In a diploid organism, how are allele pairs separated into gametes?

• A. They separate, so each gamete gets one allele
• B. Random fusion of gametes
• C. They stay together in the same gamete
• D. They recombine to form new alleles

Answer: (A)

During meiosis, the two versions of every gene (the alleles) separate so that each gamete receives only one allele for that gene. This happens when homologous chromosomes are pulled into different gametes during meiosis I, ensuring that a fertilized zygote gets two alleles—one from each parent—again restoring diploidy. This segregation is the basis of Mendel’s law of segregation and is a key source of genetic variation because the specific allele a gamete carries is determined randomly.

The other ideas don’t fit as well: fertilization is the fusion of gametes, not the separation of alleles; keeping both alleles in the same gamete would violate how meiosis distributes genetic material; and recombination can shuffle alleles between genes but doesn’t create new alleles for a single gene in the way described by separating them into gametes.