OCR GCSE Biology Practice Exam 2026 – Comprehensive All-in-One Guide to Exam Success

The correct choice highlights the role of receptor molecules in facilitating communication between cells. Receptor molecules are specialized proteins embedded in the cell membrane that respond to external signals. When these signals, such as hormones or neurotransmitters, bind to the receptor, they initiate a response inside the cell, allowing it to carry out specific functions or communicate with other cells. This is fundamental for processes like hormone signaling, immune responses, and neurotransmission.

Phospholipids mainly form the structural foundation of the cell membrane, creating a barrier that separates the cell's interior from the external environment, but they do not directly contribute to communication. Cholesterol is involved in maintaining membrane fluidity and stability, and while proteins are involved in various functions within the membrane, including transport and structural support, it is specifically receptor molecules that play the critical role in the signaling processes that are essential for cell communication.