The rate of photosynthesis Essay Example for Free

The value of p igneousosynthesis EssayIntroductionPhotosynthesis is the trapping of peerless C dioxide and its subsequent reduction to carbohyd ordinate, using hydrogen from water system. Hexose sugars and starch be commonly formed so the fol beginninging equation is often used open-eyed energy6 carbon dioxide + 6H2O C6H12O6 + 6O2carbon dioxide water chlorophyll carbohydrate oxygenPhotosynthesis consists of two stages These are the elation-dependent reactions, for which light energy is necessary, and the light strong-minded reactionsseries of light-dependent reactions that are temperature-independent and a series of temperature-dependent reactions that are light-independent. The rate of the first series, called the light reaction, abide be increased by change magnitude light intensiveness (within authentic limits) still non by increasing temperature. In the second series, called the dark reaction, the rate keister be increased by increasing temperature (within cert ain limits) only when not by increasing light intensityPhotosynthesis involves the fruition of oxygen, and the uptake of carbon dioxide. These can be used as a measure of the rate of photosynthesis.This sample will be an investigation into the photosynthetic rate, the rate at which plants produce all their own organic substances (food) using only light energy and simple inorganic substances. The rate of photosynthesis is dependent on environmental component parts, particularly the amount of light available, the level of carbon dioxide and the temperature. The effect of these incidentors can be tested examineally by change one of these factors while holding others incessant.We know that light intensity, carbon dioxide preoccupancy and temperature are three factors that can construct up the rate of photosynthesis. If the level of one of these factors is changed, rate of photosynthesis changes. Normally, only changes to one of the factors will affect the rate of photosynthes is in a plant at a epoch. This is the factor that is nearest to its minimum, the modification factor. Changing the limiting factor increases or decreases the rate, but changes to the other factors scram no effect. This is because photosynthesis is a complex is a complex involving umteen steps. The overall rate of photosynthesis in a plant is ascertain by the rate of whichever step is proceedings most slowly at a particular cartridge clip. This is called the rate-limiting step. The three limiting factors affect antithetic rate-limiting steps. ascorbic acid dioxide assiduityAt low and medium carbon dioxide tautnesss, the rate-limiting step in the Calvin cycle is the point where CO2 is fixed to produce glycerate 3-phosphate. Ribulose bisphosphate (RuBP) and NADPH accumulate. At high(prenominal) CO2 soaking ups few other factor is limiting.Light intensityAt low light intensities, there is a shortage of the products of the light-dependant reactions NADPH and ATP. The point where glycerate 3-phosphate is subjectd is the rate-limiting step in the Calvin cycle. At high light intensities whatsoever other factor is limiting.TemperatureAt low temperatures, all of the enzymes that change state the reactions of the Calvin cycle pretend slowly. NADPH accumulates. At intermediate temperatures, some other factor is limiting. At high temperatures, RuBP carboxylase does not work effectively, so the rate-limiting step in the Calvin cycle is the point where CO2 is fixed. NADPH accumulates.Research question How does altering the carbon dioxide immersion affect the rate of photosynthesis?PredictionI predict that the rate of photosynthesis is positively cerebrate with CO2 engrossment. I predict that increasing the CO2 concentration will increase the rate of photosynthesis pro rata to it. Applied to my experiment, that centre the high the sodium hydrogen carbonate issue concentration (which provides the CO2 for the cress plant plant plant plant disks in or dination to photosynthesize), the speedy oxygen is produced as a crazy product and the faster the cress criminal records grow to the sink of the beaker.VariablesThe independent variableCarbon dioxide concentration Sodium hydrogen carbonate solution was used to provide the CO2 for the cress disks in order to photosynthesize. In the experiment different NaHCO3 concentrations were do up using pure NaHCO3 solution and distilled water, always make up 60cm3 of liquid.Controlled VariablesLight intensity A bench lamp was used as the light source in the experiment. It was always constantly placed 5cm in a higher place the liquid clear so that the same amount of light falls on the beaker with the cress disks indoors the hydrogen carbonate solution for e truly experiment.Temperature The temperature should stay constant for all of the carried out experiments, room temperature of well-nigh 20C being the case.Dependent variableAmount of oxygen as a screw up product of photosynthesis p roducedIn the experiment we didnt measure the amount of oxygen produced directly. Instead a stop date was used to monitor how vast it took for the individual cress disks to rig out to the top of the beaker. Being the dependent variable, the cartridge clip it took for cress disks to derail at different NaHCO3 concentrations, was the recorded data. In the experiment the NaHCO3 solution enters the air spaces of the cress disks. As it provides the cress disks with the CO2, say the higher the NaHCO3 concentration meant