4. You are working red flowers. Y F2 phenotypes: 777 red and 219 yellow. on the

Question

4. You are working red flowers. Y F2 phenotypes: 777 red and 219 yellow. on the genetics of flower color in a plant that breeds true for either yellow or ou begin by crossing yellow and red flowered parents and produce the following a) What did your F, plants look like and what were their genotypes? (1pt) b) Use a chi-square test to address the following question: is the F2 phenotypic ratio significantly different from that expected for a monogenic character that is inherited according to Mendelian principles? Remember that you'll need to look at Fig. 3-11 to get a semi-accurate p-value. (1pt) c) State (in one or two complete sentences) whether or not your results were significant and what that means in relation to the question you were addressing. (0.5pt)

Explanation / Answer

Please find the answers below:

Answer 1: According to the information, the cross between these two plants gives a ratio of red to yellow as 777 to 219. According to Mendelian pattern of inheritance, this ratio should be ideally 3:1. The calculated ratio is 3.55:1 which deviates from ideal.

Answer 2: The Chi-square test can be found as below:
Total results: 219+777 = 996.

Expected red results : 996/3/3=747

Observed red results: 777

Chi square = (Observed - Expected)2 / Expected

Chi square = (777-747)2/747 or (30)2/747 = 900/747 or 1.21

The standard reference table states that the value of p for this value of Chi square is nearly 0.271

Answer 3: Since this calculated value of p is much higher than the acceptable value, i.e. 0.05, it demonstrates that the data is not significant statistically.

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