<prompt> Essential difference between serum and plasma is in content ofProteinSugarFatRBC  <response>: Ans: a Protein Ref: Ganong 22nd edp.543Serum Plasma - fibrinogen, clotting factors II, V, VIII.Serum has higher serotonin content because of breakdown of platelets during clotting.Normal plasma volume is about 5 of body weight, -3500 ml in 70 kg man. 