Codominance Original Scenario-Based Practice

Questions

1. 1.

   Exobiologists studying the nocturnal glimmer-drake discover that scale luminescence is governed by a single autosomal gene with two codominant alleles: $S^R$ directing distinct ruby photophores and $S^A$ directing distinct amber photophores. Crossing a homozygous ruby drake ($S^R S^R$) with a homozygous amber drake ($S^A S^A$) yields $F_1$ progeny that display both ruby and amber photophores side by side. If two of these heterozygous $F_1$ individuals are crossed, which phenotypic distribution will appear among the $F_2$ offspring?

   • A) 1 ruby : 2 ruby-and-amber mosaic : 1 amber
   • B) 3 ruby-and-amber mosaic : 1 amber
   • C) 1 ruby : 2 blended orange : 1 amber
   • D) 3 ruby : 1 amber

Answers and step-by-step solutions appear after you finish the test.