One year. It takes 365 days for Earth to orbit the sun.
I think it may be conservation.
Non polar molecule move across a membrane through simple diffusion, when moving up their concentration gradient. Simple diffusion involves movement of molecules through a membrane without the help of integral membrane protein. These molecules are driven by the force of diffusion. This is different from facilitated diffusion where molecules only move with the aid of integral protein in the membrane.
Olafactory bulbs because it has to do with nerve signals and neurons. Brain because it is the center of the nervous system and the closest to the nose in terms of the nervous system.
