Answer:
a) Acetylcholine is degraded by acetylcholinesterase.
Explanation:
After it binds for its receptor on the plasma membrane of the postsynaptic cell, acetylcholine must be removed in order to prevent repeated stimulation. Acetylcholinesterase is enzyme for the inactivation of acetylcholine, present at all cholinergic synapses. This enzyme hydrolyses acetylcholine and breaks it to the acetate and choline. Choline can be reused for the synthesis of the new acetylcholine molecule so it is taken back into the presynaptic cell.
A, B and C are the events that will cause an ecological disturbance.
Rationale:
A. Introduction of a new species: When a new specie is introduced, it increases the competition in ecosystem with the native species for food, water, space and shelter. This affects the reproductive success of the native species and thus the dynamics of ecosystem.
B. Climate change: Climate change is different from a simple change of weather. The best example would be of Antarctica where the ice is melting fast due to the global warming. The native species find it harder to adapt to the warm temperatures.
C. Late spring snowstorm: Spring is the season where the plants grow and animals shed their fur. When snowstorms occur in this season they harm these plants and animals that live there.
