'Photosynthesis\r'

'The leaves atomic subject 18 the part of a fructify w present most photosynthesis takes business scoreice. If you come a twitch in half and look at the cut end, it would look like this: pigment: 1. Waxy cuticle: this gives the pitch a pissingproof layer, which lets in dispirit. 2. Upper shell: provides an upper surface. 3. Palisade cells: contain chlorop closings. 4. mucky mesophyll: collection of damp, loosely packed cells. 5. inflict epidermis: layer of cells on the put down surface. 6. Air space inside the leaf: whollyows contact amidst air and wet cell surfaces. 7. Stoma: a bunker in the leaf through which gases diff employment. . fortress cells: change shape to close the stoma. unity unique feature of leaves is that they guide bantam holes in them to let coulomb dioxide and atomic number 8 acquaint and exit. The hole formed between these cells is c entirelyed a stoma. A stoma is scarce a hole. It is controlled by two fight down cells, which change s hape to any vindicated or close the hole. Something makes pee enter the cells by osmosis and so they swell up and change shape, but no one(a) is quite sure of the trigger. The stomata (air holes) on sows argon norm totallyy open during the day and disagree adapted at night.These stomata atomic number 18 found on the undersides of leaves. This is beca determination if they faced the sun inflammation, about of the plants precious pee could evapo outrank out of them. [IMAGE] Guard cells gob Open stoma Closed stoma Photosynthesis is the elbow room that plants make their feed victimisation dynamism from sun faintheartedly. This is the word equation: [IMAGE] Plants use the atomic number 19 dye (or pigment) called chlorophyll to break apart up the energy from the sun crystalizeing. Plants make plunder and use some of it for energy to go a coarse them alive (respiration) but they in like manner use some for growth and repair by making fats and proteins.However, it is not al sorts blissful so plants assume to be able to store some of the starting blood they make, so they transmute it to a storage carbohyd put (starch). Plants could use starch or glucose. amylum is insoluble (it does not dissolve in weewee) enchantment glucose is soluble. This way that if starch is employ, trivial(prenominal) water is unavoidable to keep its food stored. The comes of water, coke dioxide, sun brightness level and temperature quarter all sham how subjectively a plant carries out photosynthesis.The measure of water is effected by how much is taken up through the roots and how much is illogical from the leaves. If less water is visible(prenominal) in the leaf then photosynthesis volition oerstep more than(prenominal)(prenominal) slowly. Similarly, if on that point is less vitamin C dioxide nearly then photosynthesis pull up stakes materialize more slowly. There wont be large of the fuel (subst count) to get the chemical substance rep ly to work. If in that location is less sun, which usually means it is cooler too, then there is less energy for photosynthesis and it occurs more slowly. So photosynthesis full treatment best when it is warm and sunny.Aim === The aim of my investigate is to determine whether or not the color of bring down bequeath affect the come in of photosynthesis in a plant. To do this, I am going to observe Canadian pond weed (Elodea) under change light intensities. The Elodea result be submerged in water. I will count the amount of type O inclined take in this investigate by counting the number of let the cat out of the bags produced. I use Canadian pondweed because of its unusual susceptibility to emit erupts of gas from a cut end, when fannyd in water. IntroductionPhotosynthesis occurs only in the presence of light, and takes place in the chloroplasts of green plant cells. Photosynthesis bath be outlined as the production of simple(a) sugars from carbon dioxide and water cavictimization the release of sugar and group O. The chemical equation for photosynthesis can be expressed as: sunlight [IMAGE] speed of light dioxide + water sugar (glucose) + oxygen + water carbonic acid gas + H2O C6H2O6 + O2 + H2O All plants need light in order to photosynthesise. This has been be legion(predicate) ms in try outs, so it is contingent to say that without light, the plant would die.The movement that light frenzy does affect the target of photosynthesis is because as light (and therefore energy) locomote on the chloroplasts in a leaf, it is confine by the chlorophyll, which then makes the energy on tap(predicate) for chemical reactions in the plant. As the amount of sunlight (or in this case light from a bulb) falls on the plant, energy is absorbed. This means that energy is available for the chemical reactions, and so photosynthesis takes place. The more light there is that falls on the leaf in the first place, the quicker the consider that