1. Explain the differences between an intron and an exon? (4pts) 2. Why do you see different size bands in Homozygous recessive, Homozygous dominant and Heterozygous student sample in PTC experiment? (4pts) 3. In the PTC lab, we determined the frequency of two alleles, the “+allele” and the “- allele” in a sample population (our class). What was the difference between these two alleles? (4pts) 4. Define evolution be sure to include in your definition what actually evolves. (Spts) 5. Describe the principles of natural selection. (5pts)