Final answer:
The combined probability of two identical heterozygous cells producing recessive alleles at the end of meiosis II is 25%.
Step-by-step explanation:
To calculate the combined probability of two identical cells that are heterozygous for gene Q producing recessive alleles (qq) after meiosis II, we use the principles of Mendelian genetics and probability rules. For each heterozygous (Qq) cell, during gamete formation, there is a 50% chance it will produce a gamete with the Q allele and a 50% chance it will produce a gamete with the q allele. Thus, when considering a single cell, the probability of producing a gamete with the recessive q allele is 1/2. The event of one cell producing a q allele is independent of the same event in another cell, and when independent events occur, we use the product rule to determine the combined probability. Hence, the combined probability that both cells produce a q allele is 1/2 multiplied by 1/2, which gives us 1/4 or 25%.