If
a drug were found that blocked all calcium channels that are linked to
g-protein coupled receptors, would it completely block the use of calcium as
second messenger? explain your answer.

No, this drug will not completely block the use of calcium as second messenger.

Explanation:

No, because calcium is present both outside and inside cells and it participates in many cellular signaling processes other than those activated by G protein-coupled receptors, we can cite as an example of these activities: the dissemination of action potential; muscle contraction and cell proliferation.

Calcium is also released into the intracellular media reserves after being stimulated by different types of receptors and intracellular signaling pathways.

Finally, we must not forget that calcium signaling is also important for modeling apoptotic signaling pathways.

true, i don't really know what you're asking but from the info you provided im guessing the answer is true.