the more oxygen is produced as a waste product of photosynthesis. The quicker the cress disks rose to the top of the beaker means that more oxygen is produced during photosynthesis.Apparatus1 Plastic stem3 Small Beakers (100cm)2 Plastic Syringes (20cm)1 Plastic Syringe (10cm)1 stopwatch1 Thermometer1 cress plantMethod1. Use a credit card straw to punch out 5 magnetic disks from the seed ruffles of the cress plants provided. Do this by placing a finger infraneath the cotyledon to support it. Keep the phonograph recordings in the straw for the moment.2. The plunger from a 10cm3 credit card spray was removed. Then I placed a finger over the nozzle and approximately half-filled the syringe with sodiumhydrogen carbonate solution. Gently blow the discs from the straw into the syringe. I replace the plunger, inverted the syringe and then pushed the plunger up far enough to expel the air from the syringe.3. Place a finger over the nozzle of the syringe and gently pull out the plunger a short distance (past a 3cm3 distance on the syringe barrel). This execution was done in order to pull the air out of the air spaces of the cress discs and replace it with the surrounding solution. I had to hold the plunger at this position for a few seconds to process sure the air really gets pulled out the discs air spaces, and then removed my finger from the nozzle.4. Repeat this procedure twice more. Tap the syringe barrel between for each one evacuation. A t this stage the discs should sink. If this does not lapse repeat the evacuation process.5. Use pure sodium hydrogen carbonate solution and distilled water in order to always make up 60cm3 liquid of different NaHCO3 concentrations Using two 20cm3 plastic syringes for each the pure sodium hydrogen carbonate solution and the distilled water, the needed quantities are disposed into a beaker to make up the wanted NaHCO3 concentrations.6. Then the syringe plunger was removed and the contents are tipped into the beaker.7. go steady that the discs have sunk to the bottom and if not remove and discard those ones. A minimum of 4 deep-set discs is required in order to have sufficient data for the experiment.8. The beaker with the contents is placed immediately to a start out place a bench lamp. This has to stand not more than 5 cm above the solutions surface but so that it still allows one to see the discs.9. The bench lamp is turned on and the stopwatch is started. The discs are obser ve until they have all risen to the surface. The sentence in seconds it takes for each disc to rise is recorded.10. This procedure is ingeminate using different concentrations of sodium hydrogen carbonate solution.ResultsThe following tables show the amount of cadence (in seconds) it took for the discs low different NaHCO3 concentrations to rise to the water surface. Every experiment was done twice in order to bill for reliability of the first results.Time taken in seconds for discs to rise in 10 cm of NaHCO310 cm pure NaHCO3 solution + 50 cm H2O maiden reading per seconds second in seconds Average insecondsdisc 1 524 502 513.0disc 2 592 575 583.5disc 3 642 618 630.0disc 4 680 658 668.5disc 5 767 698 732.5Time taken in seconds for discs to rise in 20 cm of NaHCO320 cm pure NaHCO3 solution + 40 cm H2O world-classexperiment in seconds 2nd in seconds Average inseconds .disc 1 387 362 374.5disc 2 428 401 414.5disc 3 470 452 461.0disc 4 502 486 494.0disc 5 544 587 565.5Time taken in seconds for discs to rise in 30 cm of NaHCO330 cm pure NaHCO3 solution + 30 cm H2O 1st experiment in seconds 2nd in seconds Average insecondsdisc 1 265 282 273.5disc 2 279 336 307.5disc 3 360 398 379.0disc 4 446 458 452.0disc 5 507 532 519.5Time taken in seconds for discs to rise in 40 cm of NaHCO340 cm pure NaHCO3 solution + 20 cm H2O 1st experiment in seconds 2nd in seconds . Average insecondsdisc 1 313 301 307.0disc 2 354 360 357.0disc 3 378 401 389.0disc 4 428 476 452.0disc 5 487 498 492.5Time taken in seconds for discs to rise in 50 cm of NaHCO350 cm pure NaHCO3 solution + 10 cm H2O 1st experiment in seconds 2nd in seconds Average insecondsdisc 1 263 282 272.5disc 2 287 299 293.0disc 3 343 318 330.5disc 4 398 419 408.5disc 5 456 443 449.5Time taken in seconds for discs to rise in 60 cm of NaHCO360 cm pure NaHCO3 solution 1st experiment in seconds 2nd in seconds Average insecondsdisc 1 259 245 252.0disc 2 265 271 268.0disc 3 303 288 295.5disc 4 313 302 295.5disc 5 319 311 315 .0Table showing 1/time for the different NaHCO3 solutions (CO2 concentration)1st runConcentration of CO2 (NaHCO3 solution in cm3) 1 / time it takes for disc 1 to rise to surface in seconds 1 / time it takes for disc 2 to rise to surface in seconds 1 / time it takes for disc 3 to rise to surface in seconds 1 / time it takes for disc 4 to rise to surface in seconds 1 / time it takes for disc 5 to rise to surface in seconds Average of 1 / time for the 5 disksConcentration of CO2 (NaHCO3 solution in cm3) 1 / time it takes for disc 1 to rise to surface in seconds 1 / time it takes for disc 2 to rise to surface in seconds 1 / time it takes for disc 3 to rise to surface in seconds 1 / time it takes for disc 4 to rise to surface in seconds 1 / time it takes for disc 5 to rise to surface in seconds Average of 1 / time for the 5 disksAverageConcentration of CO2 (NaHCO3 solution in cm3) 1 / time it takes for disc 1 to rise to surface in seconds 1 / time it takes for disc 2 to rise to surface i n seconds 1 / time it takes for disc 3 to rise to surface