Final answer:
The plasma membrane does not include cytoskeletal filaments, which are part of the actin cortex just beneath the plasma membrane.
Step-by-step explanation:
The plasma membrane does not contain cytoskeletal filaments. The plasma membrane is composed of a phospholipid bilayer with embedded proteins, and it functions to separate the internal contents of the cell from its surrounding environment. It is involved in regulating the passage of substances like organic molecules, ions, water, and gases such as oxygen. Right beneath the plasma membrane is the actin cortex, which consists of crosslinked actin filaments, but these filaments are not part of the plasma membrane itself. Additionally, the plasma membrane does not include membranes of the mitochondria or chloroplasts, which are separate entities.