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The practical that has been carried out shows how many pigments there are present in spinach.

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Introduction

Introduction The practical that has been carried out shows how many pigments there are present in spinach. Plan For photosynthesis to occur plants require light energy, which is received from the sun. The photosynthetic pigment chlorophyll is the means of capturing this light energy. There is a simple test that can be done to show that chlorophyll is needed for photosynthesis. Consider the leaves of a variegated plant, they have certain areas containing chlorophyll and other areas containing no chlorophyll. These regions where no chlorophyll is present are usually creamy in colour. If a de-starched variegated is exposed to light and one of the leaves is tested for the presence of starch, the solution applied to the leaf changes from red to blue-black colour. This change in colour only occurs in the areas of the leaf which were green. This green colouring in plants is a result of five closely related pigments. These pigments are:- Chlorophyll a Chlorophyll b Carotene Xanthophyll Phaeophytin Chlorophyll a is found in all photosynthesizing plants and it is most abundant out of the five pigments. ...read more.

Middle

Pin 13. Boiling tube with cork 14. Test tube rack Method The first thing to do is to take 5 large leaves from the spinach. Dip the leaves into boiling water for 2 minutes. After taking the leaves out of the boiling water chop the lamina of each leaf into small pieces. Add a minimum volume of acetone to the pieces of leaves to form a very concentrated extract. Grind the leaves in the acetone using a small pestle and mortar. Filter the extract with the filter paper and collect the filtrate in the conical flask. To separate the pigment from the extract cut a piece of chromatography paper. The paper should be cut to a sufficient enough length that the paper reaches to the bottom of the boiling tube. The width of the paper should be cut so that the paper does not touch the edges of the boiling tube. Draw a pencil line 3cm from the one of the paper and fold the other end through 90. Then using the head of a pin as a dropper place a drop of the leaf solution at the centre of the pencil line. ...read more.

Conclusion

My hypothesis proved correct as chlorophyll b separated first and was then followed by chlorophyll a. I feel that my results could have been more accurate. This because the leaves used in the experiment were not soaked in boiling water. Another factor that made my results that made my results less accurate was the fact that I used glass fibre instead of filter paper to filter the extract. Other alterations made in the methodology were that propanone was used instead of acetone. Also, instead of using the head of a pin to build up a concentrated area on the chromatography paper, I used a piece of capillary tubing. The capillary tubing was a better piece of equipment to use than the pin as helped build up a finer concentrated area. Since there are only two pigments present in spinach the maximum amount of light cannot be absorbed. This means that the light independent stage of photosynthesis not as many electrons in the chlorophyll are being excited slowing down the whole process. As there were only found to be two pigments my final conclusion is that photosynthesis does not occur at a fast rate in spinach. ...read more.

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