1. (Z)In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow.
Which of the following, if true, most helps to explain the surprising finding?
A. Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
B. Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
C. The strength of the tidal currents in a given location varies widely over the course of a day.
D. A very large barnacle population can significantly decrease the ability of a horseshoe crab to find food.
E. Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.
2(Z)A diet high in saturated fats increases a person’s risk of developing heart disease. Regular consumption of red wine reduces that risk. Per-capita consumption of saturated fats is currently about the same in France as in the United States, but there is less heart disease there than in the United States because consumption of red wine is higher in France. The difference in regular red-wine consumption has been narrowing, but no similar convergence in heart-disease rates has occurred.
Which of the following, if true, most helps to account for the lack of convergence noted above?
A. Consumption of saturated fats is related more strongly to the growth of fatty deposits on artery walls, which reduce blood flow to the heart, than it is to heart disease directly.
B. Over the past 30 years, per-capita consumption of saturated fats has remained essentially unchanged in the United States but has increased somewhat in France.
C. Reports of the health benefits of red wine have led many people in the United States to drink red wine regularly.
D. Cigarette smoking, which can also contribute to heart disease, is only slightly more common in France than in the United States.
E. Regular consumption of red wine is declining dramatically among young adults in France, and heart disease typically does not manifest itself until middle age.
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