Leaves And Leaf Structure The Nature Of Light Chlorophyll And: Fill & Download for Free

SHORT VERSION: Photosynthesis (From the Greek φώτο- [photo-], "light," and σύνθεσις [synthesis], "putting together", "composition") is a process used by plants and other organisms to convert the light energy captured from the sun into chemical energy that can be used to fuel the organism's activities. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea.OK, Now the Very very long Version (Total in-depth explanation)What is Photosynthesis?Photosynthesisis the process by which plants, some bacteria, and some protistans use the energy from sunlight to produce sugar, which cellular respiration converts into ATP, the "fuel" used by all living things. The conversion of unusable sunlight energy into usable chemical energy, is associated with the actions of the green pigment chlorophyll. Most of the time, the photosynthetic process uses water and releases the oxygen that we absolutely must have to stay alive. Oh yes, we need the food as well!We can write the overall reaction of this process as:6H2O + 6CO2 ----------> C6H12O6+ 6O2Most of us don't speak chemicalese, so the above chemical equation translates as:six molecules of water plus six molecules of carbon dioxide produce one molecule of sugar plus six molecules of oxygenDiagram of a typical plant, showing the inputs and outputs of the photosynthetic process.Leaves and Leaf Structure:Plants are the only photosynthetic organisms to have leaves(and not all plants have leaves). A leaf may be viewed as a solar collector crammed full of photosynthetic cells.The raw materials of photosynthesis, water and carbon dioxide, enter the cells of the leaf, and the products of photosynthesis, sugar and oxygen, leave the leaf.Cross section of a leaf, showing the anatomical features important to the study of photosynthesis: stoma, guard cell, mesophyll cells, and vein.Water enters the root and is transported up to the leaves through specialized plant cells known as xylem(pronounces zigh-lem). Land plants must guard against drying out (desiccation) and so have evolved specialized structures known as stomata to allow gas to enter and leave the leaf. Carbon dioxide cannot pass through the protective waxy layer covering the leaf (cuticle), but it can enter the leaf through an opening (the stoma; plural = stomata; Greek for hole) flanked by two guard cells. Likewise, oxygen produced during photosynthesis can only pass out of the leaf through the opened stomata. Unfortunately for the plant, while these gases are moving between the inside and outside of the leaf, a great deal water is also lost. Cottonwood trees, for example, will lose 100 gallons of water per hour during hot desert days. Carbon dioxide enters single-celled and aquatic autotrophs through no specialized structures.Pea Leaf Stoma, Vicea sp. (SEM x3,520).The Nature of Light:White light is separated into the different colors (=wavelengths) of light by passing it through a prism. Wavelength is defined as the distance from peak to peak (or trough to trough). The energy of is inversely porportional to the wavelength: longer wavelengths have less energy than do shorter ones.Wavelength and other saspects of the wave nature of light.The order of colors is determined by the wavelength of light. Visible light is one small part of the electromagnetic spectrum. The longer the wavelength of visible light, the more red the color. Likewise the shorter wavelengths are towards the violet side of the spectrum. Wavelengths longer than red are referred to as infrared, while those shorter than violet are ultraviolet.The electromagnetic spectrum.Light behaves both as a wave and a particle. Wave properties of light include the bending of the wave path when passing from one material (medium) into another (i.e. the prism, rainbows, pencil in a glass-of-water, etc.). The particle properties are demonstrated by the photoelectric effect. Zinc exposed to ultraviolet light becomes positively charged because light energy forces electrons from the zinc. These electrons can create an electrical current. Sodium, potassium and selenium have critical wavelengths in the visible light range. The critical wavelength is the maximum wavelength of light (visible or invisible) that creates a photoelectric effect.Chlorophyll and Accessory Pigments:A pigment is any substance that absorbs light. The color of the pigment comes from the wavelengths of light reflected (in other words, those not absorbed). Chlorophyll, the green pigment common to all photosynthetic cells, absorbs all wavelengths of visible light except green, which it reflects to be detected by our eyes. Black pigments absorb all of the wavelengths that strike them. White pigments/lighter colors reflect all or almost all of the energy striking them. Pigments have their own characteristic absorption spectra, the absorption pattern of a given pigment.Absorption and transmission of different wavelengths of light by a hypothetical pigment.Chlorophyll is a complex molecule. Several modifications of