In flower beetles, pygmy (py) is recessive to normal size (py^+), and red color
ID: 94809 • Letter: I
Question
In flower beetles, pygmy (py) is recessive to normal size (py^+), and red color (r) is recessive to brown (r^+). A beetle heterozygous for these characteristics was test crossed to a beetle homozygous for pygmy and red. The following are progeny phenotypes from this testcross. Carry out a series of chi-square tests to determine if the two loci are assorting independently. What is the correct chi-square value and how many degree(s) of freedom should be used in its interpretation? A) 112 with one degree of freedom B) 265 with one degrees of freedom C) 16.5 with three degrees of freedom D) 367 with four degree of freedom E) 367 with three degrees of freedomExplanation / Answer
Answer: B). 265 with one degrees of freedom
According to mendel test cross, all progeny should be in equal ratio. Based on this ratio, each phenotype should be 103 in number, which is called as expected value.
Phenotype Observed(O) Expected (E) O-E (O-E)2 (O-E)2/E py+ r+ 180 103 77 5929.00 57.56 py+ r 22 103 -81 6561.00 63.70 py r+ 19 103 -84 7056.00 68.50 py r 191 103 88 7744.00 75.18 412 412 264.95