At the axon tips, electrical signals change to a chemical form, allowing the messages to cross the gap in the synapse. true or false

True.

Explanation:

At the axon tips, there are vesicles containing chemicals called neurotransmitters (NT). On the arrival of the electrical impulse, calcium ions enter and stimulate the release of those NT via exocytosis into the synaptic cleft.

The NT will diffuse across the cleft and bind to specific receptors on the post-synaptic membrane to initiate an action.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products