Associate Certified Entomologist (ACE) Practice Exam

What is the mechanism of action (MOA) for organophosphates?

1. Blocks neurotransmitter receptors

2. Inhibits acetylcholinesterase

3. Enhances energy production

4. Inhibits synaptic transmission

The correct answer is: Inhibits acetylcholinesterase

Organophosphates work by inhibiting acetylcholinesterase, an enzyme that is crucial for the breakdown of the neurotransmitter acetylcholine in the synaptic cleft. When organophosphates inhibit this enzyme, acetylcholine accumulates, leading to prolonged stimulation of the post-synaptic receptors. This overstimulation can result in various symptoms, ranging from muscle twitching to paralysis, and can be fatal if exposure is significant. The significance of this mechanism lies in its impact on the nervous system's function, where the normal cycle of neurotransmission is disrupted. The prolonged presence of acetylcholine in the synapse leads to continuous activation of muscles, glands, and the central nervous system. Understanding this process is essential for both pest control and safety measures when handling organophosphate pesticides. The other options do not accurately represent the physiological impact of organophosphates on the nervous system, as they either suggest a different mechanism or do not relate to the specific effects observed with this class of chemicals.