In the California poppy, an allele for yellow flowers (C) is
dominant over an allele for white flowers (c).At an independently
assorting locus, an allele for entire petals (F) is dominant over
an allele for fringed petals (f). A plant that is homozygous for
yellow and entire petals is crossed with a plant that is white and
fringed. The F1 progeny were then test crossed and the following
progeny were produced: 54 yellow and entire, 58 yellow and fringed,
53 white and entire, and 10 white and fringed.
Use a chi-square test to compare the observed numbers with those
expected for the cross. Please feel free to use the chi-squared
equation and the chi-squared distribution table (found in the text,
in my lectures and notes, and online in many locations) to answer
the following questions.
What is the p-value for this cross?
A. |
0.01<p<0.05 |
|
B. |
0.05<p<0.1 |
|
C. |
p<0.01 |
|
D. |
0.5<p<0.995 |
|
E. |
0.1<p<0.5 |
The answer is not A. I'm thinking it is B, but I'm not sure
Parents: yellow, entire petals (CC FF) × white, fringed petals (cc ff) F1 (Cc Ff)
For the cross of a heterozygous F1 individual (Cc Ff) with a homozygous recessive
individual (cc ff) we would expect a phenotypic ratio of 1:1:1:1 for the different phenotypic classes.
Phenotype Observed (O) Expected (E) (O - E)2/ E or ( 2)
Yellow, entire 54 43.75 2.40
Yellow, fringed 58 43.75 4.64
White, entire 53 43.75 1.96
White, fringed 10 43.75 26.0
Total 175 175 35
Degrees of freedom = 4 - 1 = 3. The chi-square value is greater than 12.838 for a probability value less than .005, or 0.5% that random chance produced the observed ratio of California poppies.
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