When a drug binds to a receptor in the body , the receptor is activated or inactivated.
Molecules such as hormones, drugs or neurotransmitters that bind to a receptor are called ligands. The binding can be specific and reversible. A ligand may activate or inactivate the receptor; activation may increase or decrease a particular cell function. Each ligand may interact with multiple receptor subtypes.
Answer:
A) the pressure of Earth's crust upon Earth's mantle
This is cyclic change because the population is consistently going up and back down.
Convection Current
This happens when there is a noteworthy contrast in temperature between two sections of a liquid. At the point when this temperature distinction exists, hot liquids rise and cool liquids sink, and after that streams, or developments, are made in the liquid