Need help with A,B and D please, thanks.

Under specific conditions, hemoglobin dissociates into its four subunits. The isolated a subunit binds oxygen, but the O2-saturation curve is hyperbolic rather than sigmoidal. In addition, the binding of oxygen to the isolated a subunit is not affected by pH, or the allosteric regulator BPG. Use your knowledge about hemoglobin and the information provided in this question to answer: a. Draw the expected O2 binding curves for tetrameric hemoglobin and for the isolated a subunit (draw them on the same axes). How can you explain their different behavior? b. Draw the expected Hill plot for tetrameric hemoglobin and for the isolated a subunit. c. What Hill coefficient ( n ) will you expect for tetrameric hemoglobin and for the isolated a subunit? d. How would you use each of these graphs to determine dissociation constants for the binding of oxygen to tetrameric hemoglobin and to the isolated subunit