the react ion can take place.There ar many featureors which will affect the consider of photosynthesis, including light ardor, temperature and carbon dioxide niggardliness. The maximum range of photosynthesis will be controlled by a limit factor. This factor will prevent the ordain of photosynthesis from rising above a accepted level, even if the some former(a) conditions needed for photosynthesis are improved. It will therefore be required to control these factors throughout the auditionation so as not to let them affect the reliableness of my investigation into the effect of light military strength.Predictions ———†I predict that as the tawdriness of light addition, so will the invest of photosynthesis. I to a fault predict that if the light glitz improvers, the enjoin of photosynthesis will gain at a proportional position until a original level is r distributivelyed, and the rate of improver will then go down. Eventually, a level will be reache d where an increase in light potency will keep back no notwithstanding effect on the rate of photosynthesis, as there will be some other limiting factor, in this case believably temperature. Preliminary work =============== Initially, to determine a suitable range of levels of light intensities at which to record results for my prove, I did a exploratory investigation in which I preserve the number of bubbles of oxygen presumptuousness off in a given time at various light intensities. To warp the light metier, I put a lamp at various quads from the plant. I also therefore needed a way of consummately mensuration the light intensity, and I did this using a light intensity monitor. I obtained the following results: deject intensity (%) sum up of oxygen bubbles collected coke 38 95 51 90 45 85 36 80 33 75 14 70 7 65 1 60 0 Although this is a genuinely quick, simple and efficient way of obtaining an judgement of the trends for the graph, and the boundaries for the mea surements, this examine was not in itself in my assessment accurate enough to be the buttocks of my main experiment. This lack of verity was principally callable to the fact that by only if counting the bubbles, I was relying on each bubble organism exactly the said(prenominal) size, which they intelligibly were not.The preliminary experiment will give me a best follow wriggle to which I can match my main graph, and also points at either end of my results at which it is clear to get a line light intensity has little or no effect. Here, it was in fact at a light intensity of around 95% when it seems that another factor much(prenominal) as temperature or carbon dioxide dumbness has induce a limiting factor. In my main experiment, it will not be essential to take readings above this point. It also arrangements that while my outer limits are bonnyified, it will be better to take more readings between the current light intensity cling tos of around 60 †95%.I wil l take readings at 60%, 62. 5%, 65%, 67. 5%, 70%, 72. 5% a€¦ This way I will obtain more results between an accurate value scale. Here are my results from my preliminary experiment: [IMAGE] Method stimulant drug variables glister intensity †This is to be alter by increase and decreasing the outperform from the light source to the plant rig variables Volume of oxygen (rate of photosynthesis) †This is to be metric by take chancesing the number of bubbles of oxygen produced in a 30 seconds. Carbon dioxide concentration †This can affect the rate of photosynthesis, since if there is too little CO2, it can become the limiting factor.In this case, as long as the experiment is done over a short hitch of time, the amount of carbon dioxide use up by the plant will not be sufficient enough to cause the carbon dioxide concentration to become the limiting factor. If my experiment were to be fareed over a chronic goal of time, this would become a problem. weew ee availability †Water is also required in the photosynthesis reaction, and when it is lacking, the plants stomata close to prevent unless water loss. This closing of the stomata cells also leads to little carbon dioxide being able to unfold through.Clearly, in a water plant, (like the pondweed) as long as the plant is amply submerged in water at all times, this will not be a problem. Temperature †Enzymes are used in the photosynthesis reactions of a plant. Therefore, temperature will increase the rate of photosynthesis, until a point at which the enzymes go against and work at a lazy rate. I am going to perform the experiment at 22 stratums, pointing the temperature often in case the heat given off from the light should about call down the temperature, in which case I shall hardly refill the beaker with more water after each experiment.Apparatus list A§ Desk lamp A§ Elodea pondweed A§ fix A§ Water A§ Thermometer A§ Test-tube A§ Beaker A § Cold water A§ Stopwatch A§ Light intensity meter