Suppose that during a detailed anatomical study of a marine invertebrate, you found a small, previously undescribed structure. How would you test the hypothesis that the structure is a gland that releases one or more hormones?

DRAW IT In mammals, milk production by mammary glands is controlled by prolactin and prolactin-releasing hormone. Draw a simple sketch of this pathway, including glands, tissues, hormones, routes for hormone movement, and effects.

Which two of the hormones listed below act upon the body with similar functions? Explain. a. glucagon b. oxytocin c. glucocorticoids d. ADH

Design a study to test the hypothesis that the symptoms of jet lag are caused by disruption of normal daily cortisol rhythms.

A strain of mice remains healthy as long as they are fed regularly. After they eat, their blood glucose level rises slightly and then declines to a homeostatic level. However, when these mice fast or exercise, their blood glucose drops dangerously. Which hypothesis best explains their problem? (Explain your choice.) a. The mice have insulin-dependent diabetes. b. The mice lack insulin receptors on their cells. c. The mice lack glucagon receptors on their cells. d. The mice cannot synthesize glycogen from glucose.

SCIENTIFIC THINKING The results of Tyrone Hayes's experiments (Module 26.3) were published in a top peer-reviewed journal, yet the validity of his experiments has since been challenged. Using external sources, find out who has challenged the results.

Scientists set out to test the hypothesis that the herbicide atrazine is an endocrine disruptor that feminizes male amphibians. They treated male amphibians with atrazine and then compared their circulating testosterone concentration with those of males and females that were not treated with atrazine (controls). The results are shown here (* signifies P<0.05). Was the hypothesis supported? Why or why not?

Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world's largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins' ability to respond to stressors? Has it affected the penguins' secretion of corticosterone?Corticosterone is a(n):a. neurohormoneb. steroid hormonec. amino-acid-derived hormoned. polypeptide hormone

Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world's largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins' ability to respond to stressors? Has it affected the penguins' secretion of corticosterone?In what part(s) of a target cell would you expect to find corticosterone receptors?