Filtration occurs due to which mechanism?

• A. Low pressure in the glomerulus
• B. High pressure forces fluid into Bowman's capsule where it is filtered
• C. Osmotic pressure in the tubules
• D. Active transport

Answer: (B)

Filtration is driven by a hydrostatic pressure gradient across the filtration barrier. The high hydrostatic pressure in the glomerular capillaries pushes water and small solutes across into Bowman's capsule, forming the filtrate. This process is passive and depends on pressure differences, not on energy-driven transport. Osmotic pressure in the tubules would oppose filtration rather than drive it, low pressure in the glomerulus wouldn’t push fluid out, and active transport is not involved in the filtration step.