Final answer:
When insecticides interfere with the removal of acetylcholine from the synaptic cleft, it can lead to prolonged muscle contraction. This occurs because the insecticides inhibit the activity of the enzyme acetylcholinesterase, resulting in an accumulation of acetylcholine and continuous muscle stimulation.
Step-by-step explanation:
When some insecticides interfere with the removal of acetylcholine from the synaptic cleft, it can lead to prolonged muscle contraction. Normally, after acetylcholine transmits the nerve impulse across the synapse, the enzyme acetylcholinesterase breaks it down to prevent continuous stimulation of the muscle. However, these insecticides inhibit the activity of acetylcholinesterase, resulting in an accumulation of acetylcholine in the synaptic cleft, which then continues to stimulate the muscle. This can cause muscle spasms, twitching, and even paralysis.