Mutations are not a mechanism for evolution.
Answer is A
Firstly axon must reach the threshold level and then depolarisation occurs. Depolarisation phrase means sodium enters and potassium leaves the axon . Choice C can't be because main idea is the entering of sodium ions.
Nerves that detect deep pressure are called Pacinian corpuscles.
Pacinian corpuscles are microscopic onion-shaped nerve structures that are situated in the dermis and hypodermis. Pacinian corpuscles detect deep pressure and vibration. This nerve has a myelinated nerve ending in the middle of its structure and the external layer contains flattened cells, a lymph-like fluid and collagen fibers. The structure of pacinian corpuscles provides a fast response and rapid recovery by transmitting fast events. This make them sensitive to pressure and vibration.
Homeostasis is maintained by the respiratory system in two ways: gas exchange and regulation of blood pH. Gas exchange is performed by the lungs by eliminating carbon dioxide, a waste product given off by cellular respiration.
