Answer:
Stimulus
Explanation:
The answer is stimulus. In plural it would be stimuli.
Krypton's atomic number is 36. This tells us that an atom of krypton has 36 protons in its nucleus<span>.</span>
Both "depends upon the binding of that substance to a specific site on the membrane protein" and "depends upon movement of proteins from one side of the membrane to the other" are correct.
The saturation effect prevents statement 2 from being true.