chlorophyll occur among plants and other photosynthetic organisms. All photosynthetic organisms (plants, certain protistans, prochlorobacteria, and cyanobacteria) havechlorophyll a. Accessory pigments absorb energy that chlorophyll a does not absorb. Accessory pigments includechlorophyll b (also c, d, and e in algae and protistans), xanthophylls, and carotenoids(such as beta-carotene). Chlorophyll a absorbs its energy from the Violet-Blue and Reddish orange-Red wavelengths, and little from the intermediate (Green-Yellow-Orange) wavelengths.Molecular model of chlorophyll.Molecular model of carotene.Carotenoids and chlorophyll b absorb some of the energy in the green wavelength. Why not so much in the orange and yellow wavelengths? Both chlorophylls also absorb in the orange-red end of the spectrum (with longer wavelengths and lower energy). The origins of photosynthetic organisms in the sea may account for this. Shorter wavelengths (with more energy) do not penetrate much below 5 meters deep in sea water. The ability to absorb some energy from the longer (hence more penetrating) wavelengths might have been an advantage to early photosynthetic algae that were not able to be in the upper (photic) zone of the sea all the time.The molecular structure of chlorophylls.The action spectrum of photosynthesis is the relative effectiveness of different wavelengths of light at generating electrons. If a pigment absorbs light energy, one of three things will occur. Energy is dissipated as heat. The energy may be emitted immediately as a longer wavelength, a phenomenon known as fluorescence. Energy may trigger a chemical reaction, as in photosynthesis. Chlorophyll only triggers a chemical reaction when it is associated with proteins embedded in a membrane (as in a chloroplast) or the membrane infoldings found in photosynthetic prokaryotes such as cyanobacteria and prochlorobacteria.Absorption spectrum of several plant pigments (left) and action spectrum of elodea (right), a common aquarium plant used in lab experiments about photosynthesisThe structure of the chloroplast and photosynthetic membranes:The thylakoidis the structural unit of photosynthesis. Both photosynthetic prokaryotes and eukaryotes have these flattened sacs/vesicles containing photosynthetic chemicals. Only eukaryotes have chloroplasts with a surrounding membrane.Thylakoids are stacked like pancakes in stacks known collectively as grana. The areas between grana are referred to as stroma. While the mitochondrion has two membrane systems, the chloroplast has three, forming three compartments.Structure of a chloroplast.Stages of Photosynthesis:Photosynthesis is a two stage process. The first process is the Light Dependent Process (Light Reactions), requires the direct energy of light to make energy carrier molecules that are used in the second process. The Light Independent Process (or Dark Reactions) occurs when the products of the Light Reaction are used to form C-C covalent bonds of carbohydrates. The Dark Reactions can usually occur in the dark, if the energy carriers from the light process are present. Recent evidence suggests that a major enzyme of the Dark Reaction is indirectly stimulated by light, thus the term Dark Reaction is somewhat of a misnomer. The Light Reactions occur in the granaand the Dark Reactions take place in the stromaof the chloroplasts.Overview of the two steps in the photosynthesis process.Light Reactions:In the Light Dependent Processes (Light Reactions) light strikes chlorophyll a in such a way as to excite electrons to a higher energy state. In a series of reactions the energy is converted (along an electron transport process) into ATPand NADPH. Water is split in the process, releasing oxygen as a by-product of the reaction. The ATP and NADPH are used to make C-C bonds in the Light Independent Process (Dark Reactions).In the Light Independent Process, carbon dioxide from the atmosphere (or water for aquatic/marine organisms) is captured and modified by the addition of Hydrogen to form carbohydrates (general formula of carbohydrates is [CH2O]n). The incorporation of carbon dioxide into organic compounds is known as carbon fixation. The energy for this comes from the first phase of the photosynthetic process. Living systems cannot directly utilize light energy, but can, through a complicated series of reactions, convert it into C-C bond energy that can be released by glycolysis and other metabolic processes.Photosystemsare arrangements of chlorophyll and other pigments packed into thylakoids. Many Prokaryotes have only one photosystem, Photosystem II (so numbered because, while it was most likely the first to evolve, it was the second one discovered). Eukaryotes have Photosystem II plus Photosystem I. Photosystem I uses chlorophyll a, in the form referred to as P700. Photosystem II uses a form of chlorophyll a known as P680. Both "active" forms of chlorophyll a function in photosynthesis due to their association with proteins in the thylakoid membrane.Action of a photosystem.Photophosphorylationis the process of