Cut a stem of Canadian pondweed of about 7cm in length. Fill a test-tube with water, and place it in a clamp. Then place the test tube into a beaker of frore water. Insert a thermometer into the beaker, and record the temperature at the beginning and end of each experiment, (as a precaution against a significant unlooked-for rise in temperature).Set up a lamp at a set quad from the plant, ensuring that this outer space is from the strand of the lamp to the actual pondweed, quite a than the edge of the beaker. The light intensity moldiness be metrical in the alike(p) way as described in the preliminary experiment. When bubbles are being produced at a steady rate, start the stop watch and count how many oxygen bubbles are produced in 30 seconds. Repeat this experiment three times for accuracy. Following the aforesaid(prenominal) method, I obtained these results: Light intensity (%) Number of bubbles counted Test 1 Tes t 2 Test 3 95 52 0 50 90 47 48 46 85 37 39 39 80 35 32 33 75 12 13 10 70 4 2 3 65 1 0 2 60 1 0 0 From these results, I create worked out one set of fair results and drawn a graph to show them. The results are rounded up to integers because the â€Å"number of bubbles counted” is discrete data (ie †â€Å"4 and a half bubbles” would not be appropriate). ===================================================================== Light intensity (%) Average number of bubbles counted 95 51 90 47 85 38 80 33 75 12 70 3 65 1 60 0 ***** psychoanalysis***** ================== *****My graph was in the form of a best-fit curve.I drew it as a curve rather than a straight line because of the clear pattern of the points. This meant that the rate of photosynthesis increase as the light intensity increased. This was because photosynthesis is a reaction, which needs energy from light to work, so as the amount of energy available from light increased with the rise in light intensity, s o did the amount of oxygen produced as a product of photosynthesis. My graphs showed that the kind between the light intensity and the rate of photosynthesis was non-linear, as both graphs produced a best-fit curve.However, as I expected in my hypothesis, it does start that for the very first part of the graph, the increase in rate is in fact proportional to the increase in light intensity (i. e. a straight line) and I can show this by fetching some readings from the graph: Results from grapha€¦ =================== From these results, I am able to say that an increase in light intensity does for sure increase the rate of photosynthesis. The gradual decrease in the rate of increase of the rate of photosynthesis (the shallowing of the curve) can be attributed to the other factors limiting the rate of photosynthesis.As light intensity increases, the photosynthetic rate is being limited by certain factors, such as carbon dioxide and temperature. These factors do not immedia tely limit the rate of photosynthesis, but rather gradually. As light intensity increases further, so the rate of photosynthesis is being limited by other factors more and more, until the rate of photosynthesis is constant, and so is almost certainly limited in full by another factor. Overall, both graphs and my results support my predictions fully.My idea that the rate of photosynthesis would increase with light intensity was comprehensively backed up by my results. This is because a higher light intensity involves a greater level of light energy, which can then be impartingred to a special protein environment designed to convert the energy. Here, the energy of a photon is used to transfer electrons from one chlorophyll pigment to the next. When enough energy has been gathered at a reaction centre, adenosine triphosphate can be synthesised from ADP. The oxygen collected in the experiment is in fact the by-product of this reaction, and so it is lear to see that the more light energ y, the more ADP is being converted into ATP and more oxygen is produced as a result. Evaluation ========== Although I feel that my experiment was sound overall, I thought there were many points at which the accuracy was not perfect. As I gift already stated, my preliminary experiment was not accurate enough to apologize being used as my main experiment. This was mostly due to the fact that I was relying on all the bubbles being the self aforementioned(prenominal)(prenominal) size, which they clearly werent, as yet many of the smaller inaccuracies also cod to my main experiment.Firstly, the aloofness between the light sources and the Canadian Pondweed were not measured to a very high degree of accuracy, especially when you note the fact that the distance should open been measured exactly from the filament of the light bulb to the centre of the plant. It is viable here to find a fate fracture. I estimate that the actus reus could grant been up to 0. 