Example research essay topic: Factors That Affect Light Energy - 2,125 words

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Investigation Into The Factors That Affect The Investigation Into The Factors That Affect The Rate Of Photosynthesis In Elodea Investigation into the factors that affect the rate of photosynthesis in Elodea Introduction? ? Photosynthesis is the chemical process, which takes place in every green plant to produce food in the form of glucose. ? Plants use the suns energy to join together water and carbon molecules to make the glucose, which is sent around the plant to provide food. ? Cells in the root or stem can use the glucose to make energy, if the plant does not need to use all the glucose immediately then it is stored which is difficult because glucose is hard to store in water. ?

Plants solve this problem by joining hundreds of glucose molecules together to make starch. ? Starch does not dissolve in water very well so it makes a better food store. ? Photosynthesis takes place mainly in leaves and depends on an important green pigment called chlorophyll, which is found in chloroplasts. ? To obtain the most sunlight as possible, leaves have a large surface area and the more sunlight the plant receives, the better it can photosynthesize. ? Chloroplasts are found in palisade cells in large numbers and to allow as much light to get in as possible, the cells are arranged like a fence. ? This helps the energy entering the surface of the leaf to travel a long way through the palisade cells. ?

Glucose can provide energy or carbon, which can manufacture other molecules in the plant. ? Which can make new living matter and this is called biomass. ? The chemical equation for photosynthesis is: ? ? ? ? ? ? ? ? ? ? ? Carbon dioxide + Water? ? ? = ? ? Glucose and Oxygen? ? ? ? ? ? ? ? ? ? ? 6 CO 2? +? 6 H 20? = ? C 6 H 1206? +? 6 O 2 Key Factors: ?

CO 2 is vital in photosynthesis because the plant takes in CO 2 from the air and joins with water molecules to make glucose. ? The CO 2 comes in through the stomata pores on the surface of the leaf and only 0. 03 % of the air around is CO 2 so it? s pretty scarce. Temperature has to be kept at a certain level because if it gets too hot, about 45 'C then the enzymes in the chlorophyll will be killed and photosynthesis will stop altogether. ?

If the temperature is too cold then temperature becomes a limiting factor and the enzymes will stop working. Light As chlorophyll uses light energy to perform photosynthesis, it can only do it as fast as the light is arriving. ? Chlorophyll only absorbs the red and blue ends of the visible spectrum but not the green light in the middle, which is reflected back. ? If the light level is raised the rate of photosynthesis will increase steadily but only to a certain point.

Water is important because it is needed to join with CO 2 molecules to make glucose and the amount of chlorophyll needs to be enough so that the plant can photosynthesize to the best of its abilities. Investigation Prediction I predict that the plastic sheets coloured green, yellow and orange will produce the least amount of bubbles because the light will be transmitted. ? Whereas placing red and blue sheets in front of the Elodea will result in the greatest amount of bubbles because the light is absorbed. ? Certain colours of light can limit the rate of photosynthesis depending on how well it is absorbed into the plants chlorophyll to photosynthesize. ?

Also the wavelength can change the rate of photosynthesis. ? If the lamp supplying heat for the plant were placed twice as far away, I predict that there would be half as many bubbles. ? Also if it were moved twice as far closer then there would be twice as many bubbles. ? This is backed up with knowledge from previous experiments and ones done by other people and scientific understanding. Diagram? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Previous experiment Method?

For our experiment we chose as accurate equipment as possible to give us the most accurate results. ? The equipment is as follows: ? 1 lamp? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? A boiling tube? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? A small piece of Elodea? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Plastic sheets of different colours? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?

A beaker The boiling tube was filled with water and the Elodea placed in. ? The boiling tube was placed in the beaker and the lamp placed at a set length away. ? He plastic sheets were individually wrapped around the beaker with an elastic band. ? For every new plastic sheet we counted the number of bubbles each time for a minute. ? It was important to keep the experiment the same each time to ensure it was fair test for example: The lamp stayed the same distance from the beaker, we used the same plant each time and the plastic sheets were all the same size. ?

The experiment was repeated three times and the results were averaged to ensure they were regular and as expected. ? Results were recorded each time and patterns observed. ? Previous results for an experiment of this kind have been recognized and compared. ? Throughout the experiment we made observations for a number of distinctive things: ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? · ? ?

Increase/Decrease in bubbles? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? · ? ? Temperature Increase/Decrease · ? ? Change in Elodea · ? ? Size of bubbles Variables include: ? ? ? ? ? ? ? ? ? · ? ? Length of Elodea · ? ? Amount of water · ? ?

Distance of lamp · ? ? Size of boiling tube · ? ? Transparency of sheets · ? ? Time spent counting Changing either of the variables would have had effects on the end results; we kept ours all the same each time to ensure a fair test. Results Coloured sheet Red Orange Yellow Green Blue White No. of bubbles 50 5 1 4 39 17 Repeat 1 45 2 0 0 41 10 Repeat 2 47 1 1 0 35 12 Average 47. 333333 2. 6666666 0. 6666666 1. 3333333 38. 333333 13 As predicted, the results conclude that using sheets with colours near the red and blue end of the spectrum produce a higher amount of bubbles than those near green. ?

Thereby proving that photosynthesis is increased with certain colours of light. Conclusion/Evaluation? In observation of the results, I have seen how the rate of photosynthesis in the Elodea has been affected by the various factors. ? In reference to the prediction, I was correct in that the red and blue coloured sheets produced the highest rate of photosynthesis, whereas the sheets, which were green and yellow, resulted in the least bubbles. ? I feel that we had taken enough measurements to be sure of a fair test as the experiment was repeated several times so. ? Each plastic coloured sheet we used had the same time, and variables as the others so we obtained precise results for every test. ?

We did not find anything, which stood out too much from the pattern except that the red plastic sheet, when used resulted more bubbles generally than the blue sheet. ? This shows that chlorophyll absorbs red light more easily than blue. ? We acquired similar results with each repetition and found ours to be similar to previous experiments. ? The Elodea produced more bubbles with sheets at each end of the spectrum because the chlorophyll in the plant absorbs all the colours but transmits green. ? When the light is absorbed the plant converts it into energy to photosynthesize. ? The more light energy it receives the better and faster it can do this so when the sheets near the blue and red parts of the spectrum are held in front of the Elodea it absorbs the light and can photosynthesize better. ?

If plastic sheets are held up which are have a colour near the green part of the spectrum then the light will be transmitted and the plant will not be able to photosynthesize as well. ? In this experiment we have covered the main colours of the visible spectrum and they are sufficient to produce the results that we are looking for. If we were to repeat the experiment then there are several ways we could improve it. ? For example to get around the problem of the heat from the lamp producing more bubbles then a thick glass panel could be placed in the middle to prevent any heat reaching the Elodea. ?

To improve the accuracy of counting the bubbles, you we could only count the ones, which are a certain size, and only the ones coming from the very end of the Elodea. ? If there were lots of people counting the bubbles and the results averaged then that would be a more accurate way of obtaining the information necessary. ? To extend the investigation you could change certain variables for example the type of plant that you are using to count the bubbles from. ? You could try an entire species of plant and see if the results are similar for every type. You could use different chemicals in the water each time to see which chemicals result in the greatest rate of photosynthesis.

Research essay sample on Factors That Affect Light Energy