The correct option is
D 150
Let the alleles responsible for the green and yellow coloration of pods be G and g respectively (As green pod colour is dominant over yellow).
Given that out of 300 plants in
F1 generation,
225 plants are green pod producing plants.
Hence the number of yellow pod producing plants
= 300 - 225 = 75.
Hence plants producing green pods : plants producing yellow pods = 225 : 75 = 3 : 1
Since 25% of
F1 offspring are recessive, hence both the parents have a recessive allele. Hence, the possible genotype: _g x _g.
Now, since 75% of the
F1 offspring produce green pods, hence, the genotype of the parent plants is Gg x Gg.
Genotypic ratio in the
F1generation:
GG : Gg : gg = 1 : 2 : 1
⇒ Out of 4 plants, number of plants not true breeding for green pods = 2 (Gg)
⇒ Out of 300 plants, number of plants not true breeding for green pods = 150.
Since, production of green pods is a dominant trait, hence, the number of pea plants not true breeding for the dominant trait = 150.