List the structure(s) that form the boundary between the inside and the outside of each cell in Model 2.

Explanation:

An animal cell has a cellular membrane, which keeps its contents inside, differentiating the inside from the outside. A plant cell has both a cellular membrane and a cell wall, which keeps its shape and prevents it from going through lysis and cellular destruction

tl;dr

Animal cell: cell membrane

Plant cell: cell wall, cell membrane