Answer:
physical change alert the form of appearance of the matter but does not turn any substance in the matter into a different substance.
Answer:
The ligand has only one receptor that it is able to bind to
Explanation:
The shape of the ligand and its corresponding receptor allow there to be specificity. For example, receptors for ligand A would be found on the target immune system cells and not on cardiac muscle cells or skin epithelial cells. Therfore, even though the cardiac muscle cells or the skin epithelial cells would be exposed to ligand A, they would not be able to bind to it and therefore could not react because of the specificity of the receptor of ligand A at that moment
The parts of the circulatory system include the heart, the lungs, and all the veins and arteries.
