Final answer:
Pseudopodia is the protist movement structure that works by streaming of the cytoplasm to form projections of the body surface.
Step-by-step explanation:
The protist movement structure that works by streaming of the cytoplasm to form projections of the body surface is pseudopodia. Pseudopodia are temporary extensions of the cell membrane that can change shape and move the protist by extending and retracting.
Learn more about Protist movement structure