PTE Multiple Choice, Single Answer Practice

Although the hormone adrenaline is known to regulate memory storage, it does not pass from the blood into brain cells. This presents an apparent paradox: how can a hormone that does not act directly on the brain have such a significant effect on brain function? Recently, we tested the possibility that one of the hormone’s actions outside the brain might be responsible. Since one consequence of adrenaline release in an animal is an increase in blood glucose levels, we examined the effects of glucose on memory in rats. We found that glucose injected immediately after training enhances memory tested the next day. Additional evidence was provided by negative findings: drugs called adrenergic antagonists, which block peripheral adrenaline receptors, disrupted adrenaline’s ability to regulate memory but did not affect memory enhancements produced by glucose that was not stimulated by adrenaline. These results align with the hypothesis that adrenaline affects memory modulation by increasing blood glucose levels.

One explanation for the tendency of animals to be more vigilant in smaller groups than in larger ones assumes that vigilant behavior—such as looking up—is directed at predators. If individuals on the edge of a group are more vigilant because they are at greater risk of being captured, then individuals, on average, would need to be more vigilant in smaller groups. This is because animals on the periphery make up a larger proportion of the group as the group size decreases. However, a different explanation is needed in cases where vigilant behavior is not directed at predators. J. Krebs discovered that great blue herons look up more frequently in smaller flocks than in larger ones solely due to poor feeding conditions. Krebs hypothesizes that herons in smaller flocks are watching for other herons they might follow to better feeding pools, which typically attract larger numbers of birds.

Communication skills essentially involve the ability to convey your message clearly and effectively, both orally (for example, in meetings) and in writing (such as in reports and records). Unfortunately, both of these areas have been undervalued in the past and have not received the attention they deserve in terms of training and development. Therefore, it is important to ensure that we do not appear unprofessional in meetings due to a lack of presentation skills, and that we do not neglect records and reports because we feel unconfident in writing them effectively or fail to recognize their significance. Many disastrous mistakes have occurred because of poor or non-existent written communication.

The outpouring of contemporary American Indian literature in the last two decades, often called the Native American Renaissance, represents for many the first opportunity to experience Native American poetry. The appreciation of traditional oral American Indian literature has been limited, hampered by poor translations and by the difficulty, even in the rare culturally sensitive and aesthetically satisfying translation, of completely conveying the original’s verse structure, tone, and syntax. By writing in English and experimenting with European literary forms, contemporary American Indian writers have broadened their potential audience while clearly retaining many essential characteristics of their ancestral oral traditions. For example, Pulitzer Prize-winning author N. Scott Momaday’s poetry often treats art and mortality in a manner that recalls British romantic poetry, while his poetic response to the power of natural forces recalls Cherokee oral literature. Similarly, his novels, an art form European in origin, display an eloquence that echoes the oratorical grandeur of the great nineteenth-century American Indian chiefs.

Recently, some scientists have concluded that meteorites found on Earth, long believed to have a Martian origin, might actually have been blasted free of Mars’s gravity by the impact of other meteorites on Mars. This conclusion has raised another question: whether meteorite impacts on Earth have similarly propelled rocks from this planet to Mars. According to astronomer S. A. Phinney, freeing a rock from Earth’s gravity would require a meteorite capable of creating a crater over 60 miles in diameter. Furthermore, even if Earth rocks were ejected by meteorite impacts, Mars’s orbit is much larger than Earth’s. Phinney estimates that the probability of these rocks hitting Mars is about one-tenth the probability of Martian rocks hitting Earth. To illustrate this estimate, Phinney used a computer simulation to calculate where 1,000 hypothetical particles ejected from Earth in random directions would end up. The simulation revealed that 17 of the 1,000 particles would strike Mars.