In case of rats the homozygous yellow allele is lethal. If you cross two yellow pats, what will be the ratio of white and yellow rats?

In case of rats the homozygous yellow allele is lethal. If you cross two yellow pats, what will be the ratio of white and yellow rats? Correct Answer 2:1

Homozygous yellow rat YY is lethal, so the parent must be heterozygous Yy. Now, the living progenies will be Yy and yy i.e. yellow and white in the ratio 2:1 and YY will be lethal.
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