converting energy from a light-excited electron into the pyrophosphate bond of an ADP molecule. This occurs when the electrons from water are excited by the light in the presence of P680. The energy transfer is similar to the chemiosmotic electron transport occurring in the mitochondria. Light energy causes the removal of an electron from a molecule of P680 that is part of Photosystem II. The P680 requires an electron, which is taken from a water molecule, breaking the water into H+ ions and O-2 ions. These O-2 ions combine to form the diatomic O2 that is released. The electron is "boosted" to a higher energy state and attached to a primary electron acceptor, which begins a series of redox reactions, passing the electron through a series of electron carriers, eventually attaching it to a molecule in Photosystem I. Light acts on a molecule of P700 in Photosystem I, causing an electron to be "boosted" to a still higher potential. The electron is attached to a different primary electron acceptor (that is a different molecule from the one associated with Photosystem II). The electron is passed again through a series of redox reactions, eventually being attached to NADP+ and H+ to form NADPH, an energy carrier needed in the Light Independent Reaction. The electron from Photosystem II replaces the excited electron in the P700 molecule. There is thus a continuous flow of electrons from water to NADPH. This energy is used in Carbon Fixation. Cyclic Electron Flow occurs in some eukaryotes and primitive photosynthetic bacteria. No NADPH is produced, only ATP. This occurs when cells may require additional ATP, or when there is no NADP+ to reduce to NADPH. In Photosystem II, the pumping to H ions into the thylakoid and the conversion of ADP + P into ATP is driven by electron gradients established in the thylakoid membrane.Noncyclic photophosphorylation (top) and cyclic photophosphorylation (bottom). These processes are better known as the light reactionsThe above diagrams present the "old" view of photophosphorylation. We now know where the process occurs in the chloroplast, and can link that to chemiosmotic synthesis of ATP.Chemiosmosis as it operates in photophosphorylation within a chloroplast.Halobacteria, which grow in extremely salty water, are facultative aerobes, they can grow when oxygen is absent. Purple pigments, known as retinal (a pigment also found in the human eye) act similar to chlorophyll. The complex of retinal and membrane proteins is known as bacteriorhodopsin, which generates electrons which establish a proton gradient that powers an ADP-ATP pump, generating ATP from sunlight without chlorophyll. This supports the theory that chemiosmotic processes are universal in their ability to generate ATP.Dark Reaction:Carbon-Fixing Reactions are also known as the Dark Reactions (or Light Independent Reactions). Carbon dioxide enters single-celled and aquatic autotrophsthrough no specialized structures, diffusing into the cells. Land plants must guard against drying out (desiccation) and so have evolved specialized structures known as stomatato allow gas to enter and leave the leaf. The Calvin Cycle occurs in the stroma of chloroplasts (where would it occur in a prokaryote?). Carbon dioxide is captured by the chemical ribulose biphosphate (RuBP). RuBP is a 5-C chemical. Six molecules of carbon dioxide enter the Calvin Cycle, eventually producing one molecule of glucose. The reactions in this process were worked out by Melvin Calvin (shown below).Ernest Orlando Lawrence, Berkeley National Laboratory.One of the new areas, cultivated both in Donner and the Old Radiation Laboratory, was the study of organic compounds labeled with carbon-14. Melvin Calvin took charge of this work at the end of the war in order to provide raw materials for John Lawrence's researches and for his own study of photosynthesis. Using carbon-14, available in plenty from Hanford reactors, and the new techniques of ion exchange, paper chromatography, and radioautography, Calvin and his many associates mapped the complete path of carbon in photosynthesis. The accomplishment brought him the Nobel prize in chemistry in 1961. (The preceding information was excerpted from the text of the Fall 1981 issue of LBL Newsmagazine.) Citation Caption: LBL News, Vol.6, No.3, Fall 1981 Melvin Calvin shown with some of the apparatus he used to study the role of carbon in photosynthesis."The first steps in the Calvin cycle.The first stable product of the Calvin Cycle isphosphoglycerate (PGA), a 3-C chemical. The energy from ATP and NADPHenergy carriers generated by the photosystems is used to attach phosphates to (phosphorylate) the PGA. Eventually there are 12 molecules of glyceraldehyde phosphate (also known as phosphoglyceraldehyde or PGAL, a 3-C), two of which are removed from the cycle to make a glucose. The remaining PGAL molecules are converted by ATP energy to reform 6RuBPmolecules, and thus start the cycle again. Remember the complexity of life, each reaction in this process, as in Kreb's Cycle, is catalyzed by a different reaction-specific