Inherited traits and variation Transitional Reasoning Practice

Questions

1. 1.

   A researcher investigates the inheritance of two unlinked traits in a sexually reproducing beetle species: body color governed by alleles B (brown) and b (black), and wing texture governed by alleles S (smooth) and s (wrinkled). A male beetle heterozygous for both traits (BbSs) is crossed with a homozygous recessive female beetle (bbss), producing hundreds of offspring exhibiting four distinct phenotypic combinations in approximately equal frequencies. Which biological mechanism occurring during gamete formation in the male beetle primarily accounts for the generation of these four diverse phenotypic classes in the progeny?

   • A) Crossing over between sister chromatids during prophase II generates novel alleles that convert recessive traits into dominant ones.
   • B) A second round of DNA replication during interkinesis multiplies chromosome combinations before gamete packaging.
   • C) Environmental temperatures during embryogenesis induce the differential expression of identical paternal alleles across offspring.
   • D) The independent orientation and segregation of non-homologous chromosome pairs during meiosis I produce four distinct gametic allele combinations in equal proportions.

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