Two true-breeding lines of beans are crossed. One line is tall with green pods,
ID: 96045 • Letter: T
Question
Two true-breeding lines of beans are crossed. One line is tall with green pods, the other line is short with yellow pods. The F1 are medium height with yellow pods and are allowed to self-fertilize. The F2 progeny are listed below. a) How is plant height inherited? Calculate the ratios (to 2 decimal places) to support your answer. b) How is pod color inherited? Calculate the ratios (to 2 decimal places) to support your answer. F1 generation: All offspring are medium height with yellow pods F2 generation: 299 tall with yellow pods 101 tall with green pods 610 medium height with yellow pods 201 medium height with green pods 296 short with yellow pods 97 short with green pods Total: 1604Explanation / Answer
a) number of tall plants = 299 +101 = 400
number of medium height plants = 610 + 201 = 811
number of short height plants = 296 + 97 = 393
Ratios -
phenotypic ratio is 0.24 : 0.50 : 0.24 , i.e. ~ 1 :2 : 1
Therefore the plant height is incompletely dominated by gene for tall height. In heterozygous conditions plants are of medium height and in recessive condition plants are of short height.
b) number of plants with yellow pods = 299 + 610 + 296 = 1205
number of plants with green pods = 101 + 201 + 97 = 399
Ratios -
phenotypic ratio = 0.75 : 0.25 , i.e. = 3 : 1
Therefore pod color is dominantly inherited by yellow color gene.
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