Question

Tired of watering her garden, your instructor is attempting to grow desert plants. One such plant is Indian Paintbrush. A yellow variant has shown up, and we would like to determine if this variant segregates as a single-locus, Mendelian trait. We have taken a pure breeding red plant and crossed it with a pure breeding yellow plant. The resulting F1 plants were self-pollinated with the following results: Red Flowers 350 Yellow Flowers 74 Perform a chi square analysis on this data using the following hypothesis: The mode of inheritance for flower color in Indian Paintbrush is simple Mendelian. Calculate the chi square value without rounding and then round your final answer to three decimal places and put it in the space provided.

Answer 1

The observed number of red flowers plant = 350

The observed number of yellow flower plant = 74

Total number of plants = 424

The both plants have segregated in a 3:1 ratio i.e. the expected number of red flowers= 424*3/4 = 318 and the expected number of yellow flower plant = 424/4 = 106.

Chi square is equal to = (observed-expected)2/ observed

for red flowers Chi square = (350-318)2/ 350 = 1024/350 = 2.92

for yellow flowers chi square = (74-106)2/74 = 1024/74 = 13.837

Total chisquare of the cross = 13.837+2.92 = 16.757

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