Final answer:
The combined probability of two heterozygous cells (Yy) undergoing meiosis and producing homozygous recessive offspring (yy) is calculated by using the product rule of probability, which yields 1/256.
Step-by-step explanation:
The probability of both cells undergoing meiosis to produce homozygous recessive offspring (yy) for gene Q. In a heterozygous (Yy) cell, there are two alleles for gene Q: one dominant (Y) and one recessive (y). During gamete formation in meiosis, there is a 50 percent chance that a gamete will receive the recessive allele. To get a yy offspring, the y allele from one parent must combine with a y allele from the other parent. The product rule of probability is applied to calculate this. Each cell, being identical and heterozygous, has a 1 in 4 chance of producing a gamete with the recessive allele. Therefore, the combined probability for two cells is (1/4) * (1/4), which equals 1/16. To find the combined probability of both cells producing recessive alleles, we apply the product rule once more: 1/16 * 1/16 equals 1/256.
Thus, the combined probability of both cells producing homozygous recessive offspring for gene Q after meiosis II is 1/256.