in seconds 1 / time it takes for disc 4 to rise to surface in seconds 1 / time it takes for disc 5 to rise to surface in seconds Average of 1 / time for the 5 disksComments on resultsAs one can see from the tables, in world-wide the time it takes for the cress discs to rise to the surface of the beaker decreases as the concentration of NaHCO3 increases. In average, when 10cm3 of NaHCO3 where used, disc 1 rose after 513.0 seconds, disc 5 after 732.5 seconds. When 60cm of NaHCO3 where it took only 252.0 seconds for disc 1, and 315.0 seconds for disc 5 to rise. The basic class that as NaHCO3 concentration increases the time for the discs to come to the top decreases can be seen.This would mean that more oxygen is produced by the leaf discs as NaHCO3 concentration increases, and as a result the time to rise to the top decreases. As oxygen production can be used as a measure of photosynthesis, in taking the time of how long it t akes for the discs to come to the surface, we get values that are relative to the oxygen production. One can and then calculate the rate of photosynthesis by dividing 1 over the average time it took for the discs to rise to the top. From the results table above the general pattern that the rate of photosynthesis increases as the concentration of CO2 (NaHCO3) is raised.At a CO2 concentration when 10cm3 NaHCO3 are used the rate of photosynthesis is 0.0016223. At a CO2 concentration when 60cm3 NaHCO3 are used the rate of photosynthesis is 0.00352848.However the table shows that at a CO2 concentration when 40cm3 NaHCO3 were used the average rate is 0.0025744 which is lower than at 30cm3 NaHCO3 which gave a rate of 0.00273684. This explains the little dink in the graph at the CO2 concentration of 40cm3 NaHCO3 before the line continues to go up again from a CO2 concentration of 50cm3 NaHCO3.The graph very well displays that the rate of photosynthesis increases fairly quickly as the CO2 concentration is increased and that the line is get-go to level send by at higher CO2 concentrations.AnalysisMy results clearly show that the average time it takes for the cress discs to rise decreases as the concentration of NaHCO3 increases. This is because the higher the CO2 concentration the higher the rate of photosynthesis. As a result of the photosynthetic rate increasing, the production of oxygen as a waste product of photosynthesis increases as well. As the cress discs produce oxygen quicker at higher CO2 concentrations that means the oxygen will make the discs rise quicker. With more oxygen produced the buoyancy of the cress discs increases and this leads to the discs floating to the top of the beaker. With the discs rising faster and indicating that the amount of oxygen produced increases with higher CO2 concentration, will mean that the rate of photosynthesis increases as well.My results support this statement, too. My graph shows that at low to fairly high CO2 concen trations the rate of photosynthesis is positively fit with CO2 concentration. This implies for my graph except for the CO2 concentration of 40cm3 which is so clearly an anomalous result. The graph withal shows that at high CO2 concentrations the rate of photosynthesis is slowing down and moving towards a plateau. This is because at high CO2 concentrations there is some other factor limiting the rate of photosynthesis.ConclusionIn general my results support my hypothesis that the rate of photosynthesis is positively related with CO2 concentration. My results from experiment have shown that at higher CO2 concentrations more oxygen is produced by the cress discs. This oxygen will make them rise to the surface more quickly as the leaf discs buoyancy increases.My results table and graph show that at constant light intensities and temperature, the rate of photosynthesis initially increases with an increasing concentration of carbon dioxide, but is starting to reach a plateau at higher concentrations. At low concentrations of carbon dioxide, the supply of carbon dioxide is the rate-limiting factor. At higher concentrations of carbon dioxide, other factors such as light intensity and temperature are rate limiting.The rate of photosynthesis is determined by the rate-limiting step which is the step that is proceeding most slowly at a time. At low to medium CO2 concentrations, the rate-limiting step in the Calvin cycle is the point where CO2 is fixed to produce glycerate 3-phosphate. RuBP and NADPH accumulate. The plateau on my graph however shows that at higher CO2 concentrations some other factor is limiting, implication either light intensity or temperature are too low for the rate of photosynthesis to increase further.To the uttermost that the rate of photosynthesis increases as the rate of CO2 concentration increases, my prediction overlaps with my results. However my results have also shown me the fact that this relationship doesnt continue like that forever. Having done this experiment, has shown me that the rate of photosynthesis increases with increasing CO2 but is limited by the factor which is nearest to its lowest value.Accuracy of observationsIn general, the accuracy of the equipment is very good, however, for each of them there is some element of inaccuracy in terms of the readings to be made this also includes the human element in making the reading. For the mostaccurate results, the reading has to be made with the scale being on eye level.The 20cm plastic syringes have an accuracy of + 0.5cm3 the beakers as well