Which of the Following Statements is TRUE

Question

Which of the following statements is TRUE?
A)Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior.
B)To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol.
C)A cell-surface receptor capable of binding only one type of signal molecule can mediate only one kind of cell response.
D)Any foreign substance that binds to a receptor for a normal signal molecule will always induce the same response that is produced by that signal molecule on the same cell type.

Accepted Answer

Hydrophilic extracellular signal molecules cannot easily cross the lipid bilayer of the plasma membrane, so they bind to cell-surface receptors to initiate a cellular response.