Question

In a cross between pure tall pea plants (TT) and pure dwarf pea plants (tt) the offsprings of F$_1$ generation were all tall. When F$_1$ generation was self-crossed, the gene combinations of the offsprings of F$_2$ generation will be :

• A. TT : Tt : tt
• B. TT : tt
• C. Tt : tt
• D. TT : Tt

Hint:

In a monohybrid cross, the genotype ratio in F$_2$ is always 1:2:1.

Answer 1

The Correct Option is A

When a pure tall plant (TT) is crossed with a pure dwarf plant (tt), all F$_1$ plants have the genotype Tt and are tall (because tallness is dominant). When the F$_1$ plants (Tt) are self-crossed: \[ \text{Parent: } Tt \times Tt \] The Punnett square shows: \[ \begin{array}{c|cc} & T & t \\ \hline T & TT & Tt \\ t & Tt & tt \\ \end{array} \] So, the genotypes in F$_2$ generation are: - 1 TT : 2 Tt : 1 tt Therefore, the gene combinations will be TT, Tt, and tt.