The offspring

produced by a cross between two given types of plants can be any of the three

genotypes denoted by A, B, C and D. A theoretical model of gene inheritance

suggests that the offspring of types A, B, C and D should be in the ratio 1:1:1:2.

For experimental verification, 150 plants are bred by crossing the two given

types. Their genetic classifications are recorded as below. Do these data

contradict the genetic model? Test at α=0.05.