Endocrine glands secrete hormones over a membrane into the bloodstream.
Explanation:
The endocrine glands are characterized by the secretion of hormones that pass directly into the bloodstream. This is because, unlike the exocrine glands, they do not have ducts.
Hormones leave the endocrine cell through transmembrane transport, to reach the blood capillaries and from there to the general circulation.Once the hormones are released into the bloodstream they bind to specific effector cells, attaching to membrane receptors for these substances.
I'm not sure about the donkey kong one but for the dog food one they see the reactions of dogs. They might have a human tester but i'm pretty sure no one would think dog food is good.