Nondisjunction and chromosomal disorders Original Scenario-Based Practice

Questions

1. 1.

   In an orbital genetics sanctuary, biologists observe meiosis in the celestial silk-moth (Aetheria bombyx), a diploid organism with $2n = 10$. During micro-imaging of spermatogenesis in a single primary spermatocyte, one pair of homologous chromosomes fails to separate during anaphase I, but meiosis II proceeds normally in all daughter cells. If each of the four resulting gametes fertilizes a normal ovum ($n = 5$), what chromosomal compositions will be found in the resulting embryos?

   • A) Two normal diploid embryos ($2n = 10$), one trisomic embryo ($2n + 1 = 11$), and one monosomic embryo ($2n - 1 = 9$)
   • B) Four triploid embryos ($3n = 15$) due to complete spindle failure
   • C) Two trisomic embryos ($2n + 1 = 11$) and two monosomic embryos ($2n - 1 = 9$)
   • D) Four abnormal embryos that all carry an extra chromosome ($2n + 1 = 11$)

Answers and step-by-step solutions appear after you finish the test.