Question

A cross was carried out between a pure bred tall pea plant and a pure bred dwarf pea plant and F₁ progeny was obtained.Later, the F₁ progeny was selfed to obtain F₂ progeny. Answer the following questions : 

(i) What is the phenotype of the F₁ progeny and why ? 

(ii) Give the phenotypic ratio of the F₂ progeny. 

(iii) Why is the F₂ progeny different from the F₁ progeny ?

Answer 1

(i) The phenotype of F₁ progeny is Tt because F₁ or hybrid plants were not intermediate between the two alternate forms of a character. They resembled only one parent. In a cross between tall and dwarf of pea plants, the F₁ plants were all tall. 

(ii) The phenotypic ratio of F₂ progeny is 3: 1. 

(iii) F₁ progeny resembled only one parent which is dominant in nature but in F₂ progeny phenotypically three plants are tall and one plant is dwarf. But according to genotype ratio, one plant is pure tall, two are hybrid tall and one plant is a pure dwarf.