Question

Cross of two yellow mice will give _____________ normal mouse.

(a) 1/4

(b) 2/4

(c) 1/3

(d) 2/3

This question was addressed to me by my college professor while I was bunking the class.

I'm obligated to ask this question of Lethal Alleles in section Extension and Deviation from Mendelian Genetic Principles of Cytogenetics

Answer 1

Correct option is (c) 1/3

Explanation: Homozygous condition of the yellow allele will lead to lethality thus the living yellow mouse are heterozygous. Their cross will give 1/4^th of homozygous yellow allele mice which will die changing the proportion of normal mice to 1.3^rd of the living ones.