Aprotein purification table is shown below and partially filled in. which statement is true? step in purification activity (units) total protein (mg) specific activity ( ) extent of purification ( ) overall yield ( ) crude homogenate 1000 2000 0.5 1 100 ion-exchange chromatography 750 500 1.5 75 affinity chromatography 300 10 _ 60 30 a. the units of extent of purification are mg per ml. b. ion-exchange chromatography is the more powerful purification step. c. specific activity is measured in units of activity per mg protein. d. the overall yield after affinity chromatography is high. e. all statements are tru