Botulism toxin disrupts motor control by Botulism toxin disrupts motor control by blocking the release of acetylcholine by motor neurons. blocking acetylcholine receptors on muscle cells. causing demyelination of motor neurons. killing motor neurons. blocking inhibitory signals to motor neurons.

Botulism toxin disrupts motor control by blocking the release of acetylcholine by motor neurons.  

Explanation:

Acetylcholine is the principal neurotransmitter in motor neurons. If there is no release of acetylcholine from the presynaptic motor neuron, the ion channels will not open. If the ion channels do not open, Na+ cannot enter the postsynaptic membrane to start an action potential. As a result, the muscle can not move.

The ion channels have a specif receptor for acetylcholine. When acetylcholine binds to the receptors, the channels open. With the ion channels open, Na+ can enter the postsynaptic membrane to start an action potential. This does not happen in the presence of botulism toxin since it blocks the release of acetylcholine.

thinking it would be physical characteristics

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.