Biology · Cell Structure and Function

The correct answer is Plasma membrane because it is the structure that forms the boundary of both plant and animal cells, controlling the movement of substances in and out of the cell. The plasma membrane is selectively permeable, meaning it allows certain substances to pass while blocking others.

In contrast, Mitochondria are organelles responsible for energy production and do not serve as a barrier. The Golgi apparatus is involved in processing and packaging proteins and lipids, but it does not regulate substance entry or exit. Lastly, the Cell wall provides structural support in plant cells but does not function as a selective barrier like the plasma membrane.

Mitochondria are known as the powerhouse of the cell, responsible for producing energy through cellular respiration. However, they do not serve as a boundary controlling entry and exit of substances in the cell.

The Golgi apparatus is involved in modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles. It does not function as a boundary for controlling substance movement.

The plasma membrane is a crucial structure in both plant and animal cells that serves as a selective barrier, regulating what enters and exits the cell. This is the correct answer.

The cell wall is a rigid structure found in plant cells that provides support and protection. While it does help maintain cell shape, it is not involved in the selective regulation of substances entering or exiting the cell like the plasma membrane.