Membrane proteins are among the most important proteins biologically because they allow the cells to communicate with their environments. these membrane proteins are responsible for all but which process?
a) triggering ion channels
b) identifying foreign cells
c) regulating intake of oxygen
d) activating growth hormone reactions

C)regulating intake of oxygen  

Explanation:

Plasma membrane proteins perform a variety of functions: they act preferentially on transport mechanisms, organizing true tunnels that allow substances to pass into and out of the cell, function as membrane receptors, and receive signals from substances that carry some message to the cell, favor adhesion of adjacent cells in a tissue, serve as anchor point for the cytoskeleton. In addition, these proteins trigger ion channels, identify foreign cells in the body, activate growth hormone reactions, but do not regulate oxygen intake regulation.

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