1. Can some explain the penetrance and expressivity to me, and how the relate to the field of genetics.

2. Can anyone explain to me how the external and internalenvironment can affect gene expression

3. What are sex-limited and sex influenced traits?

4. If (almost) all cells contain the same DNA, then how do they become speicallized different cell types?

5. Why is it interesting that all animals examined  so far have Hox genes?

6. How are terrestrial, freshwater and marine environments different? What unique challenges does each present?