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Lemna coursework

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Emma Lazarus - 10Y1 - 10/PLR Lemna coursework Introduction Lemna are small water plants found in ponds. Typical of plants, they reproduce asexually. When they reproduce they form a bud on the edge of a leaf, which, when big enough, will eventually separate from the mother leaf and can then reproduce itself. Sometimes lemna plants can have up to 3 or 4 buds. Exactly the same as plants in soil, they use the sun's energy for photosynthesis, and water, but they have to take all their nutrition to grow and reproduce from the water. I am going to look at how lemna are affected by deficiencies in nitrogen, iron and magnesium. Question How do lemna plants cope in environments lacking certain mineral salts - nitrogen, iron and magnesium? Photosynthesis equation sunlight carbon dioxide + water -->-->-->-->--> glucose + oxygen chlorophyll sunlight 6CO2 + 6H2O -->-->-->-->--> C6H12O6 + 6O2 chlorophyll Prediction I predict that the lemna in the complete culture solution will thrive, growing and reproducing at a high rate. This therefore means that by the end of our experiment these lemna will be the greatest in number. I also think that they will remain green and healthy, and should have no abnormalities or deaths. This is because the lemna have all the mineral salts that they could ever possibly need in order to grow and reproduce. To photosynthesise, plants need carbon dioxide and water as basic raw materials. However, they also need many different mineral salts, which help the plant to grow, make chlorophyll and photosynthesise among other things. ...read more.


yellowish, lots dead, lots of sediment at bottom Graphs Conclusion I conclude that the lemna that were the most successful were the ones in the complete culture solution. This is because they had all the mineral salts that they could ever ask for, meaning they were able to make chlorophyll, proteins, enzymes, and all the things that are vital for a plant's survival. By the fifth week, there were 45 lemna plants, so they had been growing and reproducing at a high rate. As you can see from the line graph, the number continues to increase reasonably steadily. This was as expected because I knew that these lemna would have everything they needed in the way of minerals, and there would be nothing stopping them making steady or even rapid progress, which was exactly what we saw. Also, over the weeks the plants remained green and healthy. To photosynthesise, plants need carbon dioxide and water as the raw materials, but they also need mineral salts essential for making different substances that the plant needs to grow, reproduce, respire and all the other processes a plant has to do to stay alive. Plants need many different mineral salts, and a complete culture solution contains all of them in the right quantities, as water plants get their nutrients from the water rather than the soil. The lemna that were the least successful were those in the solution with no nitrogen ions in it. They only reached 28 in number. They were also the least healthy of all the lemna. ...read more.


It would have been more suitable to use larger plants where you can see the symptoms more easily. To make our results more reliable, we could perhaps have checked the lemna daily. This would give us a more accurate and reliable line graph, as the data would be closer together. As it is we are only able to estimate what the values in between each week were. We had 7 anomalous results. This sounds like a lot, but because we repeated our result 5 times it does not matter a great deal. The reason for these anomalies is quite simple. It was because living things do not photosynthesise at a steady rate. They have periods of photosynthesising well, and periods of photosynthesising badly. This results in us not achieving the results we might have expected. Another thing that might have happened is that the plants had a lack of carbon dioxide. We could solve this by adding sodium hydrogen carbonate to the solution, to provide the plants with extra carbon dioxide. Of course, the anomalies could have been due to our bad judgement of whether or not the lemna had a bud on it when we chose them, or perhaps the health of them was not too good. For further work to our experiment, we could investigate further mineral deficiencies. This would involve using a wider range of variables. For example we could use a solution containing no phosphorus ions, or one with no calcium ions. We could even put some lemna in some distilled water, which does not contain any minerals, and observe how they coped. We would count how many there were over several weeks and also make other observations as we did in this experiment. ...read more.

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