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An Investigation on the factors effecting Germination.

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Introduction

Reg No.8157423 Lisa Atkinson Ref No. 11402/W2 G.C.S.E Biology 01/12/00 An Investigation on the factors effecting Germination Introduction Germination is affected by: water, temperature, oxygen and light in one-way or another. For this investigation I have decided to find out how temperature and oxygen affect the rate of germination, providing there are no other variables i.e. reasonable amount of water and light. For the first part of my experiment I will concentrate on varying the oxygen I predict that the less oxygen in the flask the fewer seeds that will germinate. Without oxygen, respiration cannot take place and as a result the seed cannot get the energy to make new cells. In our atmosphere there is about 20% of oxygen in the air, since the seeds are receive adequate amount of oxygen for respiration. Therefore I think that the normal rate of germination is when there is 20% oxygen. I believe that if all the other elements in our atmosphere i.e. pollution and carbon dioxide was removed that germination might happen quicker. I think the rate of germination will increase and could act as a catalyst, increasing the enzyme activity in the seed and therefore the seed will respire more efficiently. ...read more.

Middle

6. Pyrogallic acid. 7. Sodium hydroxide. 8. Black paper, to cover flask on windowsill. Figure 1: The need for oxygen in germination Oxygen: Is necessary for germination because it is needed for respiration to perform both chemical and mechanical work. It must constantly make new cells and physically drive its roots downward and its shoot upwards. The energy required for this is released as a result of oxidation, which cannot start without a supply of oxygen. Equation: Oxygen + Glucose= Carbon dioxide + Water Results NUMBER OF SEEDS GERMINATED DAY FLASK A FLASK B ONE 0 3 TWO 0 4 THREE 0 13 FOUR 0 17 FIVE 0 19 SIX 0 23 Graph 1 Conclusion The seeds in this experiment followed my predictions. As I predicted, no germination took place in flask A containing Pyrogallic acid and sodium hydroxide. This makes sense since seeds cannot respire without oxygen and this solution removes oxygen and carbon dioxide for the atmosphere. My second prediction was that the sodium hydroxide in Flask B would allow the cress seeds germinate faster as the solution removes carbon dioxide for the atmosphere, this could be because the oxygen will be acting as a catalyst, increasing respiration and therefore giving the seed more energy. ...read more.

Conclusion

I think temperature has quite a distinct effect on the rate of germination and is the main limiting factor. This is because {providing that no factors limit the process of germination} there is a particular range of temperatures in which seeds will germinate, 3 degrees Celsius - 45 degrees Celsius and if it the temperature dose not come in this range the enzymes will be denatured. Therefore looking at my results for the temperature experiment there is a huge difference between the total numbers of seeds that germinate in different areas, proving my theory that temperature is the main limiting factor in the rate of germination. However, it is not sensible to be sure that the predictions made are accurate, without having a wider range of oxygen solutions and temperatures. For example, in the temperature experiment the ranges of temperatures were -7?C (freezer), -3?C (fridge), 12?C ---17?C (window sill), 30�C (airing cupboard) and 50�C (oven). I do not think these are good ranges of temperature because there is a lot of difference in temperatures between the windowsill and the airing cupboard and it is possible that there is a big difference in the rate of germination that cannot be investigated, as the resources are not available. ...read more.

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