Final answer:
The incorrect statement about the cell membrane is that protein receptors are only on the exterior of the cell. Proteins are found on both the interior and exterior surfaces, and carbohydrates on the cell membrane assist with cell communication.
Step-by-step explanation:
The statement that is not true about the cell membrane is that Protein receptors are found on the exterior of the cell only. In reality, protein receptors can be found both on the exterior and interior surfaces of the cell membrane. Phospholipids in the membrane are indeed fluid, allowing for movement within the membrane. The polar and hydrophilic phospholipid heads are attracted to water, facing the aqueous environments both inside and outside the cell, while the hydrophobic tails face inward. Carbohydrates, which are present on the exterior surface of the cell membrane, play a crucial role in cell communication.