Question

A cell has a deficiency that prevents it from regulating the movement of water, food, and wastes into and out of the cell. whcih part of the cell structure that is most likely affected.

Answer 1

The plasma membrane (cell membrane).
It normally controls selective permeability — moving water, nutrients and wastes via lipid bilayer properties and membrane proteins (channels, carriers and pumps). A defect in the membrane itself or its transport proteins would cause the problem you describe.