Each organism is unique because of genetic variation. Each set of genes we inherit from our parents codes for a specific trait. And our DNA is a blueprint for these traits. Not everybody contains the same genes and that is why we are all so beautifully unique.
Blood pressure forces plasma minus its macromolecules (e.g., proteins) from the glomerular capillaries into the Bowman's capsule, which is continuous with the proximal convoluted tubule.