enzyme.C-4 Pathway:Some plants have developed a preliminary step to the Calvin Cycle (which is also referred to as a C-3 pathway), this preamble step is known as C-4. While most C-fixation begins with RuBP, C-4 begins with a new molecule, phosphoenolpyruvate (PEP), a 3-C chemical that is converted into oxaloacetic acid (OAA, a 4-C chemical) when carbon dioxide is combined with PEP. The OAA is converted to Malic Acid and then transported from themesophyllcell into the bundle-sheath cell, where OAA is broken down into PEP plus carbon dioxide. The carbon dioxide then enters the Calvin Cycle, with PEP returning to the mesophyll cell. The resulting sugars are now adjacent to the leaf veins and can readily be transported throughout the plant.C-4 photosynthsis involves the separation of carbon fixation and carbohydrate systhesis in space and time.The capture of carbon dioxide by PEP is mediated by the enzyme PEP carboxylase, which has a stronger affinity for carbon dioxide than does RuBP carboxylase When carbon dioxide levels decline below the threshold for RuBP carboxylase, RuBP is catalyzed with oxygen instead of carbon dioxide. The product of that reaction forms glycolic acid, a chemical that can be broken down by photorespiration, producing neither NADH nor ATP, in effect dismantling the Calvin Cycle. C-4 plants, which often grow close together, have had to adjust to decreased levels of carbon dioxide by artificially raising the carbon dioxide concentration in certain cells to prevent photorespiration. C-4 plants evolved in the tropics and are adapted to higher temperatures than are the C-3 plants found at higher latitudes. Common C-4 plants include crabgrass, corn, and sugar cane. Note that OAA and Malic Acid also have functions in other processes, thus the chemicals would have been present in all plants, leading scientists to hypothesize that C-4 mechanisms evolved several times independently in response to a similar environmental condition, a type of evolution known as convergent evolution.Photorespiration.We can see anatomical differences between C3 and C4 leaves.Leaf anatomy of a C3 (top) and C4 (bottom) plant.The Carbon Cycle:Plants may be viewed as carbon sinks, removing carbon dioxide from the atmosphere and oceans by fixing it into organic chemicals. Plants also produce some carbon dioxide by their respiration, but this is quickly used by photosynthesis. Plants also convert energy from light into chemical energy of C-C covalent bonds. Animals are carbon dioxide producers that derive their energy from carbohydrates and other chemicals produced by plants by the process of photosynthesis.The balance between the plant carbon dioxide removal and animal carbon dioxide generation is equalized also by the formation of carbonates in the oceans. This removes excess carbon dioxide from the air and water (both of which are in equilibrium with regard to carbon dioxide). Fossil fuels, such as petroleum and coal, as well as more recent fuels such as peat and wood generate carbon dioxide when burned. Fossil fuels are formed ultimately by organic processes, and represent also a tremendous carbon sink. Human activity has greatly increased the concentration of carbon dioxide in air. This increase has led to global warming, an increase in temperatures around the world, the Greenhouse Effect. The increase in carbon dioxide and other pollutants in the air has also led toacid rain, where water falls through polluted air and chemically combines with carbon dioxide, nitrous oxides, and sulfur oxides, producing rainfall with pH as low as 4. This results in fish kills and changes in soil pH which can alter the natural vegetation and uses of the land. The Global Warming problem can lead to melting of the ice caps in Greenland and Antarctica, raising sea-level as much as 120 meters. Changes in sea-level and temperature would affect climate changes, altering belts of grain production and rainfall patterns.Source: PHOTOSYNTHESIS

No, all plant cells don’t contain chloroplasts. The plant’s entire body isn’t green, just the green parts you can see with the naked eye - the leaves, of course, and sometimes stems. Besides the roots, which you mention, the trunk and branches of trees, bushes, and some small plants aren’t green; nor are the flowering parts, usually. Then, when you go down to the microscopic level, you see structures within the leaves that contain no chloroplasts.Mainly the chlorophyll-containing chloroplasts are located in the leaves, between the clear (thus no chlorophyll) epidermal layers. The epidermal layers are translucent, so light can enter. Which also allows us to see them, making the plant look green to our eyes. The area where they are is called the palisade layer, and below it, the spongy layer.The LeafWithin the leaf there are many veins, both large and microscopic, that contain no chloroplasts.A few chloroplasts are located in the guard cells around the stomata.Most sources say that there are no chloroplasts in the epidermis, though not all agree. (When studying botany, you find that there are few absolutes, because there are hundreds of thousands of different species, and nature has many ways of doing things. Just like there are some plants that have no chlorophyll or chloroplasts at all.)Plants that have green “bodies,” - if by bodies you mean the stem-like structures - have chloroplasts just below the outer epidermis of the stems, arranged similarly to leaves, which is why they look green. This would include most cacti, many succulents, the stems of annuals, vegetables and young plants, and sprouting seeds. The “body” of most cacti, and many succulents, is actually specialized stem that has taken over the major function of photosynthesis, because the leaves are so small or so changed they can no longer do it.