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Assume tall, yellow, and round are dominant traits over dwarf, green, and wrinkled. In a cross between true-breeding tall, yellow, round plants and true-breeding dwarf, green, wrinkled plants, what would be the expected frequency of tall, yellow, wrinkled plants in the F2 generation?

1/64
3/64
9/64
27/64

1 Answer

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Final answer:

The expected frequency of tall, yellow, wrinkled plants in the F2 generation, given the dominance of tall, yellow, and round traits over dwarf, green, and wrinkled, is 9/64, as calculated by the forked-line method and the concept of independent assortment.

Step-by-step explanation:

The question asks about the expected frequency of tall, yellow, wrinkled plants in the F2 generation when crossing true-breeding tall, yellow, round plants with true-breeding dwarf, green, wrinkled plants, given that tall, yellow, and round traits are dominant. Using the forked-line method, we can calculate the probability of obtaining the desired phenotype by multiplying the probability of each individual trait. The probability for being tall (T) from a cross between two heterozygotes (Tt) is 3/4, as tall is dominant. Now, this is combined with the independent assortment probabilities of seed color and texture. The proportion of yellow (Y) offspring is 3/4 and the proportion of wrinkled (r) offspring is 1/4. Multiplying these gives (3/4) x (3/4) x (1/4), which equals 9/64. Thus, the expected frequency of tall, yellow, wrinkled plants in the F2 generation is 9/64.

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