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Ecological studies of rice (Oryzae Sativa) populations

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Introduction

Practical 13: Ecological studies of rice (Oryzae Sativa) populations Hypothesis There is a significant difference in the lengths of the rice in the two different populations of Oryzae Sativa. Raw and Processed Data Table 1: Uncertainties of apparatus used in the experiment. Apparatus Uncertainties Vernier Calliper ±0.01cm Table 2: Formulae and sample calculations involved in processing data in the experiment. Calculations Formula Sample Calculation Mean ( ) Where, 1. refers to the total number of values. 2. ∑ refers to the addition of all values starting with the first value, denoted by = 1, and ending off with the last value, denoted by . 3. refers to the values in sequence from = 1 to the nth term or last term. Mean length of rice grains from population A: cm Standard Deviation ( ) Where, 1. refers to the total number of values. 2. ∑ refers to the addition of all values starting with the first value, denoted by = 1, and ending off with the last value -denoted by 3. refers to the frequency of that exact term being calculated. 4. refers to the square of the term, denoted by , subtracted by the mean value of the terms, denoted by . Standard Deviation for length of 30 rice grains from population A: T-test ( t ) Where, 1. and are the mean values for the first and second populations respectively. ...read more.

Middle

A t-test can also be used to find out whether the lengths of the rice grains from the two different populations are significantly different. The t value for the data is 18.1, which is considerably higher than that of the critical value of 2.001 given in the probability table for 58 degrees of freedom at a significance level of 95%. This means that there is a significant difference between the two data sets from the two populations; i.e. there is a significant difference in the lengths of the rice grains from the two populations. Hence, we can reject the null hypothesis; that there is no significant difference between the lengths of rice grains from the two populations. We can also conclude that the aforementioned hypothesis is true. The significant difference in the mean length of a rice grain from population A and B is due to polygenic inheritance. It is also the cause of the natural variation in length of the rice grains within the same population. Inheritance of quantitative traits or polygenic inheritance refers to the inheritance of a phenotypic characteristic that varies in degree and can be attributed to the interactions between two or more genes and their environment.[1] The polygenic model makes the following 6 assumptions[2]; 1. Each contributing gene has small and relatively equal effects. ...read more.

Conclusion

This could be done by bringing small sacks of rice and choosing from there, rather than from a small container. 2. A grain grader could also have been used to ensure that all the rice grains used in the experiment were not damaged. This will help to increase the precision of the values as well as the accuracy. Step 3: Measure the length of each of the 30 grains to the nearest 0.005 mm and record the length using a vernier calliper. 1. The vernier calliper is very big compared to the rice grain and hence it is difficult to use it to measure the length of the rice grain, as applying too much pressure may damage the rice grain, affecting the observed value, and also it was very tedious putting the rice grain between the teeth of the vernier calliper. 2. Also, the only characteristic measured in the experiment was grain length. This limited the study to only one phenotype and does not conclusively show whether there is a significant difference in the rice grains from the two populations. 1. A micrometer screw gauge could be used instead. It is more suited for small items like rice and hence will also provide more accurate readings. 2. Other visual characteristics, such as mass, and grain texture could have been compared so as to give further examples of the presence of quantitative distribution as well as making the comparison between the two populations more conclusive. ...read more.

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