In the concluding activity students construct a timeline that highlights the fact that most of life's history on earth has been in the form of single-celled organisms. Students explore some of the prevailing scientific ideas and the supporting evidence for them through readings and videotaped interviews of scientific experts. Students gain experience with the diversity of single-celled organisms through Winogradsky columns and microscope images. They then study the hypothesis for the evolution of cells with nuclei and other organelles, endosymbiosis, and the evidence for it. Finally, students reinforce their understanding of the structures and functions of the eukaryotic cell through analogies in a poster project.
Students then focus on meiosis and do a simulation of recombination.
This activity serves to introduce the other sources of variation needed for evolution. The lesson concludes with a poster session and a revisit of the timeline. Links to these documents are permitted and encouraged. No copies may be made without permission.