Final answer:
Blocking ACh receptors with a poison would prevent muscle contraction, as the transmission of the signal for contraction would be inhibited. This is evidenced in conditions like myasthenia gravis and with substances like d-tubocurarine and Botox.
Step-by-step explanation:
If a poison blocks the acetylcholine (ACh) receptors, it would predictably lead to the inhibition of muscle contraction. This prediction is based on the fact that acetylcholine must bind to its receptors on the muscle fibers to initiate contraction. Once ACh is released from the motor neuron, it crosses the neuromuscular junction and binds to ACh receptors on the muscle cell's membrane. This binding triggers a sequence of possibilities that lead to the contraction of muscles. Therefore, if a poison blocks ACh receptors, it prevents acetylcholine from binding, which halts the transmission of the signal required for muscle fibres to contract.
Considering the disease myasthenia gravis, where ACh receptors are impaired due to autoantibodies blocking these receptors, the result is extreme muscle weakness. Another example is d-tubocurarine, which competitively blocks acetylcholine at the neuromuscular junction, causing muscle relaxation and paralysis. Similarly, Botulinum toxin (Botox) works by decreasing the release of acetylcholine from motor neurons, which also leads to an inability of the muscle to contract.