n the space below, briefly explain why the average times for the two CO2 molecules you calculated should have been similar (or at least not significantly different). If a CO2 molecule starts out surrounded by other CO2 molecules, does this influence how quickly it will reach the other side of the leaf? You might find it helpful to reset the simulation and to re-examine the initial configurations of molecules. Collisions influence how molecules move, but do molecules only collide with other molecules of the same substance?

No, the neurons don't use diffusion to transfer messages rather they employ the use of electrical impulses which are very fast for example, if we drop something accidentally on our foot we immediately move back to prevent ourselves from injury this quick reaction is possible because the signals are transferred in the form of electrical impulses.If diffusion was there to transfer the message then it would have taken very long time and our foot would have been bleeding too as diffusion process is relatively much slower.

This is due to collision of CO2 molecule with other molecules of CO2 and vander vals interaction between them which results in slow down of CO2 molecule and the CO2 molecules also collide with walls of leaf as well which also decreases the speed of CO2 molecule resulting it in taking more time.