In case of seed colour in Pisum sativum, yellow colour is dominant over green colour. If the F1 generation has 75% offspring producing yellow coloured seeds and 25% offspring producing green coloured seeds, then, which of the following statements is true about the genotype of the parents?
In case of seed colour in Pisum sativum, yellow colour is dominant over green colour. If the F1 generation has 75% offspring producing yellow coloured seeds and 25% offspring producing green coloured seeds, then, which of the following statements is true about the genotype of the parents?
The correct option is B Both the parents are heterozygous
Let us assume that the allele responsible for imparting yellow colour to seeds is Y and the allele responsible for imparting green colour to seeds is y.
It is given in the question that 75% offspring produce yellow coloured seeds and 25% offspring produce green coloured seeds in the F1 generation. Hence the ratio is 3 : 1 (yellow : green)
This ratio is possible when both the parents are heterozygous for seed colour.
Hence, genotype of both the parents is Yy.
In other words, both the parents are heterozygous.
If both the parents are homozygous (YY and yy), then all the offspring obtained will produce yellow coloured seeds.
If one of the parents is heterozygous (Yy) and the other parent is homozygous dominant (YY), then all the offspring obtained will produce yellow coloured seeds.
If one of the parents is heterozygous (Yy) and the other parent is homozygous recessive (yy), then the offspring producing yellow and green coloured seeds will be obtained in the ratio of 1 : 1.
Hence, 75% offspring produce yellow coloured seeds and 25% offspring produce green coloured seeds in the F1 generation when both the parents are heterozygous (Yy).
Let us assume that the allele responsible for imparting yellow colour to seeds is Y and the allele responsible for imparting green colour to seeds is y.
It is given in the question that 75% offspring produce yellow coloured seeds and 25% offspring produce green coloured seeds in the F1 generation. Hence the ratio is 3 : 1 (yellow : green)
This ratio is possible when both the parents are heterozygous for seed colour.
Hence, genotype of both the parents is Yy.
In other words, both the parents are heterozygous.
If both the parents are homozygous (YY and yy), then all the offspring obtained will produce yellow coloured seeds.
If one of the parents is heterozygous (Yy) and the other parent is homozygous dominant (YY), then all the offspring obtained will produce yellow coloured seeds.
If one of the parents is heterozygous (Yy) and the other parent is homozygous recessive (yy), then the offspring producing yellow and green coloured seeds will be obtained in the ratio of 1 : 1.
Hence, 75% offspring produce yellow coloured seeds and 25% offspring produce green coloured seeds in the F1 generation when both the parents are heterozygous (Yy).
