Chi-square analysis of crosses Original Scenario-Based Download PDF

Questions

1. 1.

   In an orbital bio-dome on Kepler-186f, xenobiologists cross two heterozygous glimmering beetles displaying an intermediate shimmering teal carapace to test whether shell coloration follows single-gene incomplete dominance. Among 400 recorded progeny, they observe 85 dark blue, 215 shimmering teal, and 100 phosphor green carapaces. Given an expected 1:2:1 phenotypic ratio and a critical $\chi^2$ value of 5.99 at the $p = 0.05$ level ($df = 2$), which option gives the correct calculated chi-square value and biological conclusion?

   • A) $\chi^2 = 4.50$; reject the null hypothesis because the observed counts significantly diverge from the expected incomplete dominance ratio.
   • B) $\chi^2 = 3.375$; fail to reject the null hypothesis, supporting the hypothesis of single-gene incomplete dominance.
   • C) $\chi^2 = 3.375$; reject the null hypothesis because three phenotypic classes cause the statistic to exceed permissible variation.
   • D) $\chi^2 = 2.25$; fail to reject the null hypothesis because only the dark blue class displays any mathematical variance.