A variety of pea plants called Blue Persian produces a tall plant with blue seed

Question

A variety of pea plants called Blue Persian produces a tall plant with blue seeds. A second variety of pea plant called Spanish dwarf produces a short plant with white seed. The two varieties are crossed, and the resulting seeds are collected. All of the seeds are white; and when planted they produce all tall plans. The tall F1 plants are allowed to self fertilize. The results for seed color and plant stature in the F2 generation are as follows: Blue seed, Tall plant:97; White seed, tall plant: 270; Blue seed, short plant: 33; white seed, short plant: 100.

Which phenotypes are dominant, and which are recessive? Why?

What is the expected distribution of phenotypes in the F2 generation?

State the hypothesis being tested in the experiment.

Examine the data in the table by the chi-square test, and determine whether they conform to expectations of the hypothesis.

Explanation / Answer

The resulting progeny represents the 9:3:3:1 ratio of a mendalian dihybrid cross. This ratio comes from a cross between two heterozygous parents.

So, according to this data, we can conclude that White and tall phenotypes are dominant, and blue and dwarf phenotypes are recessive.

The expected distribution of phenotypes in the F2 generation is 9:3:3:1

The hypothesis is: If the parents are heterozygous the given traits, then the resulting cross would produce offsprings in the 9:3:3:1 ratio.

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