11. Which of the following is true about a hydrophilic signaling molecule?

A. Its receptor is located in the cytosol of the target cell
B. It might trigger a signal cascade that causes some effect in a cell
C. Since it can enter the cell, it directly affects some specific cell process
D. It is a steroid

12. cAMP and cGMP are derived from

A. ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively
B. GTP and ATP by the actions of adenylate cyclase and guanylate cyclase respectively
C. ATP and GTP by the actions of guanylate cyclase and adenylate cyclase respectively
D. none of the above

13. Nitroglycerin has long been administered to human patients suffering from chronic chest pain (angina). This medication works because it

A. mimics the action of signal receptors
B. is broken down into hormones that affect the heart
C. interferes with chemical cascades that trigger contraction of heart muscle
D. breaks down into nitric oxide, which increases blood flow to the heart

14. If a disease of the blood vessels caused the endothelial cells of the vessel to die, what effect would that have on the cellular activities associated with vasodilation?

A. Nitric oxide would no longer be produced
B. Smooth muscle cells could not be made to relax
C. It would be more difficult to increase blood flow and reduce blood pressure
D. All of the above

15. In terms of cell communication, what do bacterial pathogens such as cholera and anthrax have in common?

A. They destroy the receptors for key signaling molecules
B. They prevent the production of key signaling molecules
C. They alter the chemical structure of key signaling molecules
D. They block the normal functioning of signal transduction mechanisms