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Does Temperature Effect the Germination of Mustard Seeds?

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Does Temperature Effect the Germination of Mustard Seeds? Biological Problem: "A keen gardener found an old packet of mustard seeds lodged behind some plant pots in the greenhouse and wondered whether the same number of seeds would germinate as from a recently purchased packet. He tried to germinate them but found fewer seeds grew compared to the newly purchased packet. He thought that this might be related to the temperature in the greenhouse". Aim: The aim of my investigation is to see if temperature does actually influence the germination of mustard seeds. Method: * I am going to test the germination of mustard seeds at five different temperatures, these will be; -10?C, 10?C, 20?C, 30?C and 40?C * To do this I will use five separate petri dishes of the same size. * In each dish I will put just enough cotton wool in the dish as to cover the bottom. * On top of the cotton wool, I will place 20 mustard seeds in each petri dish as evenly spaced out as I can. ...read more.


Chi-squared = ?2 = ? (O-E)2/E Key: ? = sum of O = observed results E = expected results I am going to use this test to prove my hypothesis. Diagram: My Results: Temp (?C) -10 10 20 30 40 No. of seeds that have germinated, out of 20. 0 18 14 20 8 0 5 16 19 0 0 10 12 20 6 0 8 13 20 4 Average 0 10.25 13.75 19.75 4.5 Analysis: I have decided to analyse my results gathered, as a result of my investigation, by using a combination of the chi-squared test and line graphs. The chi-squared test (?2 ) is commonly used in biological sciences. It is used to test data that falls into distinct categories, in the form of discrete random variables. It is a measure of how closely the observed results correspond with the expected ones on the basis of the hypothesis; the larger the deviation between the expected and observed results the larger the chi-squared value. For this reason, before calculating the chi-squared values, I must make a null hypothesis, which states chance alone produces, any deviation between the observed and expected results. ...read more.


Table 1 Table of Chi-squared values (based on Fisher) Degrees of freedom Number of classes Chi-Squared Values 1 2 0.016 0.064 0.15 0.46 1.07 1.64 2.71 3.84 5.41 6.64 2 3 0.21 0.45 0.71 1.39 2.41 3.22 4.61 5.99 7.82 9.21 3 4 0.58 1.01 1.42 2.37 3.67 4.64 6.25 7.82 9.84 11.34 4 5 1.61 2.34 3.00 4.35 6.06 7.29 9.24 11.07 13.39 15.09 Probability (P) that chance alone could produce the deviation. 0.9 0.8 0.7 0.5 0.3 0.2 0.1 0.05 0.02 0.01 90% 80% 70% 50% 30% 20% 10% 5% 2% 1% On the Chi-Squared table I need to look at the row I have circled because there are 5 classes in my results table (5 different temperatures) and so 4 degrees of freedom. My Chi-squared result would mean that the probability chance alone could produce a deviation of less that 1% - this is regarded as significant since the probability that the difference between observed and expected results is less than 0.05 (5%). So therefore I need to reject my null hypothesis. In other words temperature does have a significant effect of the germination of mustard seeds. Line Graph Results: Please see graph paper. Analysis of Results: ...read more.

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