What structure surrounds the cytoplasm in plant cells and controls what enters and exits the cell?

The correct answer is the cell membrane, which surrounds the cytoplasm in plant cells and is responsible for controlling the movement of substances in and out of the cell. The cell membrane, made up of a phospholipid bilayer with embedded proteins, selectively allows certain molecules to pass while blocking others. This selective permeability is crucial for maintaining the proper internal environment of the cell, including the concentration of ions and nutrients necessary for cell function.

While the cell wall also surrounds plant cells, it provides structural support and protection but does not function actively in regulating the exchange of materials. The nucleus is the control center of the cell, housing the genetic material, while the cytoskeleton provides structural support and helps with cellular movement but does not enclose the cytoplasm or regulate transport across the cell membrane. Understanding these distinctions clarifies the specific roles of each component in plant cell structure and function.