Materials are transported within a single celled organism by the

You may be referring to the cytoplasm here. That is the "filling" within the cell. But if you are looking for specific transport of proteins, the ER folds proteins and then transport vesicles move them to the Golgi.

The cytoplasm (is inside the cell) or it might be the cell membrane which is permeable (meaning it allows things to pass through it)

Very hard to understand