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Allelic segregation and frequency

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1. A short-tailed mutant of mouse was discovered. Multiple crosses of this mouse to normal mice produced 27 normal, long-talied 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. You hypothesized that snapdragon flower color is controlled in an incomplete dominant manner. You created an F1 population by crossing red and white parents and selfed the F1 plants and obtained the following ratio: 31 red, 66 pink, and 27 white flowered plants. Suggest a hypothesis for this ratio and perform a Chi-square test to see if the results fit the hypothesis.

3. Two corn homozygous, white-seeded corn lines were crossed and all progeny were red-seeded. These red-seeded F1 progeny were selfed, and the population segregated 9 red-seeded:7 white-seeded. Explain these results by determining the number of genes controlling seed coat colors and giving the genotypes of the parents.

4. What type of cross would produce the following genetic ratios? Write the genotypes that would lead to these ratios.
? 3:1
? 1:1
? 1:2:1
? 9:3:3:1
? 1:1:1:1
? 13:3

5. 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, 1/2 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 gree, 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

Cross Parents Progeny

6 (extra). In the movie "Made in America" character played by Whoopi Goldberg has blood groupA, her son group O and her daughter is AB group. Her daughter, a medical students, thinks she is '"genetically impossible" and suspects that she is adopted or has a different father. Is she right? Explain.

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Solution Summary

Answers with explanation and calculation for genotype and phenotype calculations for several problems involving mono and di-hybrid crosses.

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