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Assess the effect of adjacent pH on the germination of a mustard seed.

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Introduction

Biology Coursework Plan In this project, I am trying to assess the effect of adjacent pH on the germination of a mustard seed. To do this, I am attempting to measure the growth of the germinating seed over a period of 4 days. In order to start the experiment, I will need the following apparatus: - * Petri Dishes * 5cc Syringe * Filter Paper * Mustard Seeds * pH buffers Here is a diagram of the proposed experiment: Method I am going to attempt to calculate the effects of adjacent pH on the germination of a mustard seed by first placing a piece of filter paper in a petri dish. I will then use a syringe to measure 8cc's of buffer solution to place into the petri dish, thereby saturating the filter paper. I will then place 20 seeds onto the paper at regular intervals, uniformly spaced. After replacing the lid of the petri dish, I will move it to a windowsill exposed to light. I will then leave the seeds to experience natural light patterns and temperature changes. I will repeat the experiment, increasing the pH of the buffer solution from 3 to 8 with intervals of for each new set of petri dishes. I will also use pH 9.2 buffer, as it is available and would allow more results to draw my conclusion from. ...read more.

Middle

there are fewer or no large molecules. The buffer molecules diffuse into the seed, as the concentration of buffer outside the seed is greater than inside the seed. The quickest diffusion is experienced at the start of germination, as that is when the concentration gradient (difference) is highest. As the seed continues germination, the swelling of the embryonic tissues ruptures the seed coat, thereby allowing the growing plumule and radical to emerge. The absorbed water activates the enzymes contained within the seed, and allows the hydrolysis (combining with water) of stored food materials (e.g. starch) into soluble products capable of being translocated from the storage tissues to the growing points of the embryo. I think the seeds will grow best in a pH 7 buffer solution, as the seed requires water to grow. Water has a pH of 7 so I predict that the closer to this the buffer pH is - the more it will grow. I think that as the further the pH is from 7, the worse the seeds will grow and germinate. Results By looking at my graph I can see that my prediction is incorrect. I predicted that the further the pH of the buffer solution was from pH 7, the lower the percentage of seeds would germinate. My results show that the optimum pH for growth and germination was pH 4 and not pH 7 as I had predicted. ...read more.

Conclusion

Another factor that may have affected my results is the accuracy of the measurements of the solutions. I kept a consistent accuracy, but (down to small measures) it is possible that the measurements could have varied a little. Again this problem could have been reduced by spending more time on this task, but would have had negligible effects. When looking at measuring accuracy, another obvious flaw is the accuracy of the pH solutions themselves. As I shared the pH solutions with several other groups it is impossible to guarantee that there was absolutely no mixing of the different solutions due to inadequate procedure knowledge by other people. Some pipettes were used to gather the solutions and this will have altered the effects of the mixing even more. I could have avoided this problem by having an exclusive set of solutions for my group, but if done, the effects would be also negligible. The main factor that I think caused the atypical set of results for pH buffer compared to water, are the buffers themselves. As I have stated before, buffers are made using different chemicals. I believe these chemicals have a detrimental effect on germination and are therefore providing different information if pH set water was used instead. To extend this investigation I would try to research the effects of pH on germination. If possible, I would try to find alternative ways of changing the pH of a solution without germination suppressing chemicals. I could also find out about the effects of temperature and density on germination. ...read more.

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