Final answer:
The plasma membrane is a selectively permeable membrane, managing the entry and exit of substances from the cell. Plant cells have an external cell wall composed of cellulose, which offers added structural support.
Step-by-step explanation:
The plasma membrane is a selectively permeable membrane, this means that it allows some materials to freely enter or leave the cell, while preventing certain other materials. Its structure is composed of a bilayer of phospholipids with proteins and carbohydrates attached to it which help in transporting materials and identifying the cell, forming a complex protection system.
In plant cells, a cell wall composed of cellulose is located outside the plasma membrane. It provides an additional layer of structural support and protection. Unlike the plasma membrane, the cell wall does not control the movement of substances but it does contribute to the overall function and structure of the plant cells.
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