Which of the following observations best supports the conclusion that dolphins and sharks do not have a recent common ancestor?
a. dolphins form social groups, but sharks are solitary.
b. dolphins hunt during the day, but sharks are nocturnal.
c. the number of dolphin species is far less than the number of shark species.
d. the jawbone structure in dolphins is very different from the jawbone structure in sharks.

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.

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