*As you can see, beneath the epidermis are many different cell structures. Although in some plants the cells in the cortex can contain some chloroplasts, there are large areas of vascular bundles and pith or ground tissue that have no chloroplasts.The chloroplasts themselves are the food factories. They contain the chlorophyll molecules - which as you probably know gives the green color - which themselves are arranged in stacks of coin-shaped structures called thylakoids.So even inside the chloroplasts, there are cells that don’t contain chlorophyll.There are, however, within most plant cells, organelles( Learn About Plant Cell Types and How They're Like Animal Cells) called plastids. These are sort of basic building blocks that can take on different functions depending on the environmental influences. PlastidsUnder the influence of light, some of these become chloroplasts; without light, they become amyloplasts. The chloroplasts, as we know, contain chlorophyll, and are a key component in photosynthesis; the amyloplasts are found in the roots, and contain stratoliths, which help direct the root to grow downward. Under some conditions and in some plants, such as when a potato sits in the light, the amyloplasts can change to chloroplasts, which is why the potato starts to turn green. (When Is A Chloroplast Not A Chloroplast?)Technically, if you’re looking at the genetic information (DNA), all plant cells carry the information to make chlorophyll and chloroplasts. But the information only expresses itself under certain very specific sets of conditions.* Interesting side note: I looked for several hours - at least 2 or 3 - for a diagramatic sketch of a cactus stem. Couldn’t find it. What??? There may be a good subject for someone’s thesis, or special publication, if anyone out there is interested to do it.

Photosynthesis by definition 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. [1]Living things that depend on others for food are called heterotrophs. Herbivores like cows and other plant eating insects are examples of heterotrophs. [3]Living things that produce their own food are called autotrophs. Green plants and algae are good examples of autotrophs. [3]Photosynthesis sustains virtually all life on planet Earth providing the oxygen we breathe and the food we eat; it forms the basis of global food chains and meets the majority of humankind’s current energy needs through fossilized photosynthetic fuels. The process of photosynthesis in plants is based on two reactions that are carried out by separate parts of the chloroplast. The light reactions occur in the chloroplast thylakoid membrane and involve the splitting of water into oxygen, protons and electrons and in the dark reactions, the protons and electrons are used to reduce CO2 to carbohydrate. [2]Know that you know the definition of what photosynthesis is and who depends on this chemical conversion of light into energy let us explore the mechanisms at hand that provides the energy for most of the earth’s functions.Light reactions need light to produce organic energy molecules (ATP and NADPH). They are initiated by colored pigments, mainly green colored chlorophylls.[3]Dark reactions make use of these organic energy molecules (ATP and NADPH). This reaction cycle is also called Calvin Benison Cycle, and it occurs in the stroma. ATP provides the energy while NADPH provides the electrons required to fix the CO2 (carbon dioxide) into carbohydrates. make use of these organic energy molecules (ATP and NADPH). This reaction cycle is also called Calvin Benison Cycle, and it occurs in the stroma. ATP provides the energy while NADPH provides the electrons required to fix the CO2 (carbon dioxide) into carbohydrates. [3]The basic structure of the leafTo truly understand photosynthesis you must understand the physiology of a plants leaf and what mechanism contribute to the process.Wide Plant LeavesMosts green plants have leaves that are broad, flat and exposed to capture as much of the sun's energy (sunlight) needed for photosynthesis. This wide surface area allows for the maximum amount of light exposure for the process to help the plant grow.VeinsThe network of veins in the leaf also carry water from the stems to the leaves. Glucose produced is also sent to the other parts of the plant from the leaves through the