Question

A cross between a tall pea plant and dwarf pea plant resulted tall progenies in $F_1$ generation, because

• A. Tallness is a recessive trait.
• B. Dwarfness is a dominant trait.
• C. Tallness is a dominant trait.
• D. Neither 'T' or 't' governs stem height.

Answer 1

The correct option is C Tallness is a dominant trait.

A cross between two pure breeding tall (TT) and dwarf (tt) parent plants produce uniform $F_1$ generation of dominant individuals (Tt).

According to the law of dominance, a trait is represented by two contrasting factors of a gene in a heterozygous individual; the allele/factor that can express itself in a heterozygous individual is called as a dominant trait. Another factor whose effect is masked by the presence of a dominant factor is called a recessive factor. The recessive factor, t, is present in $F_1$ hybrids but its expression is masked by the factor for a dominant trait, T.

Thus, all progeny exhibit tallness. If tallness was a recessive trait, it would not have been expressed in heterozygous progeny (Tt). If dwarfism was a dominant trait, the heterozygous progeny (Tt) would have expressed it and was dwarf.

Thus, the correct answer is option C.