the exponential phase of growth. Oda "et al." suggest this is due to actively growing cells having higher photosynthesis and metabolic rates. Resting stage cells of "Chattonella antiqua" have been shown to generate less superoxide than their motile counterparts. Since superoxide is produced through the auto-oxidation of an electron acceptor in photosystem I during photosynthesis, one would expect a positive relationship between light levels and algal ROS

neg: Photosynthesis plants, light-dependent reactions occur in the thylakoid membranes of the chloroplasts where they drive the synthesis of ATP and NADPH. The light-dependent reactions are of two forms: cyclic and non-cyclic. In the non-cyclic reaction, the photons are captured in the light-harvesting antenna complexes of photosystem II by chlorophyll and other accessory pigments (see diagram at right). The absorption of a photon by the antenna complex frees an electron by a process called photoinduced charge separation. The antenna system is at the core of the chlorophyll molecule of the photosystem II reaction center. That freed electron is transferred to the primary

neg: Fractionation of carbon isotopes in oxygenic photosynthesis + 2 H + 3 ATP + OThe light-independent reactions undergo the Calvin-Benson cycle, in which the energy from NADPH and ATP is used to convert carbon dioxide and water into organic compounds via the enzyme RuBisCO. The overall general equation for the light-independent reactions is the following:3 CO + 9 ATP + 6 NADPH + 6 H → CHO-phosphate + 9 ADP + 8 P + 6 NADP + 3 HOThe 3-carbon products (CHO-phosphate) of the Calvin cycle are later converted to glucose or other carbohydrates such as starch, sucrose, and cellulose. The large fractionation of C in photosynthesis

neg: Photosynthesis and does not release oxygen, and seems to have evolved separately from the more common types of photosynthesis. In photosynthetic bacteria, the proteins that gather light for photosynthesis are embedded in cell membranes. In its simplest form, this involves the membrane surrounding the cell itself. However, the membrane may be tightly folded into cylindrical sheets called thylakoids, or bunched up into round vesicles called "intracytoplasmic membranes". These structures can fill most of the interior of a cell, giving the membrane a very large surface area and therefore increasing the amount of light that the bacteria can absorb. In plants and

neg: Phototroph live in aquatic environments, and will, using light, oxidize chemical substances such as hydrogen sulfide rather than water. In an ecological context, phototrophs are often the food source for neighboring heterotrophic life. In terrestrial environments, plants are the predominant variety, while aquatic environments include a range of phototrophic organisms such as algae (e.g., kelp), other protists (such as euglena), phytoplankton, and bacteria (such as cyanobacteria). The depth to which sunlight or artificial light can penetrate into water, so that photosynthesis may occur, is known as the photic zone. Cyanobacteria, which are prokaryotic organisms which carry out oxygenic photosynthesis, occupy many

neg: Fractionation of carbon isotopes in oxygenic photosynthesis defined in relation to the Vienna Pee Dee Belemnite (VPDB, C/C = 0.01118) as an established reference standard. This is called a "delta value" and can be calculated from the formula below: formula_1 The chemical pathway of oxygenic photosynthesis fixes carbon in two stages: the light-dependent reactions and the light-independent reactions. The light-dependent reactions capture light energy to transfer electrons from water and convert NADP, ADP, and inorganic phosphate into the energy-storage molecules NADPH and ATP. The overall equation for the light-dependent reactions is generally:2 HO + 2 NADP + 3 ADP + 3 P + light → 2 NADPH

neg: Etiolation cell to expand. Chloroplasts that have not been exposed to light are called etioplasts (see also plastids). De-etiolation, is a series of physiological and biochemical changes a plant shoot undergoes when emerging from the ground or in response to light after a period of insufficient light exposure. This process is known informally as greening. These changes that are triggered in the plants shoots or already formed leaves and stems occur in preparation for photosynthesis. Some of the changes that occur include: This process is regulated by the exposure of various photoreceptor pigments to light. Phytochrome A and phytochrome B both

neg: Carnivorous plant axis: as investment increases, so too does the photosynthesis of the trap, as the leaf receives a better supply of nitrogen and phosphorus. Eventually another factor (such as light intensity or carbon dioxide concentration) will become more limiting to photosynthesis than nitrogen or phosphorus supply. As a result, increasing the investment will not make the plant grow better. The net uptake of carbon dioxide, and therefore, the plant's potential for growth, must be positive for the plant to survive. There is a broad span of investment where this is the case, and there is also a non-zero optimum. Plants investing

neg: PI curve than those necessary for achievement of Pmax. Terms not included in the above equation are: Data sets showing interspecific differences and population dynamics. The hyperbolic response between photosynthesis and irradiance, depicted by the PI curve, is important for assessing phytoplankton population dynamics, which influence many aspects of the marine environment. PI curve The PI (photosynthesis-irradiance) curve is a graphical representation of the empirical relationship between solar irradiance and photosynthesis. A derivation of the Michaelis–Menten curve, it shows the generally positive correlation between light intensity and photosynthetic rate. Plotted along the "x"-axis is the independent variable, light intensity (irradiance), while the

neg: Photosynthesis this process is: This equation emphasizes that water is both a reactant in the light-dependent reaction and a product of the light-independent reaction, but canceling "n" water molecules from each side gives the net equation: Other processes substitute other compounds (such as arsenite) for water in the electron-supply role; for example some microbes use sunlight to oxidize arsenite to arsenate: The equation for this reaction is: Photosynthesis occurs in two stages. In the first stage, "light-dependent reactions" or "light reactions" capture the energy of light and use it to make the energy-storage molecules ATP and NADPH. During the second stage,