show an accuracy of + 0.5cm3. The 10cm3 syringes however are accurate to + 0.25cm3 consequently for all the solutions we have to assume that the maximum error of the readings made could be + 1.25cm, which is very important.Improvements to method thus far though, the method could be remedyd still. One issue for instance that could be used to slightly improve the method and thus the accuracy of the results would be to u se a water bath in order to make sure that the experiment is conducted under generally stable conditions as for this will ensure that the temperature be the same end-to-end the whole experiment. This would be of great importance for conducting an experiment which implies of temperature being one of the limiting factors. Using a water bath one could also set up the experiment in a way that the oxygen produced as waste product of photosynthesis could be directly cleared under water.Evaluation and anomalous resultsIn general the method wasnt changed much to the preliminary work. However, in my preliminary work I first used a total amount of 100cm3 NaHCO3 solution to make up the different NaHCO3 concentrations. This showed that when low NaHCO3 concentrations (little pure NaHCO3 being used) were used, it took more than 10minutes for the cress discs to rise to the surface of the beaker. This is simply too long and wouldnt have given me enough time to do sufficient repeats of the experi ment. Thats why I decided to reduce the total amount of NaHCO3 solution used to 60cm3.I think that my results have shown that a general pattern can be seen. The collected data, illustrated in tables and diagrams backs up my prediction.However the reliability is not too strong, as significant differences can be seen in the time taken for the discs to rise, especially at a NaHCO3 concentration of 40cm3.Throughout the experiment the same plastic straw was used to cut discs out from cress leaves. The plastic straw had a diameter of more or less 4mm, meaning that all cress discs had the same diameter throughout the investigation. However other variations in the size of the cress discs could have occurred. For example the thickness of the cress leaves competency have varied, resulting in thicker and thinner and cress discs between experiments. These structural differences might have accounted for the anomalous results but also for the significant differences in the time it took for the discs to come up to the surface, between run 1 and 2 of the same concentration.A factor that wasnt particularly controlled at all was temperature. The light source of the investigation was a simple bench lamp. As I have observed the light bulb got really hot after a few minutes of usage. This would mean that at the beginning, namely the very first concentration of the first experiment wouldnt have been affected by the light bulb. However by the time the conterminous concentration was used the light bulb was already hot. This would have resulted in the heat that given off by the light bulb to increase the temperature of the NaHCO3 solution the seed discs were floating in.Even further as the time it took for discs to rise varied with different NaHCO3 concentrations means that the time the NaHCO3 solution exposed to the heat given off by the light bulb varied, too. This means the temperature of the different NaHCO3 solutions must have varied as well. As temperature is one of the limit ing factors of photosynthesis this could have had significant effects on the experiment. Temperature being higher at some NaHCO3 concentrations means that the reaction of photosynthesis must have taken place faster, resulting in a faster production of oxygen, meaning that the cress discs rose to the surface quicker.In addition there are some anomalous results found in the graph. However, the graph shows a trough at a CO2 concentration of 40cm NaHCO.This should not be the case the line should go up further and then level off properly. My graph however doesnt show a clear plateau which should be seen when high CO2 concentrations have been reached as slowly no more oxygen can be produced in the same time. optimally at low to fairly high CO2 concentrations the graph should show that the rate of photosynthesis is directly proportional to CO2 concentration.These factors could be down to the fact mentioned earlier that the cress discs might have been of different structures, e.g. thicker a nd therefore affected the experiment.However I think that one also has to consider the fact that the experiment mired living organisms. Just like human beings, plants dont always act in an expected way. This is what essentially makes biology interesting in that the expected is not always happening.In doing this experiment we were measuring the time it took for cress discs to rise to the surface of a beaker at different NaHCO3 concentrations. In doing so we were effectively trying to collect data, namely time, which is proportional to the production of oxygen of the seed discs in order to get information about the rate of photosynthesis. The seed discs producing more oxygen meant that they would rise faster. Oxygen being a by-product of photosynthesis can be used to get a picture of the rate of photosynthesis of a plant. So ideally an experiment carried out measure the amount of this oxygen production would be better designed to get an reference of the rate of photosynthesis of a plant. The oxygen collection would take place in water a water bath could be used for example.