A Level Biology Practice Exam

What role do receptors play in cellular response?

1. They synthesize proteins necessary for response

2. They bind chemical signals, triggering a response by the cell

3. They transport molecules across the cell membrane

4. They catalyze cellular reactions

The correct answer is: They bind chemical signals, triggering a response by the cell

Receptors are specialized proteins located on the surface of or within cells that play a crucial role in facilitating cellular responses to external signals. When a chemical signal, such as a hormone or neurotransmitter, binds to a receptor, it triggers a cascade of internal processes within the cell. This binding is highly specific, allowing the cell to respond appropriately to various signals, which may include activating certain genes, initiating metabolic pathways, or causing changes in cell behavior. For instance, upon activation by the binding of a ligand, receptors can undergo conformational changes that lead to various downstream signaling events, effectively translating the external signal into a functional response inside the cell. This is essential for maintaining homeostasis and allowing cells to react to their environment. While the other options describe different cellular functions, they do not accurately reflect the primary function of receptors. For example, receptors do not synthesize proteins, transport molecules, or catalyze reactions directly; those roles belong to other types of proteins or cellular mechanisms. Hence, the role of receptors is pivotal in mediating and initiating cellular responses to chemical signals.