Genetic variation Transitional Reasoning Download PDF

Questions

1. 1.

   A researcher analyzes the gametes produced by a diploid animal with the genotype AaBb, where both gene loci reside on the same pair of homologous chromosomes. When meiosis occurs without any physical exchange between chromosomes, the organism produces only two distinct gamete genotypes. However, genetic analysis reveals that four distinct gamete types are regularly formed during gametogenesis. Which mechanism best explains the appearance of the additional gametic combinations in this organism?

   • A) Crossing over between non-sister chromatids of homologous chromosomes during prophase I exchanged alleles to form recombinant chromosomes.
   • B) Independent assortment of non-homologous chromosomes during metaphase I separated the linked alleles into novel combinations.
   • C) Random alignment and separation of sister chromatids during anaphase II created alternative allele linkages on the autosomes.
   • D) Random fertilization among existing gametes rearranged the maternal and paternal alleles into four distinct gametic types.