The process is called photosynthesis and it takes place in the chloroplast of a plant cell
If organisms that lived there before had exceeded the carrying capacity then the ecosystem would no longer be able to sustain life
I think the answer is skin. Skin contains sweat glands which secrete a fluid waste called sweat or perspiration; nonetheless, its primary functions are temperature control and release of pheromone. Its role as a part of the excretory is therefore minimal. Additionally, sweating also maintains the levels of salt in the body.