What are the differences between primary and secondary succession

The frequency of alleles in a population that is in hardy weinberg equilibrium? a . changes in each successive generation b. is less important than the frequency genotypes c. shows evidence of the process of natural selection d. remains the same over several generations

There are fewer than 100 naturally occurring elements in the universe, but there are millions of different unified substances. explain how this can be true.

Has anyone taken the genetics unit test in connexus? not looking for answers, just a little bit what to expect and some with studying.