Question

A dinybrid cross would be a cross between a plant with and a plant with purple flowers, wrinkled seeds X white flowers, smooth seeds purple flowers, smooth seeds X white flowers, smooth seeds purple flowers, wrinkled seeds X white flowers, wrinkled seeds purple flowers, tall plants X white flowers, smooth seeds purple flowers, wrinkled seeds X purple flowers, smooth seeds
Please explain

Answer 1

The correct statement is as follows:

A dihybrid cross would be a cross between a plant with a) purple flowers, wrinkled seeds X white flowers, smooth seeds

A di hybrid cross by definition refers to a genetic cross between two strains having two different observable phenotypes for a given trait.

In terms of genotype or genes expressing the traits, usually the gene for a given trait would have two alleles, one dominant and one recessive (relative to each other) such that in combination we obtain two phenotypes; one recessive and one dominant.

In the above example, we can see that the two traits are Flower colour(the two phenotypes are purple that is dominant and white that is recessive) and seed coat texture (wrinkled that is dominant and smooth that is recessive).

in all other options provided, either of the two traits in the lines to be crossed are the same i.e. both lines have the same seed coat phenotype or flower colour or as in d) there is an uncommon trait of plant height i.e. tall vs short, which is not being compared in the second line that is being crossed.

Hence the only correct option remains A) where the first line has purple flower colour phenotype and the second line has white and similarly for seed coat the first line has wrinkled seeds and the second line has smooth seeds.