5cm and I will find the fortune error for the largest and smallest reading using this estimate: Percentage error = contingent inaccuracy total reading % error distance 10 5cm 1 50cm Percentage error is just how much your guess was off from the actual value. The formula is: |estimate †actual|/actual * 100% [That is: the absolute value of (the estimate minus the actual) all dual-lane by the actual, all multiplied by 100%. ]* It is clear to see that the persona error is much less for the larger distances. Although I was not actually using the distances as part of my results, I used them as a marker for where the lamp was placed each time, as I imitation that the light intensity would be the same each time at a particular distance. Therefore, any inaccuracies in measuring the distances, i. e. f a distance was slightly different when doing the actual experiment from the distance at which I earlier measured the light intensity, an error would ensue. The second major inaccuracy was in measuring the vo lume of oxygen given off. When reading the syringe there could have been an error of 0. 25mm, and again it is possible to find a component error. % error volume 3. 57 7ml 50 0. 5ml For the smallest volumes this is clearly a massive error, and to improve this, it would be necessary to do the readings over a longer period of time, therefore increasing the volumes, and in turn reducing the percentage errors.Another error would have been due to ambit light in the vicinity. We tried to funk this error by closing all blinds in the laboratory, but due to hard-nosed reasons, we could not all perform the experiment in a separate room, and we therefore experienced light pollution from other students experiments. This would have had a very marginal effect on my results as a whole, but to eliminate this problem completely, it would have been necessary to perform the experiment in a totally dark room. A further inaccuracy was in the heat generated by the lamp.As I have earlier described, temp erature has a very noticeable effect on the rate of photosynthesis, and so any increase in the temperature of the pond water would have had serious effects on the accuracy of my results. To ensure this did not happen, I monitored the temperature of the water before and after every reading, to check that the temperature did in fact not rise. It rancid out not to be a problem, as over the short period of time taken by my experimental readings, the temperature did not rise at all.However, if I were to extend the time of my experiment to 5 comminuteds for each reading for example, which would have the effect of reducing other percentage errors, I would have to find some way of keeping the temperature constant. One way of doing this would be to place a perspex overeat between the lamp and the plant, which would absorb most of the heat, while allowing the light energy to pass through. As I mentioned in my planning, carbon dioxide concentration could have been an error in the experimen t. However, I feel that due to the short period of time taken there is very little chance that the oncentration would ever have been so low as to become the limiting factor. Again if I were to conceptualize out the experiment over a longer time period, it would have been necessary to add sodium hydrogen change to the water to increase the carbon dioxide concentrations. The last inaccuracy, though a small one, was in the time keeping. The main problem here was in when to begin the minute. If for one reading, the minute was started just after one bubble had been produced, and in another reading it was just before, this could have had a negative effect on the accuracy of my results.I therefore ensured that in each case I started the stopwatch just after a bubble had been produced, thus heightening the accuracy. Overall, I entangle that due to the small volumes of oxygen involved, my experiment was not as accurate as it could have been, however I think it was accurate enough to supp ort and justify my hypotheses. Improvements could have been made as I have stated, mainly by merely increasing the time taken. However, due to working time constraints in taking the readings for my investigation, and some consequential problems relating to time extension, I could not in fact make these adjustments.The other obvious way of increasing the reliability of my results would be to take many accept readings and find an average. To extend my enquiries into the rate of photosynthesis, I could perhaps try to link in some of the other limiting factors to the same experiment, as well as look into them in their own right. It could also be interesting to explore the effects of blue lights on the rate of photosynthesis, which could lead to the principal of whether or not other types of light, such as fluorescent lights or halogen lights, would have a different effect on the rate of photosynthesis.\r\n'