Given the task definition and input, reply with output. Given a scientific passage and an answer, generate a question for the given answer.

Passage: Ingestive protists ingest, or engulf, bacteria and other small particles. They extend their cell wall and cell membrane around the food item, forming a food vacuole . Then enzymes digest the food in the vacuole. Answer: food vacuole
Ingestive protists extend their cell wall and cell membrane around the food item, forming a what?