Final answer:
The coiled tubular portion of the nephron connected to Bowman's Capsule where most filtrate reabsorption occurs is the proximal convoluted tubule (PCT).
Step-by-step explanation:
The coiled tubular portion of the nephron that is connected to Bowman's Capsule and is confined to the renal cortex, where most of the filtrate is reabsorbed, is the proximal convoluted tubule (PCT). In the PCT, filtered fluid that is collected by Bowman's capsule is reabsorbed. The PCT is composed of simple cuboidal cells with prominent microvilli, known as a brush border, that significantly increase the surface area for absorption and secretion of solutes such as sodium (Na+), chloride (Cl-), and glucose. These cells are highly active in transporting ions across their membranes and, therefore, have a high concentration of mitochondria needed for ATP production, the energy source for this active transport.