<span>the intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment.
</span>
Two individual flatworms must transfer sperm to each other
Some advances is that organelles, cells, and the difference between the cells of a plant and a cell of an animal. This was an advance because not only did we discover new things but we learned how or body functions with them and how they work. Hopefully you got what you were looking for. :)