neg: Photosystem II Photosystem II Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants, algae, and cyanobacteria. Within the photosystem, enzymes capture photons of light to energize electrons that are then transferred through a variety of coenzymes and cofactors to reduce plastoquinone to plastoquinol. The energized electrons are replaced by oxidizing water to form hydrogen ions and molecular oxygen. By replenishing lost electrons with electrons from the splitting of water, photosystem II provides the electrons for all of photosynthesis to occur. The hydrogen ions (protons) generated

neg: Phase problem Phase problem In physics, the phase problem is the problem of loss of information concerning the phase that can occur when making a physical measurement. The name comes from the field of X-ray crystallography, where the phase problem has to be solved for the determination of a structure from diffraction data. The phase problem is also met in the fields of imaging and signal processing. Various approaches have been developed over the years that attempt to solve it. Light detectors, such as photographic plates or CCDs, measure only the intensity of the light that hits them. This measurement is incomplete

neg: Light-dependent reactions place only in the presence of light. This led later to the discovery of photosystems I and II. Light-dependent reactions In photosynthesis, the light-dependent reactions take place on the thylakoid membranes. The inside of the thylakoid membrane is called the lumen, and outside the thylakoid membrane is the stroma, where the light-independent reactions take place. The thylakoid membrane contains some integral membrane protein complexes that catalyze the light reactions. There are four major protein complexes in the thylakoid membrane: Photosystem II (PSII), Cytochrome b6f complex, Photosystem I (PSI), and ATP synthase. These four complexes work together to ultimately create the

neg: Light-dependent reactions Light-dependent reactions In photosynthesis, the light-dependent reactions take place on the thylakoid membranes. The inside of the thylakoid membrane is called the lumen, and outside the thylakoid membrane is the stroma, where the light-independent reactions take place. The thylakoid membrane contains some integral membrane protein complexes that catalyze the light reactions. There are four major protein complexes in the thylakoid membrane: Photosystem II (PSII), Cytochrome b6f complex, Photosystem I (PSI), and ATP synthase. These four complexes work together to ultimately create the products ATP and NADPH. The four photosystems absorb light energy through pigments—primarily the chlorophylls, which are responsible for

neg: African-American Vernacular English English but which speakers of light Black English may occasionally "dip into for humorous or emotive effect": Although AAVE does not necessarily have the simple past-tense marker of other English varieties (that is, the "-ed" of "work"ed""), it does have an optional tense system with at least four aspects of the past tense and two aspects of the future tense. Syntactically, "I bought it" is grammatical, but "done" (always unstressed, pronounced as /dən/) is used to emphasize the completed nature of the action. As phase auxiliary verbs, "been" and "done" must occur as the first auxiliary; when they occur as

neg: Phase diagram with ice will change abruptly as the container is heated past the melting point. The open spaces, where the free energy is analytic, correspond to single phase regions. Single phase regions are separated by lines of non-analytical behavior, where phase transitions occur, which are called phase boundaries. In the diagram on the right, the phase boundary between liquid and gas does not continue indefinitely. Instead, it terminates at a point on the phase diagram called the critical point. This reflects the fact that, at extremely high temperatures and pressures, the liquid and gaseous phases become indistinguishable, in what is known

neg: PI curve PI curve The PI (photosynthesis-irradiance) curve is a graphical representation of the empirical relationship between solar irradiance and photosynthesis. A derivation of the Michaelis–Menten curve, it shows the generally positive correlation between light intensity and photosynthetic rate. Plotted along the "x"-axis is the independent variable, light intensity (irradiance), while the "y"-axis is reserved for the dependent variable, photosynthetic rate. The PI curve can be applied to terrestrial and marine reactions but is most commonly used to explain ocean-dwelling phytoplankton’s photosynthetic response to changes in light intensity. Using this tool to approximate biological productivity is important because phytoplankton contribute ~50% of

neg: Light-independent reactions texts list a product of photosynthesis as , this is mainly a convenience to counter the equation of respiration, where six-carbon sugars are oxidized in mitochondria. The carbohydrate products of the Calvin cycle are three-carbon sugar phosphate molecules, or "triose phosphates", namely, glyceraldehyde-3-phosphate (G3P). In the first stage of the Calvin cycle, a molecule is incorporated into one of two three-carbon molecules (glyceraldehyde 3-phosphate or G3P), where it uses up two molecules of ATP and two molecules of NADPH, which had been produced in the light-dependent stage. The three steps involved are: The next stage in the Calvin cycle is

neg: Industrial fermentation cell protein, bakers yeast, lactobacillus, E. coli, and others. In the case of single-cell protein, algae is grown in large open ponds which allow photosynthesis to occur. If the biomass is to be used for inoculation of other fermentations, care must be taken to prevent mutations from occurring. Metabolites can be divided into two groups: those produced during the growth phase of the organism, called primary metabolites and those produced during the stationary phase, called secondary metabolites. Some examples of primary metabolites are ethanol, citric acid, glutamic acid, lysine, vitamins and polysaccharides. Some examples of secondary metabolites are penicillin, cyclosporin

neg: Epigeal germination to develop, so they are more frequent on nutrient-rich soils. The plants also need relatively much sunlight for photosynthesis to take place. Therefore they can be found more often in the field, at the border of forests, or as pioneer species. Plants that show epigeal germination grow relatively fast, especially in the first phase when the leaflets unfold. Because of this, they occur frequently in areas that experience regular flooding, for example at the river borders in the Amazon region. The fast germination enables the plant to develop before the next flooding takes place. After the faster first phase, the

