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Inheritance Patterns for a Lethal Gene

1. A short-tailed mutant of mouse was discovered. Multiple crosses of this mouse to normal mice produced 27 normal, long-tailed mice and 25 short-tailed mice. A series of crosses among short tailed mice were made and 21 short-tailed mice and 11 long-tailed mice were produced. Determine which phenotype is dominant and explain the ratios observed with regards to the genotypes of the parents in each cross

2. In a species of beetle, the wing covers can be either green, blue or turquoise. From an interbreeding, mixed, laboratory stock population, individual virgin beetles were selected and mated in specific controlled crosses to determine the inheritance of wing-cover color. The results were as follows:
Cross Parents Progeny
1 bluexgreen all blue
2 bluexblue 3/4 blue, 1/4 turquoise
3 green x green 3/4 green, 1/4 turquoise
4 blue x turquoise 1/2 blue, 1/2 turquoise
5 blue x blue 3/4 blue; 1/4 green
6 blue x green 1/2 blue,1/2 green
7 blue x green 1/2 blue, 1/4 green, 1/4 turquoise
8 turquoise x turquoise all turquoise
Suggest a hypothesis how these traits are determined which would explain all results. Write the genotypes of the parents and the progeny
Cross Parents Progeny

Solution Summary

This solution explains the concept of lethal genes.