The excessive number of safety regulations that the federal government has placed on indus

that in a free society people have the right to take risks as long as the people do not harm others as a result of taking the risks. As a result, they conclude that it should be each person s decision whether or not to wear a seat belt. Which of the following, if true, most seriously weakens the conclusion drawn above?

A．Many new cars are built with seat belts that automatically fasten when someone sits in the front seat.

B．Automobile insurance rates for all automobile owners are higher because of the need to pay for the increased injuries or deaths of people not wearing seat belts.

C．Passengers in airplanes are required to wear seat belts during takeoffs and landings.

D．The rate of automobile fatalities in states that do not have mandatory seat-belt laws is greater than the rate of fatalities in states that do have such laws.

E．In automobile accidents, a greater number of passengers who do not wear seat belts are injured than are passengers who do wear seat belts.

status. Even though in some localities in the United vStates the rate is higher than in many developing countries, in the United States overall the rate has been steadily declining. This decline does not necessarily indicate, however, that babies in the United States are now, on the average, healthier at birth than they were in the past. Which one of the following reasons, if true, most strongly supports the claim made above about the implications of the decline?

A．The figure for infant mortality is compiled as an overall rate and thus masks deficiencies in particular localities.

B．Low birth weight is a contributing factor in more than half of the infant deaths in the United States.

C．The United States has been developing and has achieved extremely sophisticated technology for saving premature and low-birth-weight babies, most of whom require extended hospital stays.

D．In eleven states of the United States, the infant mortality rate declined last year.

E．Babies who do not receive adequate attention from a caregiver fail to thrive and so they gain weight slowly.

pproaching extinction on the South Island. But since South Island tuatara were thought to be of the same species as North Island tuatara there was no need to protect them. But new research indicates that the South Island tuatara are a distinct species, found only in that location. Because it is now known that if the South Island tuatara are lost an entire species will thereby be lost, human beings are now obliged to prevent their extinction, even if it means killing many of their unendangered natural predators. Which one of the following principles most helps to justify the naturalists argumentation?

A．In order to maximize the number of living things on Earth, steps should be taken to preserve all local populations of animals.

B．When an animal is in danger of dying, there is an obligation to help save its life, if doing so would not interfere with the health or well-being of other animals or people.

C．The threat of local extinction imposes no obligation to try to prevent that extinction, whereas the threat of global extinction does impose such an obligation.

D．Human activities that either intentionally or unintentionally threaten the survival of an animal species ought to be curtailed.

E．Species that are found in only one circumscribed geographical region ought to be given more care and attention than are other species because they are more vulnerable to extinction.

able trash. Flan 1—Residents will deposit recyclable trash in municipal dumpsters located in the parking lot. The trash will be collected on the first and the fifteenth days of each month. Plan 2—Residents will be given individual containers for recyclable trash. The containers will be placed at the curb twice a week for trash collection. Which of the following points raised at a meeting of the residents, if valid, would most favor one of the recycling plans over the other?

A.Residents will be required to exercise care in separating recyclable trash from nonrecyclable trash.

B.For trash recycling to be successful, residents must separate recyclable bottles and cans from recyclable paper products.

C.Penalties will be levied against residents who fail to sort their trash correctly.

D.Individual recycling containers will need to be made of a strong and durable material.

E.Recyclable trash that is allowed to accumulate for two weeks will attract rodents.

tage of this increase, Mammoth Industries plans to expand production of its own model of telephone, while continuing its already very extensive advertising of this product. Which of the following, if true, provides most support for the view that Mammoth Industries cannot increase its sales of telephones by adopting the plan outlined above?

A．Although it sells all of the telephones that it produces, Mammoth Industries" share of all telephone sales has declined over the last year.

B．Mammoth Industries" average inventory of telephones awaiting shipment to retailers has declined slightly over the last year.

C．Advertising has made the brand name of Mammoth Industries" telephones widely known, but few consumers know that Mammoth industries owns this brand.

D．Mammoth Industries" telephone is one of the three brands of telephone that have together accounted for the bulk of the last year"s increase in sales.

E．Despite a slight decline in the retail price, sales of Mammoth Industries" telephones have fallen in the last year.

ief that

A．the space between the galaxies is devoid of matter.

B．the space between galaxies is occupied by stars that cannot be detected by optical photographs.

C．galaxies have decreased in mass by half since their formation.

D．galaxies contain stars, each the size of Jupiter, which form. clusters.

E．galaxies are being penetrated by gas forced out of other galaxies by supernova explosions.

the British colonists

A．collected tribute from the native population.

B．kept records from a very early date.

C．drove Native Americans off the land.

D．were unable to provide medical care against epidemic disease.

E．enslaved the native populations in America.

iversity of Virginia lectures in 1954?

A．Southern racial segregation was continuous and uniform.

B．Black people made considerable progress only after Reconstruction.

C．Jim Crow legislation was conventional in nature.

D．Jim Crow laws did not go as far in codifying traditional practice as they might have.

E．Jim Crow laws did much more than merely reinforce a tradition of segregation.

e a potential source of aid to a patient who was not adequately producing and releasing serotonin?

A．Meals consisting almost exclusively of protein.

B．Meals consisting almost exclusively of carbohydrates.

C．Meals that would elicit insulin secretion.

D．Meals that had very low concentrations of tyrosine.

E．Meals that had very low concentrations of leucine.

here in the body. In recent studies, however, we have discov- ered that the production and release in brain neurons of the neurotransmitter serotonin(neurotransmitters are compounds that neurons use to transmit signals to other cells)depend directly on the food that the body processes. Our first studies sought to determine whether the increase in serotonin observed in rats given a large injection of the amino acid tryptophan might also occur after rats ate meals that change tryptophan levels in the blood. We found that, immediately after the rats began to eat, parallel elevations occurred in blood tryptophan, brain tryptophan, and brain serotonin levels. These findings suggested that the production and release of serotonin in brain neurons were normally coupled with blood-tryp-tophan increases. In later studies we found that injecting insulin into a rats bloodstream also caused parallel elevations in blood and brain tryptophan levels and in serotonin levels. We then decided to see whether the secretion of the animals own insulin similarly affected serotonin production. We gave the rats a carbohydrate-containing meal that we knew would elicit insulin secretion. As we had hypothesized, the blood trypto- phan level and the concentrations of tryptophan serotonin in the brain increased after the meal. Surprisingly, however, when we added a large amount of protein to the meal, brain tryptophan and serotonin levels fell. Since protein contains tryptophan, why should it depress brain tryptophan levels? The answer lies in the mechanism that provides blood tryp- tophan to the brain cells. This same mechanism also provides the brain cells with other amino acids found in protein, such as tyrosine and leucine. The consumption of protein increases blood con- centration of the other amino acids much more, proportionately, than it does that of tryptophan. The more protein in the meal, the lower is the ratio of the resulting blood-tryptophan concentration to the concentration of competing amino acids, and the more slowly is tryptophan provided to the brain. Thus the more protein in a meal, the less serotonin subsequently produced and re- leased.

Which of the following titles best summarizes the contents of the passage?

A．Neurotransmitters: Their Crucial Function in Cellular Communication

B．Diet and Survival: An Old Relationship Reexamined

C．The Blood Supply and the Brain: A Reciprocal Dependence

D．Amino Acids and Neurotransmitters: The Connection Between Serotonin Levels and Tyrosine

E．The Effects of Food Intake on the Production and Release of Serotonin: Some Recent Findings