neg: Photosynthesis cytosol they turn back into CO very slowly without the help of carbonic anhydrase. This causes the HCO ions to accumulate within the cell from where they diffuse into the carboxysomes. Pyrenoids in algae and hornworts also act to concentrate around rubisco. The overall process of photosynthesis takes place in four stages: Plants usually convert light into chemical energy with a photosynthetic efficiency of 3–6%. Absorbed light that is unconverted is dissipated primarily as heat, with a small fraction (1–2%) re-emitted as chlorophyll fluorescence at longer (redder) wavelengths. This fact allows measurement of the light reaction of photosynthesis by using

neg: Planetary habitability however. On a red dwarf planet, photosynthesis on the night side would be impossible, since it would never see the sun. On the day side, because the sun does not rise or set, areas in the shadows of mountains would remain so forever. Photosynthesis as we understand it would be complicated by the fact that a red dwarf produces most of its radiation in the infrared, and on the Earth the process depends on visible light. There are potential positives to this scenario. Numerous terrestrial ecosystems rely on chemosynthesis rather than photosynthesis, for instance, which would be possible in a

neg: Hill reaction which oxygen is released takes place within the chloroplast of plants and the Hill reaction demonstrated that the release of oxygen (O) is only a partial reaction which requires one step of photosynthesis. The Hill reaction implies that the light dependent reaction of photosynthesis is a result of a series of redox reactions and a suitable terminal electron acceptor is required for that reaction to occur. Plants have natural electron acceptors such as NADP, that play a major role in the oxidation of water. The Hill reaction also shows that the natural electron acceptors of the reaction can be substituted

neg: Photosynthetic state transition Photosynthetic state transition In photosynthesis, state transitions are rearrangements of the photosynthetic apparatus which occur on short time-scales (seconds to minutes). The effect is prominent in cyanobacteria, whereby the phycobilisome light-harvesting antenna complexes alter their preference for transfer of excitation energy between the two reaction centers, PS I and PS II. This shift helps to minimize photodamage caused by reactive oxygen species (ROS) under stressful conditions such as high light, but may also be used to offset imbalances between the rates of generating reductant and ATP. The phenomenon was first discovered in unicellular green algae, and may also occur in

neg: Instantaneous phase "t", where there is no change to integer "m", the derivative of "φ"("t") is This representation is similar to the wrapped phase representation in that it does not distinguish between multiples of 2π in the phase, but similar to the unwrapped phase representation since it is continuous. A vector-average phase can be obtained as the arg of the sum of the complex numbers without concern about wrap-around. Instantaneous phase Instantaneous phase and instantaneous frequency are important concepts in signal processing that occur in the context of the representation and analysis of time-varying functions. The instantaneous phase (or "local phase" or

neg: Glyceraldehyde 3-phosphate pathways. Furthermore, it is a participant in and a product of the pentose phosphate pathway. During plant photosynthesis, 2 equivalents of glycerate 3-phosphate (GP; also known as 3-phosphoglycerate) are produced by the first step of the light-independent reactions when ribulose 1,5-bisphosphate (RuBP) and carbon dioxide are catalysed by the rubisco enzyme. The GP is converted to D-glyceraldehyde 3-phosphate (G3P) using the energy in ATP and the reducing power of NADPH as part of the Calvin cycle. This returns ADP, phosphate ions Pi, and NADP+ to the light-dependent reactions of photosynthesis for their continued function. RuBP is regenerated for the Calvin

neg: Photosynthetically active radiation metrics such as luminous flux and illuminance is that these measures are based on human perception of brightness, which is strongly green biased and does not accurately describe the quantity of light usable for photosynthesis. The irradiance of PAR can be measured in energy units (W/m), which is relevant in energy-balance considerations for photosynthetic organisms. However, photosynthesis is a quantum process and the chemical reactions of photosynthesis are more dependent on the number of photons than the energy contained in the photons. Therefore, plant biologists often quantify PAR using the number of photons in the 400-700 nm range received by

neg: DCMU effect on photosystem I or other reactions in photosynthesis, such as light absorption or carbon fixation in the Calvin cycle. However, because it absorbs electrons oxidized from water in PS II, the electron "hole" of PS I cannot be satisfied, effectively shutting down "linear" photosynthesis by blocking the reduction of NADP to NADPH. At the same time, it was found that DCMU not only does not inhibit the cyclic photosynthetic pathway, but, under certain circumstances, actually stimulates it. Because of these effects, DCMU is often used to study energy flow in photosynthesis. DCMU DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is an algicide and herbicide

neg: Chlorobium chlorochromatii a free-living state in naturally occurring bacterial communities. "C. chlorochromatii" conducts anoxygenic photosynthesis which means it does not produce oxygen as a waste product like plants and cyanobacteria, this type of photosynthesis is exclusive to Bacteria. In their electron transport chain reduced forms of sulfur, e.g., HS. These reduced forms of sulfur are used in the electron transport chain cyclic Photosystem 1 as electron donors to reduce NADP+ to NADPH. It grows under strictly anaerobic conditions as a photolithoautotroph. They grow best at a pH of 7.0-7.3 at 25 C in continuous light and absorb light maximally at 748 and

neg: Herbert S. Gutowsky in membranes. He also collaborated with Govindjee and his photosynthesis research group in Biophysics during 1976—1986, using NMR, fluorescence, and pulsed light/oxygen to study the evolution of biomembranes and investigate the physico-chemical mechanisms of photosynthesis. After the early death of his friend Willis H. Flygare in 1981, Gutowsky established a second research career, extending Flygare's work with Fourier transform spectroscopy. Gutowsky's group examined the rotational spectra of weakly bound molecules in the gas phase, and was the first to use this method to study trimers, tetramers, and pentamers. He established the length of the silicon–carbon double bond and the rotational

neg: Ecosystem of the North Pacific Subtropical Gyre The low biomass results in clear water, allowing photosynthesis to occur to a substantial depth. The NPSG is classically described as a two-layered system. The upper, nutrient-limited layer accounts for most of the primary production, supported primarily by recycled nutrients. The lower layer has nutrients more readily available, but photosynthesis is light-limited. In open-ocean systems, biological production depends on intense nutrient recycling within the euphotic (sunlit) zone, with only a small fraction supported by the input of “new” nutrients. Previously there was a perception that the NPSG was a marine desert and that “new” nutrients were not commonly added to

neg: Mola alexandrini that "Mola alexandrini" may be a senior synonym of "Mola ramsayi" through both historically and newly published morphological data. The ocean sunfish are in the genus "Mola", currently composed of three species: "Mola mola", "Mola alexandrini", "Mola tecta". "Mola alexandrini", belonging to the family Molidae, was first discovered in the Oman Sea in Iran in August 2013 (Yasemi and Narari Bejgan, 2013). Also known as the southern ocean sunfish or southern sunfish, "Mola alexandrini" are commonly found in the epipelagic zone of the ocean which is the part of the ocean where enough light penetrates for photosynthesis to occur (Matsuura,

neg: Plant stress measurement lighted conditions to reach steady state photosynthesis before measurement. “Understanding of the organization of plant antennae, or plant light collection structures, and reaction centers, where the photosynthetic light reaction actually takes place, has changed over the years. It is now understood that a single antennae does not link only to a single reaction center, as was previously described in the puddle model. Current evidence indicates that reaction centers are connected with shared antennae in terrestrial plants.” As a result, the parameters used to provide reliable measurements have changed to represent the newer understanding of this relationship. The model that represents

neg: Aarhus Letbane recognised that, if the option of full electrification was to be exercised, a catenary-free system may be chosen for the harbour-side element of Phase 1. By late 2012, it had already been decided that Germany's BOStrab light rail regulations would be applied to the tentative network, while Lloyd's Register was appointed to serve as the independent safety assessor. By mid-2012, construction activity was scheduled to begin during June 2013, while the light rail network's opening was planned to occur during August 2016. On 8 May 2012, the Danish Parliament gave its approval for the construction of the Aarhus light rail

neg: Alpine plant plants, tissue desiccation is rare at high altitudes. If it does occur, it normally happens to plants growing on exposed sites, where wind stress is increased. Alpine plants avoid water loss by deep rooting and increased stomatal control. Plants at low elevation normally reach maximum stomatal opening in the morning while alpine plants reach maximum opening mid-day, when temperature is greatest. Alpine succulent plants often utilize CAM photosynthesis to avoid water loss. Because ultraviolet radiation tends to increase with elevation, it is often assumed to be a stress factor among alpine plants. In the past, there have been many attempts

neg: Reflection phase change Reflection phase change A phase change sometimes occurs when a wave is reflected. Such reflections occur for many types of wave, including light waves, sound waves, and waves on strings. Light waves change phase by 180° when they reflect from the surface of a medium with higher refractive index than that of the medium in which they are travelling. A light wave travelling in air that is reflected by a glass barrier will undergo a 180° phase change, while light travelling in glass "will not" undergo a phase change if it is reflected by a boundary with air. For this

neg: Oceanic zone no light penetrates. This is also called the midnight zone and the deep ocean. Due to the complete lack of sunlight, photosynthesis cannot occur and the only light source is bioluminescence. Water pressure is very intense and the temperatures are near freezing (range ). Oceanographers have divided the ocean into zones based on how far light reaches. All of the light zones can be found in the oceanic zone. The epipelagic zone is the one closest to the surface and is the best lit. It extends to 200 meters and contains both phytoplankton and zooplankton that can support larger organisms

neg: Understory tree species, such as dogwood and holly, rarely grow tall and generally are understory trees. The canopy of a rainforest is typically about 10m (33ft) thick, and intercepts around 95% of the sunlight. The understory receive less intense light than plants in the canopy and such light as does penetrate is impoverished in wavelengths of light that are most effective for photosynthesis. Understory plants therefore must be shade tolerant—they must be able to photosynthesize adequately using such light as does reach their leaves. They often are able to use wavelengths that canopy plants cannot. In temperate deciduous forests towards the

neg: Phase (waves) phase difference, and the oscillators are said to be out of phase with each other. The amount by which such oscillators are out of phase with each other can be expressed in degrees from 0° to 360°, or in radians from 0 to 2π. If the phase difference is 180 degrees (π radians), then the two oscillators are said to be in antiphase. If two interacting waves meet at a point where they are in antiphase, then destructive interference will occur. It is common for waves of electromagnetic (light, RF), acoustic (sound) or other energy to become superposed in their

neg: Urban resilience much larger coverage area. This both absorbs solar energy for photosynthesis (improving air quality and mitigating global warming), reducing the amount of energy being trapped and held within artificial surfaces, but also casts much-needed shade on the city and its inhabitants. Shade itself does not lower the ambient air temperature, but it greatly reduces the perceived temperature and comfort of those seeking its refuge. A popular method of reducing UHI is simply increasing the albedo (light reflectiveness) of urban surfaces that cannot be ‘greened’. This is done by using reflective paints or materials where appropriate, or white and light-coloured options

neg: Evolution of photosynthesis is evidence that the onset of C from is a biased signal, which only holds true for North America, from where most samples originate; emerging evidence suggests that grasslands evolved to a dominant state at least 15Ma earlier in South America. Evolution of photosynthesis The evolution of photosynthesis refers to the origin and subsequent evolution of photosynthesis, the process by which light energy synthesizes sugars from carbon dioxide, releasing oxygen as a waste product. The process of photosynthesis was discovered by Jan Ingenhousz, a Dutch-born British physician and scientist, first publishing about it in 1779. The first photosynthetic organisms probably

neg: Oscillatoria Oscillatoria Oscillatoria is a genus of filamentous cyanobacterium which is named after the oscillation in its movement. Filaments in the colonies can slide back and forth against each other until the whole mass is reoriented to its light source. It is commonly found in watering-troughs waters, and is mainly blue-green or brown-green. "Oscillatoria" is an organism that reproduces by fragmentation. "Oscillatoria" forms long filaments of cells which can break into fragments called hormogonia. The hormogonia can grow into a new, longer filament. Breaks in the filament usually occur where dead cells (necridia) are present. "Oscillatoria" uses photosynthesis to survive and

neg: Artificial photosynthesis particular how much of the incident light can be used in a system in practice. This is comparable with photosynthetic efficiency, where light-to-chemical-energy conversion is measured. Photosynthetic organisms are able to collect about 50% of incident solar radiation, however the theoretical limit of photosynthetic efficiency is 4.6 and 6.0% for C3 and C4 plants respectively. In reality, the efficiency of photosynthesis is much lower and is usually below 1%, with some exceptions such as sugarcane in tropical climate. In contrast, the highest reported efficiency for artificial photosynthesis lab prototypes is 22.4%. However, plants are efficient in using CO at atmospheric

neg: Photosynthetic efficiency Photosynthetic efficiency The photosynthetic efficiency is the fraction of light energy converted into chemical energy during photosynthesis in plants and algae. Photosynthesis can be described by the simplified chemical reaction where CHO is glucose (which is subsequently transformed into other sugars, cellulose, lignin, and so forth). The value of the photosynthetic efficiency is dependent on how light energy is defined – it depends on whether we count only the light that is absorbed, and on what kind of light is used (see Photosynthetically active radiation). It takes eight (or perhaps 10 or more) photons to utilize one molecule of CO.

neg: Chloroplast transformed into chemical energy, to subsequently produce food in the form of sugars. Water (HO) and carbon dioxide (CO) are used in photosynthesis, and sugar and oxygen (O) is made, using light energy. Photosynthesis is divided into two stages—the light reactions, where water is split to produce oxygen, and the dark reactions, or Calvin cycle, which builds sugar molecules from carbon dioxide. The two phases are linked by the energy carriers adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADP). The light reactions take place on the thylakoid membranes. They take light energy and store it in NADPH, a form

neg: Mode-locking a fixed phase between it and the other modes, the laser output behaves quite differently. Instead of a random or constant output intensity, the modes of the laser will periodically all constructively interfere with one another, producing an intense burst or pulse of light. Such a laser is said to be 'mode-locked' or 'phase-locked'. These pulses occur separated in time by , where "τ" is the time taken for the light to make exactly one round trip of the laser cavity. This time corresponds to a frequency exactly equal to the mode spacing of the laser, . The duration of

neg: Photoacoustic effect induced electron transfer process, causes a micro electrostriction effect with a change in the molecular volume. This, in turn, induces a pressure wave which propagates in the macroscopic medium. Another case for this mechanism is Bacteriorhodopsin proton pump. Here the light induced change in the molecular volume is caused by conformational changes that occur in this protein following light absorption. In applying the photoacoustic effect there exist various modes of measurement. Gaseous samples or condensed phase samples, where the pressure is measured in the surrounding gaseous phase, are usually probed with a microphone. The useful applicable time-scale in this case

neg: Emerson effect Emerson effect The Emerson effect is the increase in the rate of photosynthesis after chloroplasts are exposed to light of wavelength 680 nm (deep red spectrum) and more than 680 nm (far red spectrum). When simultaneously exposed to light of both wavelengths, the rate of photosynthesis is far higher than the sum of the red light and far red light photosynthesis rates. The effect was early evidence that two photosystems, processing different wavelengths, cooperate in photosynthesis. Robert Emerson described the eponymous effect in 1957. In his paper he observed that: When Emerson exposed green plants to differing wavelengths of light,

neg: Non-photochemical quenching Non-photochemical quenching Non-photochemical quenching (NPQ) is a mechanism employed by plants and algae to protect themselves from the adverse effects of high light intensity. It involves the quenching of singlet excited state chlorophylls (Chl) via enhanced internal conversion to the ground state (non-radiative decay), thus harmlessly dissipating excess excitation energy as heat through molecular vibrations. NPQ occurs in almost all photosynthetic eukaryotes (algae and plants), and helps to regulate and protect photosynthesis in environments where light energy absorption exceeds the capacity for light utilization in photosynthesis. When a molecule of chlorophyll absorbs light it is promoted from its ground state

