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An Investigation to determine the effect of varying temperature on mustard seed germination over a one week period.

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Introduction

An Investigation to determine the effect of varying temperature on mustard seed germination over a one week period. In a flowering plant, a seed is made up of an embryo and a food store, which is enclosed within an impermeable seed coat (called testa). A micropyle is the only gap in the seed coat. If the environmental conditions are right the seed will grow into a new young plant. At the start of germination water enters through the micropyle and activates enzymes to convert insoluble stores to soluble food and also makes tissues swell so that the testa (seed coat) is spilt open. Next water and oxygen enter through the gaps in the testa. Oxygen and glucose enable aerobic respiration in the seed, which releases energy to enable growth. The embryo is now able to grow as it receives raw materials and energy. It begins with a growth of the radicle that anchors the seeding to the soil and starts to absorb water and mineral ions. Then the plumule (young shoot) emerges and grows up. The radicle and plumule continue to grow in to a young plant. For a seed to germinate it needs a supply of water, oxygen for aerobic respiration and a temperature suitable for the enzymes involved in germination in some seeds light is needed. ...read more.

Middle

= 20.5 + 8.89 + 72.3 + 61.48 + 18.55 + 20.5 = 202.22 From the graph the germination of seeds greatly increased from 0?c to 20?c, with no seeds germinating at 0�c and 20 seeds germinating at 20�c. At the temperature of 20?c and 30�c the number of seeds that germinated is similar but not the same. After 30�c the germination of seeds greatly decreased until it reached 50�c where no seed germinated. From the graph you could suggest an optimum temperature for the biggest yield of mustard seeds; this would be between 20�c and 30�c. At the temperature 0?c no seeds germinated. This is because there is not heat energy so enzymes remain inactive and will become active once again when a higher temperature is restored. Also because there is no heat energy then there is little movement so the chance of random collisions between the substrate and active site of the enzyme are low. This would mean that there would be few or no enzyme-substrate complexes. This would cause no activation of enzymes so therefore there would be no germination. As temperature rose from 0�c to 20�c there was an increase germination rate. The increased temperature increases the rate of enzyme reaction. This increase in the heat energy will increase the kinetic energy. Both enzyme molecules and substrate molecules move faster and increase the number of random collisions between the substrate and the active site of the enzyme. ...read more.

Conclusion

You would expect all the seeds to germinate but not all of them did. This may be because there were sterile seeds in the packet of seeds in this investigation. In any investigation there may be errors which have occurred that we could improve on if we were doing this investigation again. The possible errors that could have occurred would have been that the cotton wool wasn't uniformly wet this would mean that some of the seeds would get more water than the rest and also not creating the experiment a fair one. Improvements to this investigation that could be made would be trying the seeds in different temperatures. For example start from 0�c and graduate up in 5�c intervals. There would be no need to do any temperatures below 0�c because in this investigation no seeds germinated at this temperature. This is also true for trying any temperatures above 50�c. To further investigate what affects germination in seeds there are many investigations that could be carried out. For example does the amount of water affect the rate of germination? Does the amount of oxygen affect germination within a seed? Is germination dependent the intensity of light? Does the amount of space that the seed has affect its rate of growth? Different seeds may have different optimum temperatures because of different conditions that they are used to. Another investigation that could be explored could be to find the optimum germination temperatures are of different seeds and compare them and the conditions you would normally find them in. ...read more.

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