help please 7. You are investigating the inheritance of petal shape in tulips. T

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help please

7. You are investigating the inheritance of petal shape in tulips. There are two types of flowers, those with entire (smooth) edges and those with feathered edges. You carry out the following three crosses: Cross Parent Phenotypes Progeny Phenotypes Smooth x Smooth 2 Smooth x Feathered Smooth x Feathered 40 Smooth, 7 Feathered 20 Smooth, 35 Feathered 200 Smooth, 195 Feathered 1 3 On the basis of these results, what is the most likely mode of inheritance of the smooth edge phenotype? A. B. Give the most likely genotypes of the parent in each cross. Use a chi-square test to evaluate the fit of the observed numbers of progeny to the number of expected on the basis of your proposed genotypes for cross number 1. C.

Explanation / Answer

This question is the direct case of dihybrid cross.

According to the question,results shows that Smooth edge loci is dominant over feathered edge.

If smooth edge denoted with (SS) and feathered edge is denoted as (ff)

Then possible genotype would be SSff which gives smooth edge flower.

So when smooth X smooth in (a)

SSff X SSff dihybrid cross

Gamete Sf

Punnet square.

S. f

S. SS. Sf

f. Sf. ff

75% smooth and 25% feathered

In (b) and (c) crossover between gametes

I.e. Sf X ff

Gives 50% smooth and 50% feathered edge.

A) complete dominance.

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