What are two important uses of petroleum

the two f's; fuels (oil) and feedstocks (making chems., plastics.. etc)

hormones in blood stream

image: dtc.ucsf.edu

endocrine glands secrete hormones into the blood stream near them; the hormones then travel in our bloodstream until it reaches its destination, called a target cell, in distance parts of the body. in the target tissue, hormones lock onto the target’s plasma membrane, called the receptor site.

maritime tropical may be your answer.