veins. Additionally, the veins support and hold the leaf flat to capture sunlight.Pores (holes)The stomata (tiny holes underneath the leaf) allows air in and out of the leaf. Stomata (single is called stoma) is usually at the bottom surface of the leaf but some plant species have them on the upper surface whiles other have them on both sides.The stomata closes in the night to retain gases and moisture in the leaf cells, and opens during the day for gaseous exchange to continue.Where does photosynthesis take place?Photosynthesis takes place inside plant cells in small things called chloroplasts. Chloroplasts (mostly found in the mesophyll layer see the figure above) contain a green substance called chlorophyll. Chlorophyll absorbs the light energy needed to make photosynthesis happen. It is important to note that not all the color wavelengths of light are absorbed. Plants mostly absorb red and blue wavelengths — they do not absorb light from the green range. Below is the structure of a mesophyll cell and the other parts of the cell that work with the chloroplast to make photosynthesis happen.Cell walls: provide structural and mechanical support, protect cells against pathogens, maintain and determine cell shape, control the rate and direction of growth and generally provide form to the plant.Cytoplasm: provides the platform for most chemical processes, controlled by enzymes.Cell membrane: acts as a barrier, controlling the movement of substances into and out of the cell.Chloroplasts: As described above, simply contain chlorophyll, a green substance which absorbs light energy for photosynthesis.Vacuole: the container that holds moisture, and keeps the plant turgid.Nucleus: this contains genetic make (the DNA), which controls the activities of the cell.Conditions for successful photosynthesisThere must be light and other molecules present to have a successful photosynthesis reaction in the plant leaves and they are as follows.Carbon dioxide (A colorless, naturally occurring odorless gas found in the air we breathe. It has a scientific symbol CO2. CO2 is produced by burning carbon and organic compounds. It is also produced when plants and animals breathe out during respiration)Plants get carbon dioxide from the air through their leaves. The carbon dioxide diffuses through small holes in the underside of the leaf called stomata. (singular: stoma. plural: stomata)The lower part of the leaf has loose-fitting cells, to allow carbon dioxide to reach the other cells in the leaf. This also allows the oxygen produced in photosynthesis to leave the leaf easily.Carbon dioxide is present in the air we breathe, at very low concentrations. Even though it forms about .04% of the air, it is a needed factor in light-independent photosynthesis.In higher concentrations, more carbon is incorporated into carbohydrate, therefore increasing the rate of photosynthesis in light-independent reactions.WaterPlants get the water they need for photosynthesis through their roots. The roots have a type of cell called a root hair cell - these project out from the root into the soil. Roots have a big surface area and thin walls, which allow water to pass through them easily.Plants need water for other important things such as: it provides dissolved minerals that keep the plants healthy, a fluid a medium for transporting minerals, it keep the plant firm and upright with appropriate turgidity, it keeps the plant cool and hydrated, and allows other chemical reactions to occur in plant cellsLight (Even though both natural and artificial light is OK for plants, natural sunlight is usually great for photosynthesis because they have other natural UV properties that help the plant)A leaf usually has a large surface area, so that it can absorb a lot of light. Its top surface is protected from water loss, disease and weather damage by a waxy layer. The upper part of the leaf is where the light falls, and it contains a type of cell called a palisade cell. This is adapted to absorb a lot of light. It has lots of chloroplasts.In light-dependent reactions (as explained in light and dark reactions early in the essay), photosynthesis increases with more light. More chlorophyll molecules are ionised and more ATP and NADPH are generated as more light photons are focussed on a green leaf. Even though light is extremely important in light-dependent reactions, it is important to note that excessive light can damage chlorophyll and photosynthesis can reduce.Light-dependant reactions do not rely too much on temperature, water or carbon dioxide, even though they are all necessary for the process to complete. This means cold or hot, the reactions will occur as long as there is enough light.Chlorophyll (This is the green pigment found in the leaves of plants)Nutrients and minerals (Chemicals and organic compounds which the plant roots absorb from the soil)Resources[1]-Photosynthesis - Wikipedia[2]-Photosynthesis- Matthew P. Johnson U.K.http://essays.biochemistry.org/content/ppebio/60/3/255.full.pdf[3]-What are dark and light reactions in photosynthesis?