Explain facilitated diffusion. Where is this happening in the cell? Is the substance moving up or down a concentration gradient? When will this process stop?

Dthrough a slow process

The rate that would change would be the  searching efficiency/attack rate. there are only two other rates in this model: the  growth rate of prey, and the  predator or consumer mortality rate.the  searching efficiency/attack rate is what indicates how effectively can a predator capture its prey whether in the searching process or actual capturing/attacking process. 

It forms into a full nebula/star