Question

A recessive allele is expressed in

• A. heterozygous condition only
• B. homozygous condition only
• C. $F_3$ generation
• D. both homozygous and heterozygous conditions

Answer 1

Answer: (B)

homozygous condition only

Answer 2

The factor of an allelic or allelomorphic pair which is unable to express its effect in the presence of its contrasting factor in a heterozygote is called recessive factor or allele, e.g., the allele $'t'$ in hybrid tall pea plant $Tt$. The effect of recessive factor becomes known only when it is present in the pure or homozygous state, e.g., $tt$ in dwarf pea plant.