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Lesson and Simulation on Natural Selection and Homeostasis in the Mussels Mytilus edulis

The 2016 AP Biology exam opened with a fantastic free response question that asked students to incorporate multiple biological concepts. Students were asked to understand:

  • Tolerance levels of mussels in different levels of salinity in the Long Island Sound.
  • How different alleles of the same gene can produce different functioning enzymes.
  • Regulation of water balance in different salinities.
  • Adaptations of mussels in different salinities.

I loved this AP Biology exam question because it incorporates the Big Ideas of biology, ecology, genetics, homeostasis, and evolution. The question from the College Board can be found HERE. This question is based on a research paper from Koehn, Newell, and Immermann (1980) called Maintenance of an aminopeptidase allele frequency cline by natural selection. I created a simulation to help my students work through the paper and teach the principles of the Hardy-Weinberg equilibrium. HERE is the simulation.

HERE  is how I structured my lesson.