The physiological process being investigated is diffusion (specifically, the diffusion of iodine molecules across a selectively permeable membrane).

a)
The physiological process being investigated is diffusion (specifically, the diffusion of iodine molecules across a selectively permeable membrane).

b)
Inside: Blue-black
Outside: Yellowish-brown

c)
Visking tubing acts as a partially permeable membrane, allowing small molecules to pass through but not large ones. Iodine molecules are small enough to diffuse from the region of higher concentration (outside the tubing) to the region of lower concentration (inside the tubing). The starch molecules in the banana paste are too large to pass out of the tubing. Once inside, the iodine reacts with the starch, resulting in a blue-black color. The solution outside remains yellowish-brown because starch cannot diffuse out to react with the iodine.