Objective
To use transitions and thought patterns to identify the supporting details and main ideas in a textbook selection.

Step 2: Read the following selection from a college biology textbook, and answer the questions that follow it.

Case Study Revisited

     As you have seen, human cells most efficiently extract energy from glucose when an ample supply of oxygen is available to them. The aim of blood-doping cyclists, then, is to extend as long as possible the period in which their muscle cells have access to oxygen. During a difficult hillclimb, a cyclist who has doped his blood with erythropoietin may be able to pedal efficiently, his muscle cells using the Krebs cycle to turn out abundant ATP. At the same time, his "clean" competitor may labor painfully, leg muscles laden with lactate from fermentation.
     The extra endurance that EPO supplies can tempt elite athletes to risk their health for an extra edge, despite the penalties that await those who are caught using a banned substance. The temptation may be especially large in the case of EPO. Because this substance forms naturally in the human body, its abuse is hard to detect; standard drug-screening procedures cannot distinguish between natural EPO and that injected in blood doping. In fact, the Festina team that was banned from the 1998 Tour de France was caught not by any blood or urine test, but only because a large supply of EPO was found in the team's car at a border crossing.
     Since the Festina fiasco, however, researchers have worked hard at developing better tests for blood doping with EPO. A new urine test for EPO was introduced at the 2000 summer Olympics. This test detects a subtle chemical difference between the breakdown products of natural EPO and those of the manufactured version that is used in doping injections. Olympic officials, however, are not totally confident in the accuracy of the new urine test, and they use it only in conjunction with blood tests that screen for unusually high density of blood cells. Only athletes who fail both tests are disqualified. Meanwhile, researchers continue to explore the chemistry of EPO metabolism in hope of discovering a definitive test for blood doping.

—Audesirk, Audesirk, and Byers, Life on Earth, 3rd ed., p.104

		6. What must be present so that human cells can extract energy from glucose?    a. ATP   b. EPO   c. ample oxygen   d. carbon dioxide
		7. The aim of blood doping is     a. to extend as long as possible the period in which an athlete's muscle cells have access to oxygen.   b. to rid muscles of excess oxygen to make them more efficient.   c. to slow down the circulation so that extra stress is not put on the heart.   d. to outperform competitors by reducing the amount of oxygen in the blood.
		8. The reason blood doping is so difficult to detect is that    a. the substance dissipates so quickly in cyclists.   b. the substance forms naturally in the body and standard drug-screening procedures cannot distinguish clearly between natural and injected substances.   c. EPO is impossible to detect.   d. health insurance companies will not pay for such testing, and it is very expensive.
		9. The transition word in this selection that indicates a cause-and-effect pattern is     a. because.   b. however.   c. during.   d. at the same time.
		10. What resulted in the Festina team being banned from the 1998 Tour de France?    a. The riders failed the new urine test that had just been introduced.   b. The riders were caught selling EPO to other cyclists on competing teams.   c. A large supply of EPO was found in the team's car at a border crossing.   d. Some of the riders failed the blood test.