neg: Chlorophyll a chemical energy but is not the only pigment that can be used for photosynthesis. All oxygenic photosynthetic organisms use chlorophyll "a", but differ in accessory pigments like chlorophylls "b". Chlorophyll "z" can also be found in very small quantities in the green sulfur bacteria, an anaerobic photoautotroph. These organisms use bacteriochlorophyll and some chlorophyll "a" but do not produce oxygen. Anoxygenic photosynthesis is the term applied to this process, unlike oxygenic photosynthesis where oxygen is produced during the light reactions of photosynthesis. The molecular structure of chlorophyll "a" consists of a chlorin ring, whose four nitrogen atoms surround a central

neg: Robin Hill (biochemist) Robin Hill (biochemist) Robert Hill FRS (2 April 1899 – 15 March 1991), known as Robin Hill, was a British plant biochemist who, in 1939, demonstrated the 'Hill reaction' of photosynthesis, proving that oxygen is evolved during the light requiring steps of photosynthesis. He also made significant contributions to the development of the Z-scheme of oxygenic photosynthesis. Hill was born in New Milverton, a suburb of Leamington Spa, Warwickshire. He was educated at Bedales School, where he became interested in biology and astronomy (he published a paper on sunspots in 1917), and Emmanuel College, Cambridge, where he read Natural Sciences.

neg: Methods of detecting exoplanets to detect large planets orbiting close to their parent star than other planets as these planets catch more light from their parent star. When a planet has a high albedo and is situated around a relatively luminous star, its light variations are easier to detect in visible light while darker planets or planets around low-temperature stars are more easily detectable with infrared light with this method. In the long run, this method may find the most planets that will be discovered by that mission because the reflected light variation with orbital phase is largely independent of orbital inclination and does

neg: Photosynthesis However, these experiments clearly show that temperature affects the rate of carbon assimilation, so there must be two sets of reactions in the full process of carbon assimilation. These are the light-dependent 'photochemical' temperature-independent stage, and the light-independent, temperature-dependent stage. Second, Blackman's experiments illustrate the concept of limiting factors. Another limiting factor is the wavelength of light. Cyanobacteria, which reside several meters underwater, cannot receive the correct wavelengths required to cause photoinduced charge separation in conventional photosynthetic pigments. To combat this problem, a series of proteins with different pigments surround the reaction center. This unit is called a phycobilisome. As

neg: Deep sea community that produce organic carbon. The stratum of the water column up till which sunlight penetrates is referred to as the photic zone. The photic zone can be subdivided into two different vertical regions. The uppermost portion of the photic zone, where there is adequate light to support photosynthesis by phytoplankton and plants, is referred to as the euphotic zone (also referred to as the "epipelagic zone", or "surface zone"). The lower portion of the photic zone, where the light intensity is insufficient for photosynthesis, is called the dysphotic zone (dysphotic means "poorly lit" in Greek). The dysphotic zone is also

neg: Macrocystis pyrifera mature regions to actively growing regions where the machinery of photosynthesis is not yet fully in place. Translocation also moves nutrients downward from light-exposed surface fronds to sporophylls (reproductive fronds) at the base of the kelp, where there is little light and thus little photosynthesis to produce food. "M. pyrifera" has been utilized for many years as a food source; it also contains many compounds such as iodine, potassium, other minerals vitamins and carbohydrates and thus has also been used as a dietary supplement. In the beginning of the 20th century California kelp beds were harvested as a source for

neg: Photonic metamaterial magnetic coupling component, or permeability. In other words, susceptibility to the magnetic component of radiated light can be considered negligible. Negative index metamaterials behave contrary to the conventional "right-handed" interaction of light found in conventional optical materials. Hence, these are dubbed left-handed materials or negative index materials (NIMs), among other nomenclatures. Only fabricated NIMs exhibit this capability. Photonic crystals, like many other known systems, can exhibit unusual propagation behavior such as reversal of phase and group velocities. However, negative refraction does not occur in these systems. Naturally occurring ferromagnetic and antiferromagnetic materials can achieve magnetic resonance, but with significant losses.

neg: Lorentz-violating electrodynamics arises. Vacuum dispersion of light without birefringence is another feature that is found, which does not arise in the minimal SME. Birefringence of light occurs when the solutions to the modified Lorentz-violating Maxwell equations give rise to polarization-dependent speeds. Light propagates as the combination of two orthogonal polarizations that propagate at slightly different phase velocities. A gradual change in the relative phase results as one of the polarizations outpaces the other. The total polarization (the sum of the two) evolves as the light propagates, in contrast to the Lorentz-invariant case where the polarization of light remains fixed when propagating in

neg: Photopigment Photopigment Photopigments are unstable pigments that undergo a chemical change when they absorb light. The term is generally applied to the non-protein chromophore moiety of photosensitive chromoproteins, such as the pigments involved in photosynthesis and photoreception. In medical terminology, "photopigment" commonly refers to the photoreceptor proteins of the retina. Photosynthetic pigments convert light into biochemical energy. Examples for photosynthetic pigments are chlorophyll, carotenoids and phycobilins. These pigments enter a high-energy state upon absorbing a photon which they can release in the form of chemical energy. This can occur via light-driven pumping of ions across a biological membrane (e.g. in the

neg: Fabry–Pérot interferometer electric-field and intensity reflectivities formula_8 and formula_9, respectively, at mirror formula_10 are If there are no other resonator losses, the photon-decay time formula_12 of the resonator is then given by With formula_14 quantifying the single-pass phase shift that light exhibits when propagating from one mirror to the other, the round-trip phase shift at frequency formula_15 accumulates to Resonances occur at frequencies at which light exhibits constructive interference after one round trip. Each resonator mode with its mode index formula_17, where formula_17 is an integer number in the interval [formula_19, …, −1, 0, 1, …, formula_20], is associated with a resonance

