Experiments performed with biological systems require a buffer that will not interfere with the stability and activities of the biological components. In 1966, Norman Good and his colleagues began a series of investigations that established criteria for new zwitterionic buffers that would be optimal for experimentation with biological systems. These criteria included:

the relative standard reduction potential of the half-cell in which reduction occurs; more positive than the other half-cell. reduction is a chemical process in which electrons are added to an atom or an ion; it always occurs accompanied by oxidation of the reducing agent.

instead of copying and pasting things off of tests or work done on computer which im sure you did, try and read over the question carefully