The back cross can distinguish heterozygotes from homozygotes

the-back-cross-can-distinguish-heterozygotes-from-homozygotes

The back cross can distinguish heterozygotes from homozygotes as they give _________ phenotypic ratio respectively.

A. 1:1 dominant: recessive ; all recessive

B. All dominant; all dominant

C. 1:1 recessive; dominant; all dominant

D. All dominant; 1:1 recessive: dominant

I had been asked this question in an interview.

The origin of the question is Monohybrid Cross in portion Mendelian Genetics of Cytogenetics

Correct option is C. 1:1 recessive; dominant; all dominant

The explanation is: Test cross with a double recessive parent and a homozygous dominant will give all heterozygotes, which will express dominant trait. On the other hand heterozygotes will give 1:1 heterozygote: homozygote which will express dominant: recessive.