I am teaching basic vector algebra to senior high school students. I give them some famous examples of vector applications in geometry and physics, such as finding the angle between two no-co-planar lines in 3D, determining the static electric field at a point due to some charges, finding the direction at which a boat must go on the river, etc.
One student asked me, is there any application of vector to things that are specific to biology or chemistry?
Edit: I incline to applications that heavily emphasize the usage of both vector's magnitude and its direction. But modeling with vector for the sake of simplicity is also welcome. Overkill modeling with vector is not welcome!
Part of my current research is applying graph spectral methods to real-world complex networks (such as biological neural networks). In particular, I'm comparing how networks drawn using the eigenvectors of the network's Laplacian matrix compare to how they are arrange physically in the organism. Hopefully, this method can give insight into the biological network.