The proteins in the cell membrane allow substances to come or go, based on their concentrations. this is an important part of which maintains the immediate conditions necessary for life. a) osmosis eliminate b) metabolism c) homeostasis d) endocytosis

C) homeostasis

Explanation:

Homeostasis is the ability of the body, organelle or cell to resist change in order to maintain a stable, internal environment. The receptor proteins are present inside the lipid bilayer which enable the transport of substances in and out of the cells. This procedure maintains the homeostasis in the way it maintains the internal environment by maintaining the incoming of substances which are required by the cell and transport the substances which are not required by the cell.  

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle

a. to encourage apoptosis