A cross between pure breeding lines of long squash and disk squash produces an F

Question

A cross between pure breeding lines of long squash and disk squash produces an F2 generation with fruits of three shapes sorted as follows The breeder thinks this may represent a 9:6 1 ratio, there are 2 unlinked genes with 2 alleles. The plants with either gene as a recessive homozygote give sphere shaped fruit, the double homozygous recessive gives long shaped fruit, and any plant with at least one copy of each gene as the dominant allele gives disk shaped fruit. Calculate the Chi squared statistic to test this hypothesis. Choose the best answer. The chi-squared value is between -2 and 0 0 and 1 1.01 and 2 2.01 and 4 greater than 4 In a similar experiment to the one discussed in question 12, with white and red roses, but a different population sure, the data gives a chi squared value of 6.12. Check the On squared table and choose the best answer accept at a probability of 0.05 reject at a probability of 0 05 cannot make a choice because you do not know the degrees of freedom cannot make a choice because you do not know the actual sample size cannot make a choice because the null hypothesis is illogical

Explanation / Answer

(12) right choice is c. 1.01 and 2

here we use chi-square test and chi-square=sum((O-E)2/E)=1.476 with (k-1)=3-1=2 df

(13) critical value of chi-square at alpha=0.05 and df=2 is given as

chi-squre(0.05,2)=5.99 and this is less than calculated chi-squre=6.12,

so we fail to accept or reject null hypothesis H0

Observed(O) Exepected(E) (O-E) (O-E)2/E disk 271 9*480/16= 270 1 0.003704 sphere 173 6*480/17= 180 -7 0.272222 long 36 1*480/18= 30 6 1.2 total 480 480 0 1.475926

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