A paired cross in which the male and female traits are swapped between the two crosses is a:

1. Mendel needed to rule out any effect of which parent contributed which trait. 2. So he ran each cross twice, with the parental roles exchanged. 3. This is called a reciprocal cross, a paired cross in which the respective traits of the male and female in one cross become the respective traits of the female and male in the other cross. 4. Getting the same result both ways showed the outcome did not depend on the parent's sex. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 12 'Mendel's Experiments and Heredity', sections 12.1-12.3_