You are working on the genetics of flower color in a plant that breeds true for
ID: 143371 • Letter: Y
Question
You are working on the genetics of flower color in a plant that breeds true for either yellow or red flowers. You begin by crossing yellow and red flowered parents and produce the following F2 phenotypes: 777 red and 219 yellow.
Answer A-C in the photo below. Show all work!
a) What did your F1 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
(a) We can see that approximately 75% of the progeny is Red and 25% is yellow, so the gene for red color is dominant and for that of yellow color is recessive. Genotype for red color is RR or Rr and for yellow is rr.
The above combination gives us 75% red and 25% yellow, so F1 genotypes are Rr and Rr.
(b)
Checking in the chi-squared table with the degree of freedom 1 (n - 1), n is the no. of classes.
4.819 lies between3.841 and 6.635 so the probability is 0.01 showing that the F2 phenotypic ratio is very significantly different from that of expected character.
(c) The critical chi-squared value at p = 0.05 is 3.841 which is less than our calculated value of 4.819, thus we can reject our hypothesis that the ratio is 3: 1 (as seen in the above table) and the phenotypic ratio of F2 generation that came from our F1 plants in part (a) is correct.
If this answer was helpful then please give it a good rating, Thank You.
R r R RR Rr r Rr rrRelated Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.