Question

20 mark for review a cell signaling pathway begins when a hormone binds to its receptor. after binding, relay molecules within the cell become activated and trigger cellular responses. when drug k is added to cells, the cellular response is heightened and prolonged. which of the following mechanisms best explains how drug k increases the cellular response? a drug k inhibits the activation of the receptor protein. b drug k promotes the activation of relay molecules. c drug k inhibits the deactivation of the receptor protein. d drug k promotes the circulation of relay molecules.

Explanation:

Cell signaling pathways rely on activated receptors and relay molecules to trigger responses. A heightened, prolonged response means the signaling is amplified or sustained:

• Option A would reduce signaling, so it is incorrect.
• Option D: Relay molecules act intracellularly, so circulation is not relevant to their activation effect, making it incorrect.
• Option B promotes relay molecule activation, but Option C prevents receptor deactivation, which directly sustains the initial signal trigger, leading to a prolonged, heightened cellular response as the receptor remains active to continue initiating signaling cascades.

Answer:

C. Drug K inhibits the deactivation of the receptor protein