Question

Predict the genotype and phenotype of the following crossed in pea.
(i) TT × Tt
(ii) tt × TT
(iii) TTrr × ttRR
(iv) TtRr × TtRr

(Capital letters shows dominance)
(i) Give the ratio of phenotypes of these crosses.
(ii) Mention whether the cross is a monohybrid of dihybrid.

Answer 1

The genotype and phenotype will be
(i) TT (tall), Tt (tall)



(ii) Tt (tall)



(iii) TtRr (tall and round seeds)



(iv)



(i) The phenotypic ratio in each case:
(i) 100% as all the plants are tall
(ii) 100% as all the plants are tall
(iii) 100% as all the plants in the F1 progeny will be tall with round seeds
(iv) The phenotypic ratio will be 9 (tall round) : 3 (tall wrinkled) : 3 (dwarf round) : 1 (dwarf wrinkled)

(ii) The cross in (i) and (ii) is monohybrid.
The cross in (iii) and (iv) is dihybrid.