D. Certain genes are turned on and others are turned off; this action produces adult cells that are specialized
Answer:
All cells are surrounded by a cell membrane. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others.
Explanation:
D. it serves as a link between membrane proteins on adjacent membranes.
Answer: Closed
Explanation:
At resting membrane potential( RMP) sodium channels remained shut, this is because , previously in depolarisation,the voltage gated sodium channels were opened for sodium to diffuse into the Axon. However these channels closed after reaching their refractory period,s.
Therefore a change in the extracellular concentration of sodium will not open them