Question

A breeding experiment was conducted in pea plant wherein the tallness of a plant was being studied. A pure tall plant was first taken as a male plant and then as the female plant in the second cross. The other plant in both the cases was a pure dwarf plant. The purpose of this experiment was primarily to find out

• A. which allele is able to express itself in the heterozygous state
• B. the role of parental sex on a given inheritance pattern
• C. which was the dominant trait and which was the recessive trait
• D. the reason of appearance of recessive character in F${}_2$ generation

Answer 1

The correct option is B the role of parental sex on a given inheritance pattern

The experiment conducted above is called the reciprocal cross. Reciprocal cross is a breeding experiment performed to ascertain the role of parental sex on a given inheritance pattern. All parent organisms must be true breeding to properly carry out such an experiment. It is done to find out whether there is any change in the traits of offspring if the traits of the parents are reversed.

Mendel performed a reciprocal cross to find out whether the sex of the parent influenced a trait of a character.

In the heterozygous condition, both the alleles present are dissimilar. In such a condition, the allele that is able to express itself is called the dominant allele. Hence dominant allele requires only one copy for its expression. It can represent itself in the presence of its counterpart. The recessive allele, on the other hand, requires both recessive copies to be able to express itself.

Reciprocal crossing of tall and dwarf pea plants specifically doesn’t play any role in determining the dominant and recessive traits.

Similarly, a reciprocal cross specifically cannot tell us about the reason of the appearance of the recessive trait in the $F_2$ generation.