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Effect of nitrate concentration on the growth of Duckweeds

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Introduction & Method At the beginning of the experiment, I put on a lab coat to protect myself from any danger that may occur. I made sure that all my equipments were clean and dry before I started, and I also measured the temperature of the room to confirm it was around room temperature. I then made sure that the ice cube tray was clean, I put a little label on one end of the tray to indicate my starting point row of the ice cube tray. I then made a little note to myself that the label indicated the row which will contain the 0.0% x 10-3 concentration of nitrate in the solution, and the rows onwards will contain the concentration of nitrogen in solution in ascending orders which I will use (0.0, 0.4, 0.8, 1.2, 1.6 and 2.4 % x 10-3). I Whilst pouring the solutions into a glass beaker I put on goggles and gloves to protect my eyes and hands from any contacts with the ammonium nitrate solution, as any contact can lead to irritation of the skin and eye. I poured 80-90cm3 of the 1st concentration which contained 0.0% x 10-3 of nitrate into a 100cm3 glass beaker. Next I used a clean syringe to measure out 25cm3 of the solution into the 1st well (near my label). The tray had 3 wells in a row and there were 6 rows, I repeatedly added 25 cm3 of the same ammonium nitrate solution into the remaining two wells of that row, so that I will obtain a result of three replicates with each concentration. Using the replicates will give me a more reliable average result, and it will enable me to use more advanced statistical tests, as the class results will be pooled to generate sufficient data. I pored 80-90cm3 of each solution into the glass beaker, to ensure that there was enough for the other two replicate. ...read more.


The 5 carbon compound RuBP binds to the carbon dioxide, with the help of the enzyme Rubisco to produce another compound, GP. The ATP provides the energy for the synthesis of the synthesis of this compound into sugars such as sucrose. The NADP provides H+ ions for the reduction of organic compound to produce sugar. The Calvin cycle makes carbohydrates, lipids and protein via amino acids. The sugars produced ( mostly sucrose) are transported from the leaves to actively growing regions to provide energy for growth and respiration. The nitrogen is also the component of proteins, which is the polymer of amino acids. Each amino acid contains the carboxyl group, R group and the nitrogen containing amine group. These amino acids link together by peptide bonds, forming a long chain of polypeptides. The chain leads to different structures of proteins. Two kinds of proteins can be made fibrous or globular proteins. The globular proteins that are made are like enzymes such as the Rubisco used in the Calvin cycle. Enzymes in plants are needed to make parts of the plants like chloroplasts and pigments. The membrane of these plant cells contains scattered proteins, which in the root cells allow the uptake of nitrates and other essential nutrients. Proteins are vital components in a plants variety of metabolic pathways and processes. Proteins make up the molecular structure of DNA, RNA and host of other critical metabolic processes required for plant growth. The plant grows using, mitosis as cell division, and therefore copies the previous cells DNA in order to divide and replicate. The cells therefore need to make many new DNA's in each new cell. DNA is made up of 4 nitrogenous bases, adenine, guanine, cytosine and thymine. So the nitrates taken up by the roots are also used to manufacture the DNA, DNA carries the instructions for the cells in the form of codes to make particular proteins. ...read more.


38 16 14 2 0 0 12 20 8 0 0 0 30 12 6 6 4 0 22 18 8 0 0 0 20 36 17 5 2 0 22 24 13 7 4 0 20 36 16 2 1 0 24 18 12 9 0 0 12 14 12 4 2 0 22 8 12 4 8 0 28 22 4 2 0 0 22 14 10 2 0 0 30 30 14 2 0 6 9 24 17 6 5 4 29 7 17 9 6 5 22 24 14 11 6 0 14 33 12 1 0 0 16 30 10 0 0 0 24 28 13 2 0 0 14 24 9 6 5 0 27 24 4 6 7 0 24 22 13 5 0 0 26 24 8 4 0 0 14 18 12 8 0 0 18 24 14 8 4 0 20 26 20 6 0 0 26 28 8 0 0 0 30 26 20 2 0 0 Average 22.23 22 12.7 4.23 1.93 0.57 A table to show the class results and average number of growth of fronds, using all the replicates. The table above shows all the results obtained from the class, and have been pooled together. Each replicate shows the number fronds that were alive after the experiment had ended. These results are going to be used to calculate the t- test, in order to get a more reliable and accurate outcome to prove one of the hypotheses correct or wrong for each of the trends. A table to show my individual results % x 10-3 Concentration of nitrates in solution 0% 0.4% 0.8% 1.2% 1.6% 2% 20 36 17 5 2 0 22 24 13 7 4 0 20 36 16 2 1 0 Average 20.67 32 15.33 4.67 2.33 0 I am using my individual results to plot the graph. ?? ?? ?? ?? Biology A2 level Course work : Effect of nitrate concentration on the growth of Duckweeds ...read more.

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This detailed account just gains 5 stars because the author has a clear grasp of concepts and explains ideas well using A level biological language. There are some, mostly minor, errors.

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Marked by teacher Adam Roberts 25/10/2014

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