Biology #23. Answer should be D. He says that teeth are made of only ectoderm, but this is incorrect. Tooth enamel is made of ectoderm, but dentin is derived from mesoderm. I found this info on page 136 of Histology: a Text and Atlas by Michael H. Ross and Wojciech Pawlina.
Biology #31
B, not E. Someone tell me if I'm way off on this one. He says that "no net migration" is a condition for Hardy-Weinberg Equlibrium. My problem with this is the word "Net." Net migration to me implies that migration could occur, but the population size remains the same. The purpose of no migration is to eliminate gene flow (most sources I've read say "no gene flow" or "isolation"). If you started with a population of 50, 10 members were lost to emmigration, and 10 new members were gained to immigration, you would have no NET migration, but gene flow would have still occurred. I think that "no migration" would make choice E correct, but the word "net" makes it incorrect.