Question

fraternal twins, while conceived at the same time, are not genetically identical. which statement best explains why these siblings are genetically different from each other? one chromosome from each pair randomly passes to the sex cells during meiosis and leads to differences between the siblings. one chromosome from each pair randomly passes to the sex cells during fertilization and leads to differences between the siblings. mutations occur during meiosis and lead to differences between the siblings. mutations occur during fertilization and lead to differences between the siblings.

Explanation:

• Meiosis and Chromosome Segregation: During meiosis (the process of forming sex cells - sperm and egg), homologous chromosome pairs separate. One chromosome from each pair randomly goes to a sex cell. When two sex cells (sperm and egg) fuse during fertilization, the combination of chromosomes from these sex cells (which have a random assortment of chromosomes from each parent due to meiosis) leads to genetic variation. Fraternal twins are formed from two different egg - sperm combinations.
• Fertilization and Chromosome Contribution: Fertilization is just the process of combining gametes (sex cells). Chromosome assortment in sex cells occurs during meiosis, not during fertilization.
• Mutations during Meiosis vs Fertilization: Mutations during meiosis are relatively rare and not the main reason for the genetic difference between fraternal twins. The main reason is the normal process of chromosome segregation during meiosis that creates different combinations of parental chromosomes in sex cells. Mutations during fertilization (which is a very short - lived process of cell fusion) are even less likely to be the cause of the genetic differences between fraternal twins.

Answer:

One chromosome from each pair randomly passes to the sex cells during meiosis and leads to differences between the siblings.