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GATE 2020 BM – Question 46

Mammalian Cell Biology, Human Anatomy and Physiology · Excretory System · 2 marks · Multiple choice

Glomerular filtration is modeled as flow through a flat membrane with cylindrical pores of radius 1 nm and length 60 nm. Fluid viscosity is 0.002 Pa s. Pores occupy 5% of a 1.5 m² membrane. Blood-side pressure is 8000 Pa and filtrate-side pressure 6200 Pa. Find nearest filtration rate in cm³/min.

  1. 0.14
  2. 1.40
  3. 8.43
  4. 84.37

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Correct answer: (C) 8.43

Explanation

For one cylindrical pore, Poiseuille flow is πr⁴ΔP/(8μℓ). Total pore count equals open area divided by πr², so total flow=Apore r²ΔP/(8μℓ). Here Apore=.05×1.5=.075 m² and ΔP=1800 Pa. Substituting gives 1.40625×10⁻⁷ m³/s. Convert with 10⁶ cm³/m³ and sixty seconds/min: 8.4375 cm³/min, C.