neg: Hamilton–Jacobi–Einstein equation the matter waves is a maximum. This can be expressed by the superposition principle; applied to many non-localized wavefunctions spread throughout the curved space to form a localized wavefunction: for some coefficients , and additionally the action (phase) for each must satisfy: for all "n", or equivalently, Regions where is maximal or minimal occur at points where there is a probability of finding the particle there, and where the action (phase) change is zero. So in the EHJE above, each wavefront of constant action is where the particle "could" be found. This equation still does not "unify" quantum mechanics and

neg: Compensation point Compensation point The (light) compensation point is the light intensity on the light curve where the rate of photosynthesis exactly matches the rate of cellular respiration. At this point, the uptake of CO through photosynthetic pathways is equal to the respiratory release of carbon dioxide, and the uptake of O by respiration is equal to the photosynthetic release of oxygen. In assimilation terms, at the compensation point, the net carbon dioxide assimilation is zero. Leaves release CO by photorespiration and cellular respiration, but CO is also converted into carbohydrate by photosynthesis. Assimilation is therefore the difference in the rate of

neg: Photosynthesis surface of the leaf is coated with a water-resistant waxy cuticle that protects the leaf from excessive evaporation of water and decreases the absorption of ultraviolet or blue light to reduce heating. The transparent epidermis layer allows light to pass through to the palisade mesophyll cells where most of the photosynthesis takes place. In the light-dependent reactions, one molecule of the pigment chlorophyll absorbs one photon and loses one electron. This electron is passed to a modified form of chlorophyll called pheophytin, which passes the electron to a quinone molecule, starting the flow of electrons down an electron transport chain

neg: Compensation point Products of photosynthesis are used up in respiration so that the organism is neither consuming nor building biomass. The net gaseous exchange is also zero at this point. For aquatic plants where the level of light at any given depth is roughly constant for most of the day, the compensation point is the depth at which light penetrating the water creates the same balanced effect. Respiration occurs by both plants and animals throughout the water column, resulting in the destruction, or usage, of organic matter, but photosynthesis can only take place via photosynthetic algae in the presence of light, nutrients

neg: C. B. van Niel Station of Stanford University. By studying purple sulfur bacteria and green sulfur bacteria he was the first scientist to demonstrate, in 1931, that photosynthesis is a light-dependent redox reaction in which hydrogen from an oxidizable compound reduces carbon dioxide to cellular materials. Expressed as: where A is the electron acceptor. His discovery predicted that HO is the hydrogen donor in green plant photosynthesis and is oxidized to O. The chemical summation of photosynthesis was a milestone in the understanding of the chemistry of photosynthesis. This was later experimentally verified by Robert Hill. In a nutshell, van Niel proved that plants

neg: Aerobic anoxygenic phototrophic bacteria Aerobic anoxygenic phototrophic bacteria Aerobic anoxygenic phototrophic bacteria (AAPBs) are alphaproteobacteria and gammaproteobacteriathat are obligate aerobes that capture energy from light by anoxygenic photosynthesis. Anoxygenic photosynthesis is the phototrophic process where light energy is captured and stored as ATP. The production of oxygen is non-existent and, therefore, water is not used as an electron donor. They are widely distributed marine plankton that may constitute over 10% of the open ocean microbial community. They can be particularly abundant in oligotrophic conditions where they were found to be 24% of the community. Aerobic anoxygenic phototrophic bacteria are photoheterotrophic (phototroph)microbes that exist in

neg: Photosynthesis Photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms' activities. This chemical energy is stored in carbohydrate molecules, such as sugars, which are synthesized from carbon dioxide and water – hence the name "photosynthesis", from the Greek φῶς, "phōs", "light", and σύνθεσις, "synthesis", "putting together". In most cases, oxygen is also released as a waste product. Most plants, most algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the

neg: Plastoquinone the cell membrane. One example of how it does this is by reacting with superoxides to form hydrogen peroxide and plastosemiquinone. The prefix "plasto-" means either plastid or chloroplast, alluding to its location within the cell. The role that plastoquinone plays in photosynthesis, more specifically in the light-dependent reactions of photosynthesis, is that of a mobile electron carrier through the membrane of the thylakoid. Plastoquinone is reduced when it accepts two electrons from photosystem II and two hydrogen cations (H) from the stroma of the chloroplast, thereby forming plastoquinol (PQH). It transfers the electrons further down the electron transport chain

neg: Photosynthesis that a complex of reactions consisting of an intermediate to cytochrome b (now a plastoquinone), another is from cytochrome f to a step in the carbohydrate-generating mechanisms. These are linked by plastoquinone, which does require energy to reduce cytochrome f for it is a sufficient reductant. Further experiments to prove that the oxygen developed during the photosynthesis of green plants came from water, were performed by Hill in 1937 and 1939. He showed that isolated chloroplasts give off oxygen in the presence of unnatural reducing agents like iron oxalate, ferricyanide or benzoquinone after exposure to light. The Hill reaction is

neg: Cell division the amount of cyclin increases, more and more cyclin dependent kinases attach to cyclin signaling the cell further into interphase. The peak of the cyclin attached to the cyclin dependent kinases this system pushes the cell out of interphase and into the M phase, where mitosis, meiosis, and cytokinesis occur. There are three transition checkpoints the cell goes through before entering the M phase. The most important being the G1-S transition checkpoint. If the cell does not pass this phase, then the cell will most likely not go through the rest of the cell division cycle. Prophase is the first

