<prompt> Renal filtration fraction is calculated asRenal plasma flow RPFGFRGFRRPFRPF x GFR Total Blood flowNone of the above  <response>: Renal filtration fraction GFRRPF The filtration fraction, is normally 0.16-0.20. The GFR varies less than the RPF. When there is a fall in systemic blood pressure, the GFR falls less than the RPF because of efferent aeriolar constriction, and consequently the filtration fraction rises. 