Inherited traits and variation Original Scenario-Based Download PDF

Questions

1. 1.

   In an orbital bio-dome, researchers study iridescent crystal-beetles whose carapace patterns depend on multiple gene loci located along the same chromosome pair. Even when two identical heterozygous parent beetles are bred under completely uniform environmental conditions, each offspring in the clutch displays a novel, unique blend of ancestral color markings along its shell segments. Which cellular process occurring during gamete production is directly responsible for breaking linkage groups and generating these new combinations of maternal and paternal alleles on single chromosomes?

   • A) Random accumulation of somatic mutations during post-zygotic mitotic divisions
   • B) Complete failure of sister chromatid separation during anaphase II
   • C) Crossing over between non-sister chromatids of homologous chromosomes during prophase I
   • D) Environmental alterations of cytoplasmic mRNA transcripts during embryonic cleavage