Cross of true-breeding parents:
For a dihybrid cross: 9:3:3:1 phenotypic ratio (9 tall+violet : 3 tall+white : 3 dwarf+violet : 1 dwarf+white)
For a monohybrid cross: 3:1 phenotypic ratio (3 tall or violet : 1 dwarf or white)
Total number of offsprings = 80 + 36 + 39 + 5 = 160 flowers
Expected tall+violet flowers = = 90 flowers
Expected tall+white flowers = = 30 flowers
Expected dwarf+violet flowers = = 30 flowers
Expected dwarf+white flowers = = 10 flowers
Table of chi-square values
Imagine that you attempted to recreate Mendel's work with garden peas. You began by crossing true breeding violet-flowered, tall plants with white flowered dwarf plants. After self-crossing the F1 generation, you obtain the following phenotypes in the F2 generation:
80 tall, violet flowers
36 tall, white flowers
39 dwarf, violet flowers
5 dwarf, white flowers
How many tall plants with violet flowers were expected?
How many tall plants with white flowers were expected?
How many dwarf plants with violet flowers were expected?
How many dwarf plants with white flowers were expected?
Use a chi-square analysis to test the hypothesis that the F2 data for stem length (tall:dwarf) is consistent with Mendel's law of segregation. Calculate the chi square value.
Use a chi-square analysis to test the hypothesis that the F2 data for stem length (tall:dwarf) and flower color (violet:white) is consistent with Mendel's law of independent assortment. Calculate the chi square value.
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