2. Mendel's Laws of Inheritance

In cattle, coats may be solid white, solid black, or black-and-white spotted. When true-breeding solid whites are mated with true-breeding solid blacks, the generation consists of all solid white individuals. After many matings, the following ratio was observed in the generation:

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Explain the mode of inheritance governing coat color by determining how many gene pairs are involved and which genotypes yield which phenotypes. Is it possible to isolate a true-breeding strain of black-and-white spotted cattle? If so, what genotype would they have? If not, explain why not.

Students taking a genetics exam were expected to answer the following question by converting data to a “meaningful ratio” and then solving the problem. The instructor assumed that the final ratio would reflect two gene pairs, and most correct answers did. Here is the exam question:

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Convert the data to a meaningful ratio that allows you to explain the inheritance of color. Determine the number of genes involved and the genotypes that yield each phenotype.”

a.Solve the problem for two gene pairs. What is the final ratio?

Students taking a genetics exam were expected to answer the following question by converting data to a “meaningful ratio” and then solving the problem. The instructor assumed that the final ratio would reflect two gene pairs, and most correct answers did. Here is the exam question:

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Convert the data to a meaningful ratio that allows you to explain the inheritance of color. Determine the number of genes involved and the genotypes that yield each phenotype.”

b. A number of students failed to reduce the ratio for two gene pairs as described above and solved the problem using three gene pairs. When examined carefully, their solution was deemed a valid response by the instructor. Solve the problem using three gene pairs.

Students taking a genetics exam were expected to answer the following question by converting data to a “meaningful ratio” and then solving the problem. The instructor assumed that the final ratio would reflect two gene pairs, and most correct answers did. Here is the exam question:

“Flowers may be white, orange, or brown. When plants with white flowers are crossed with plants with brown flowers, all the flowers are white. For flowers, the following data were obtained:

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Convert the data to a meaningful ratio that allows you to explain the inheritance of color. Determine the number of genes involved and the genotypes that yield each phenotype.”

b. A number of students failed to reduce the ratio for two gene pairs as described above and solved the problem using three gene pairs. When examined carefully, their solution was deemed a valid response by the instructor. Solve the problem using three gene pairs.