Both epinephrine (a tyrosine derivative) and glucagon (a peptide hormone) increase glucose export from the liver into the bloodstream. each ligand binds a different receptor, but both lead to an activation of pka. how does this happen?

The answer is that the two receptors work as binders , thereby, they activate the same Ga subunit, Gsa, and this indirectly to the activation of PKA.

Explanation:

Note that, the action that occurred within the cell depends on heterotrimetric G protein that was activated by the receptor. In specificity, the receptors for glucagon and epinephrine interact with the intracellular Gsa subunit of a heterometric protein. Activation of Gsa leads to the same downstream which signal events, hence the same cellular responses despite the difference between the ligand-receptor interaction.

chert is a sedimentary rock composed of microcrystalline or cryptocrystalline silica. with this little bit of information, you can come to the conclusion that your answer is c.  

explanation: