In peas, the yellow color of the seeds is dominant in relation to the green one. 158 seeds in F1 and 3256 in F2 were obtained from the crossing of homozygous yellow-seed and green-seed plants A) How many F1 seeds are homozygous? B) How many different genotypes do F1 seeds have? C) How many different phenotypes have seeds F2? D) How many F2 seeds can be homozygous? E) How many green seeds can F2 be?
Let’s designate the gene that causes yellow coloration of pea seeds as C, then the gene that causes their green coloration will be designated as c.
Peas with yellow seeds are homozygous by condition – CC. It produces C.
Peas with yellow seeds – cc, because for the realization of yellow seeds in the phenotype of peas, homozygosity of its genotype is required. Such peas produce one type of germ cells – p.
All 158 plants in F1 have the Cc genotype and produce yellow seeds. They produce germ cells of two types – c and C.
When such hybrids are crossed among themselves, the F2 offspring include the following options:
homozygous peas with green seeds (cc) – 25%;
homozygous peas with yellow seeds (CC) – 25%;
heterozygous peas with yellow seeds (Cc) – 50%.
A) 0 homozygous seeds in f1;
B) 1 genotype (Cc);
C) 2 phenotypes in F2;
D) 50% (CC + cc), or 3256 * 0.5 = 1628 seeds;
D) 25% (cc), or 3256 * 0.25 = 814 seeds.