Question

Write the phenotypic and genotypic ratios of Mendel’s cross pollination experiments in pea plants with heterozygous yellow seeds (Yy) with the same type i.s. (Yy)?

Answer 1

Genotype : genotype of an individual refers to the sum total of genes inherited from both the parents irrespective of whether they are expressed or not.
Phenotype : phenotype of an individual refers to the expressed or observable structural and functional traits produced by the interaction of genes and environment.

Complete step by step answer:
If the heterozygous yellow seeds Yy is crossed with yellow seeds Yy
Parents : Yy x Yy
Gametes : Y, y , Y ,y
Punnett square :

| Y| y
---|---|---
Y| YY| Yy
y| Yy| yy

Offspring formed : YY( yellow seeds ), Yy ( yellow seeds ), Yy( yellow seeds ) , yy (green seeds)
Phenotypic ratio : 3:1 (from punnett square 3 yellow seeds and 1 green seeds )
Genotypic ratio : 1:2:1 ( from punnett square YY -1 , Yy-2 and yy-1)

Note:
Homozygous organisms: an organism in which both the alleles of a character at the corresponding loci in homologous chromosomes are identical is said to be homozygous or genetically pure for that character. Homozygous individuals breed true for the specific trait i.e. produce offspring with similar genotype and phenotype on inbreeding.
Heterozygous organism: - an organism in which two alleles of a character at the corresponding loci in homologous chromosomes is unlike are said to be heterozygous for that character. Heterozygous individuals do not breed true and are said to be hybrid for that character.