Two autosomal genes control horn color in dragons. Pure-breeding gold-horned dra
ID: 189651 • Letter: T
Question
Two autosomal genes control horn color in dragons. Pure-breeding gold-horned dragons were mated to pure-breeding silver-horned dragons. All of the F1 were gold. The F1 were intermated and the F2 generation consisted of 147 gold, 16 silver and 93 bronze.
Conduct a chi-square test to test the appropriate type of epistasis.
In the chi-square test, what is the expected number of gold-horned dragons? Round to two decimal places.
Conduct a chi-square test to test the appropriate type of epistasis.
In the chi-square test, what is the expected number of silver-horned dragons? Round to two decimal places.
Explanation / Answer
Answer:
As per the information:
Punnett square for this cross can be represented as:
F2 generation consists of 147 gold, 16 silver and 93 bronze (Total = 147 + 16 + 93 = 256)
Dominant epistatsis is suggested by 12:3:1 ratio
Recessive epistatsis is suggested by 9:3:4 ratio.
In this case the ratio is 9:6:1 which is similar to 9:4:3, indicating that epistasis is probably occurring between these two genes.
Chi square analysis can be performed as below:
Degree of freedom = Number of categories - 1 = 3 - 1 = 2
P-value corresponding to chi square value of 0.16 with 2 degree of freedom: P-Value is 0.923116. The result is not significant at p < 0.05. There is sufficient evidence that there is no significant difference in observed frequency as compared to expected frequency based on the epistasis ratio of 9:6:1
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