Final answer:
The statement that some acetylcholine diffuses out of the synaptic cleft is true, as acetylcholinesterase degrades unbound ACh to prevent continuous muscle stimulation.
Step-by-step explanation:
The question is about acetylcholine (ACh) diffusion in the synaptic cleft during neurotransmission. ACh is released by the presynaptic neuron and must diffuse across the synaptic cleft in order to bind with ACh receptors on the post-synaptic neuron.
This diffusion process is essential for the continuation of the nerve signal. However, not all ACh binds to receptors. Some molecules may diffuse out of the synaptic cleft or become degraded by the enzyme acetylcholinesterase (AChE), which is present in the synaptic cleft. This enzyme rapidly breaks down ACh into acetyl and choline to prevent continuous stimulation of the muscle, which would lead to unwanted extended muscle contraction. As a result, some ACh does indeed diffuse out of the synaptic cleft, making the statement True.