Question

curare is a poisonous plant extract. curare molecules have a chemical structure like the neurotransmitter ach. curare can bind to the ach receptor site on the chemically gated ion channels in the motor end plate. even though curare will bind to the receptor site it will not open the ion channel and no ions will pass through. what do you think the symptoms of curare poisoning would look like? muscles will respond too quickly and cause a severe tremor. smooth muscles will become stimulated causing quick movement of nutrients through the digestive system. curare will only affect cardiac muscle, causing fibrillations of the heart. curare will only affect muscles with ach receptors, paralyzing them.

Explanation:

Curare binds to ACh receptor sites but doesn't open ion channels. ACh is crucial for muscle contraction. Without ion flow (due to blocked channels by curare), muscles with ACh receptors can't receive the proper signal to contract. So, these muscles would be paralyzed.

• For the first option: Since curare blocks the channel (not enhancing the response), muscles won't respond too quickly.
• For the second option: Smooth muscles' movement in the digestive system is not the main effect here as curare acts on ACh - related muscle (skeletal muscle mainly which has ACh receptors in motor - end plate context) not specifically on smooth muscle for quick nutrient movement in this poisoning mechanism.
• For the third option: Curare affects muscles with ACh receptors (not just cardiac muscle). Cardiac muscle has a different mechanism of contraction regulation compared to the ACh - dependent skeletal muscle (where curare acts as described).

Answer:

Curare will only affect muscles with ACh receptors, paralyzing them.