In: Biology
In garden peas, tall plants are dominant to short plants and smooth seeds are dominant over wrinkled seeds. If two heterozygous tall plants with smooth seeds (TtRr) are crossed, what are the potential genotypes and phenotypes that can be expected in the offspring? What is the genotype of the parents? What are the gametes for each parent? What is the phenotypic ratio? What proportion of the Tall plants with smooth seeds is heterozygous for both traits?
Cross between them TtRr X TtRr
(Tall plants with smooth seed) (Tall plants with smooth seed)
Gametes formed TR, Tr, tR and tr TR, Tr, tR and tr
Next generation
Male/ Female | TR | Tr | tR | tr |
TR | TTRR (Tall plants with smooth seed) | TTRr (Tall plants with smooth seed) | TtRR (Tall plants with smooth seed) | TtRr (Tall plants with smooth seed) |
Tr | TTRr (Tall plants with smooth seed) | TTrr(Tall plants with wrinkled seed) | TtRr (Tall plants with smooth seed) | Ttrr (Tall plants with wrinkled seed) |
tR | TtRR (Tall plants with smooth seed) | TtRr (Tall plants with smooth seed) | ttRR(Short plants with smooth seed) | ttRr(Short plants with smooth seed) |
tr | TtRr (Tall plants with smooth seed) | Ttrr(Tall plants with wrinkled seed) | ttRr(Short plants with smooth seed) | ttrr(Short plants with wrinkled seed) |
Genotypes of offsprings - 1 TTRR : 2TTRr: 2 TtRR: 4 TtRr: 1TTrr: 2 Ttrr: 1 ttRR: 2 ttRr: 1 ttrr.
Phenotypes of offsprings : TTRR, TTRr, TtRR and TtRr - 9 (Tall plants with smooth seed).
TTrr and Ttrr - 3 (Tall plants with wrinkled seed).
ttRR and ttRr - 3 (Short plants with smooth seed).
ttrr - 1 (Short plants with wrinkled seed)
The genotype of the parents - TtRr.
The gametes for each parent - TR, Tr, tR and tr .
The phenotypic ratio - 9:3:3:1.
Proportion of the Tall plants with smooth seeds - 9/16 = 0.5625 = 56.25%.