neg: Shot hole disease small (1/10-1/4”) reddish or purplish-brown spots with light green or yellow ring around them. As the disease progresses the damaged areas become slightly larger and then dry up and fall away, leaving BB-sized holes behind. As the fungus spreads, more leaf tissue is damaged until the leaf falls. Significant infections can reduce the amount of photosynthesis that can occur, weakening the plant, and decreasing fruit production. The infection on the fruits in turn begins as small purple spots that develop into gray to white lesions. Gummosis may occur (both on the fruits and the stems as well). These lesions leave

neg: Blueberry shock virus in progress to eliminate the disease and reduce loss of yield from it. The disease is important because it can cause a yield loss of 34-90% as documented by the Pacific Northwest. The magnitude of loss varies annually based on symptom severity and location. The main issue is leaf and foliage necrosis, which slows and neglects photosynthesis and therefore reduces blueberry (yield) quality. After one plant is infected and does survive, that plant becomes a reservoir for the virus for further inoculation to occur via vectors. The pollen-born spreading of the virus allows infection to occur on multiple blueberry patches

neg: Palisade cell Palisade cell Palisade cells are plant cells located in leaves, right below the epidermis and cuticle. They are vertically elongated, a different shape from the spongy mesophyll cells beneath them in the leaf. Their chloroplasts absorb a major portion of the light energy used by the leaf. Palisade cells occur in dicotyledonous plants, and also in the net-veined monocots, the Araceae and Dioscoreaceae. Palisade cells contain the largest number of chloroplasts per cell, which makes them the primary site of photosynthesis in the leaves of those plants that contain them, converting the energy in light to the chemical energy of

neg: Photoacoustic effect in the molecular organization, which results in molecular volume changes. Most prominent examples for these two kinds of mechanisms are in photosynthesis The first mechanism above is mostly conspicuous in a photosynthesizing plant leaf. There, the light induced oxygen evolution causes pressure changes in the air phase, resulting in a photoacoustic signal, which is comparable in magnitude to that caused by the photothermal mechanism. This mechanism was tentatively named "photobaric". The second mechanism shows up in photosynthetically active sub-cell complexes in suspension (e.g. photosynthetic reaction centers). There, the electric field which is formed in the reaction center, following the light

neg: Heliobacteria the International Journal of Systematic and Evolutionary Microbiology (IJSB/IJSEM). Heliobacteria The heliobacteria are phototrophic: they convert light energy into chemical energy by photosynthesis and they use a type I reaction center. The primary pigment involved is bacteriochlorophyll "g", which is unique to the group and has a unique absorption spectrum; this gives the heliobacteria their own environmental niche. Phototrophy takes place at the cell membrane, which does not form folds or compartments as it does in purple bacteria. Though heliobacteria are phototrophic, they can grow without light by fermentation of pyruvate. RNA trees place the heliobacteria among the Firmicutes, but

neg: Reflection phase change will be respectively positive or negative for inductors and capacitors. The phase shift will be exactly 90° when "X" = "Z". For the general case when the line is terminated with some arbitrary impedance, "Z", the reflected wave is generally less than the incident wave. The full expression for phase shift needs to be used, This expression assumes the characteristic impedance is purely resistive. Reflection phase change A phase change sometimes occurs when a wave is reflected. Such reflections occur for many types of wave, including light waves, sound waves, and waves on strings. Light waves change phase by 180°

neg: Heliobacteria Heliobacteria The heliobacteria are phototrophic: they convert light energy into chemical energy by photosynthesis and they use a type I reaction center. The primary pigment involved is bacteriochlorophyll "g", which is unique to the group and has a unique absorption spectrum; this gives the heliobacteria their own environmental niche. Phototrophy takes place at the cell membrane, which does not form folds or compartments as it does in purple bacteria. Though heliobacteria are phototrophic, they can grow without light by fermentation of pyruvate. RNA trees place the heliobacteria among the Firmicutes, but they do not stain Gram-positively. They have no outer

neg: Trace gas - natural or anthropogenic. Natural sources are caused by processes that occur in nature. In contrast, anthropogenic sources are caused by human activity. Some of the sources of a trace gas are biogenic, solid Earth (outgassing), the ocean, industrial activities, or in situ formation. A few examples of biogenic sources include photosynthesis, animal excrements, termites, rice paddies, and wetlands. Volcanoes are the main source for trace gases from solid earth. The global ocean is also a source of several trace gases, in particular sulfur-containing gases. In situ trace gas formation occurs through chemical reactions in the gas-phase. Anthropogenic sources are

neg: Thin-film interference This condition may change after considering possible phase shifts that occur upon reflection. Where incident light is monochromatic in nature, interference patterns appear as light and dark bands. Light bands correspond to regions at which constructive interference is occurring between the reflected waves and dark bands correspond to destructive interference regions. As the thickness of the film varies from one location to another, the interference may change from constructive to destructive. A good example of this phenomenon, termed "Newton's rings," demonstrates the interference pattern that results when light is reflected from a spherical surface adjacent to a flat surface. Concentric

neg: Photosynthesis oxygenase activity is more commonly known as photorespiration, since it is characterized by light-dependent oxygen consumption and the release of carbon dioxide. Photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms' activities. This chemical energy is stored in carbohydrate molecules, such as sugars, which are synthesized from carbon dioxide and water – hence the name "photosynthesis", from the Greek φῶς, "phōs", "light", and σύνθεσις, "synthesis", "putting together". In most cases, oxygen is also released as a waste product. Most plants, most algae,