In the F₂ generation of a homozygous round (AA) × homozygous wrinkled (aa) cross in peas, two seeds are chosen at random. What is the probability that one is AA and the other aa? A)(1/4)² B)(3/4)(1/4) C)2(3/4)(1/4) D)(3/4)²

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Quizplus · Accepted Answer

The first generation (F1) from a cross between homozygous round (AA) and homozygous wrinkled (aa) peas will all be heterozygous (Aa), producing gametes that are either A or a. When these F1 individuals self-pollinate, the offspring (F2) will have a genotype ratio of 1AA:2Aa:1aa, or a phenotype ratio of 3 round (AA or Aa) to 1 wrinkled (aa). The probability of selecting one AA and one aa seed is calculated by considering the combinations of picking AA first then aa, or aa first then AA. The probability of picking an AA seed is 1/4, and the probability of picking an aa seed is also 1/4. Since there are two ways this can happen (AA then aa, or aa then AA), we multiply the probability of one event by 2. The probability of picking a round seed (either AA or Aa) is 3/4. Thus, the correct calculation is 2 times the probability of picking an AA seed (1/4) times the probability of picking an aa seed (1/4) after picking a round seed, which is 2(3/4)(1/4).

In the F2 Generation of a Homozygous Round (AA) ×

In the F₂ Generation of a Homozygous Round (AA) ×