An organ system is made from a group of different ... female part of the flower which collects pollen grains. During plant reproduction, pollen grains need to move to the stigma of a flower.

In both flowering plants and animals, these reproductive cells ... Chemotaxis acts a bit like a navigation system where the growing tip of the pollen tube homes in on the source of these protein ...

Can be used to recap on sexual reproduction in plants or could lead into a classroom discussion on multicellular organisms.