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Investigation to find does light intensity affect the stomata density of leaves.

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Investigation to find does light intensity affect the stomata density of leaves. Aim: To find out that does light intensity affect the stomata density of leaves. Leaf stomata are the main means of gas exchange in vascular plants. Stomata are small pores, typically on the undersides of leaves, which open or close under the control of a pair of banana-shaped cells called guard cells. When open, stomata allow carbon dioxide to enter the leaf for synthesis of glucose, and also allow for water, and free oxygen, to escape. In addition to opening and closing the stomata, plants may exert control over their gas exchange rates by varying stomata density in new leaves when they are produced. The more stomata per unit area the more carbon dioxide can be taken up, and the more water can be released. Thus, higher stomata density can greatly amplify the potential for behavioural control over water loss rate and carbon dioxide uptake. Prediction: I think that from the top section of the bush will have more stomata present. I think this is because light stimulates the stomata's to open, and at the top of the bush the leaves are receiving the most light. For photosynthesis to happen the plant needs sunlight and carbon dioxide, so there are more stomata present there to take in the carbon dioxide they need for photosynthesis. I think that at the bottom section of the bush there will be less stomata present, because there is less light reaching the leaves, so there ...read more.


I measured the light intensity using a luxmeter from the different sections of the bush, from where the leaves were taken from. So that I know how much light is received by the leaves in those sections. I did all the experiment in one day, so that it was a fair test, because then the weather would be the same, the condition for the leaves would be the same. The weather being different, more humid or windy does affect the stomatal density. I used clear nail varnish because the stomata get imprinted on it. I use the graticule in the eyepiece because it gives a measurement I could use to measure along the line to see how many stomata were present. To ensure that I counted the number of stomata accurately, I checked several times. Results: Below the table shows the results my group collected. Height (Cm) Light intensity (Lux) Average Light Intensity Stomata present along line of graticule Average number of Stomata present A B C 50 36 37 37 37 6 7 6 6 100 70 69 67 70 8 6 6 7 150 185 184 186 185 6 5 5 5 200 276 275 276 276 7 6 6 7 250 851 850 849 850 8 9 8 8 These are my second set of results: Height (Cm) Light intensity (Lux) Average Light Intensity Stomata present along line of graticule Average number of Stomata present A B C 50 88 87 89 88 6 7 6 6 100 250 251 ...read more.


That as you go into the higher sections of the bush, there will be more stomata present there because those leaves were receiving more light. Evaluation: I think the experiment worked well, because I think I obtained accurate results, my results matched my prediction. I think that the quality of my method and results was quite good. I think that my method was the best way of doing the experiment, it was reliable, and gave accurate results because it was accurate to what I had predicted. I think I had enough correct results to draw a conclusion because me two sets of results were very similar. I have got enough evidence from my results to get a clear picture of how light intensity affects the stomata density. I think that my results were quite accurate and reliable, but for my secondary source of results I don not think they were that reliable. There could be various reasons for why these results were very different to mine. The method they were using could be totally different to mine. Maybe the bush might be a bit thin from where they were taking leaves. Maybe they did not count accurately using the microscope to count the number of stomata along the line of the graticule. To improve the quality of my results, I would do the experiment a couple of more times and compare and see if they are similar or not. Another experiment that could be carried out to extend this work could be to see how temperature also affects the stomata on leaves. ...read more.

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