2. 外语
  3. COGNITIVE MAPS IN ANIMALS (1) A central hypothesis of animal cognition is that many animals make use of cognitive maps—inter

COGNITIVE MAPS IN ANIMALS (1) A central hypothesis of animal cognition is that many animals make use of cognitive maps—inter

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问题                                             COGNITIVE MAPS IN ANIMALS
    (1) A central hypothesis of animal cognition is that many animals make use of cognitive maps—internal representations or codes—of the spatial relationships among objects in their surroundings. In a broad sense, most animals that migrate probably have some internal map of the way external objects are arranged.
    (2) The most extensive studies of cognitive maps have been made for animals that exhibit seasonal migration, the regular back-and-forth movement of animals between two geographic areas at particular times of the year. [A] Seasonal migration enables many species to access rich food resources throughout the year and to breed or winter in areas that favor survival. [B] One long-distance traveler is the gray whale. [0] During summer, these giant aquatic mammals feast on small, bottom-dwelling invertebrates that abound in northern oceans. [D] In the fall, they leave their northern feeding grounds and begin a long trip south along the North American coastline. Arriving in warm, shallow lagoons off Baja California (Mexico) in the winter months, they breed, and pregnant females give birth to young before migrating back north. The yearly round-trip, some 20,000 kilometers, is the longest for any mammal.
    (3) Among insects, the monarch butterfly has one of the most remarkable seasonal migrations. During winter, these insects decorate certain trees at the western tip of Cuba, in a few mountain valleys of central Mexico, and at a few sites along the California coast. All monarchs alive at the end of summer fly south to reach their wintering sites. With the onset of spring, monarchs mate at the wintering sites and begin migrating northward. As they arrive at summer destinations, they lay eggs and then die. Two or more generations are produced during the summer, repopulating the United States and southern Canada. With the approach of fall, the summer’s last generation of monarchs flies south to the wintering grounds. They migrate as far as 4,000 kilometers and end up at a specific site, although they have not flown the route before.
    (4) Researchers have found that migrating animals stay on course by using a variety of environmental cues. Gray whales, for instance, seem to use coastal landmarks to pilot their way north and south. Migrating south in the fall, they orient themselves with the North American coastline on their left. Migrating north in the spring, they keep the coast on their right. Whale watchers sometimes see gray whales stick their heads straight up out of the water, perhaps to obtain a visual fix on land. Many birds migrate at night, navigating by the stars the way ancient human soldiers did. In contrast, monarch butterflies migrate during the day, resting in trees and bushes at night; genetic programming may enable them to use the Sun as a compass.
    (5) Navigating by the Sun or by stars requires an ability to keep track of compass direction. Many migrators also must have an internal timing mechanism that compensates for the continuous daily movement of Earth relative to celestial objects. The timing mechanism must also allow for the apparent change in position of celestial objects as the animal moves over its migration route. Almost nothing is known yet about the nature of these timing mechanisms. At least one night-migrating bird, the indigo bunting, seems to avoid the need for a timing mechanism by fixing on the North Star, the one bright star in northern skies that appears almost stationary. Researchers have found that buntings learn a star map and fix on a stationary star when navigating at night.
     (6) Another interesting, and more or less open, question about migration is how birds continue navigating when the Sun or stars are obscured by clouds. There is strong evidence that some birds can orient themselves to Earth’s magnetic field. Magnetite, the iron-containing mineral once used by sailors as a crude compass, is probably involved in sensing the field. The mineral has been found in the heads of pigeons, in the abdomens of bees, and in certain bacteria that orient themselves to a magnetic field. Future research may show that magnetic sensing is a widespread, important part of a complex navigation mechanism in many animals.
The discussion of bird migration in paragraph 6 implies that________.
选项 A、birds that can navigate by sensing Earth’s magnetic field cannot navigate using the Sun or stars
B、pigeons can navigate when the Sun or stars are obscured by clouds
C、magnetite is likely to be part of the navigational system of only a few species of birds
D、birds’ navigation using magnetite is not as accurate as their navigation based on the Sun or stars
答案B
解析 本题属于推论题，问第6段关于鸟类迁徙的讨论暗示了什么：第6段主要讨论鸟类在太阳和星辰被云层遮挡时靠什么继续导航。综合第2句可知，有些鸟类靠地球磁场导航，且在鸽子的头部、蜜蜂的腹部和根据磁场来定位的某些细菌中，都发现了磁铁矿这种可用于感应磁场的天然指南针。由此可知，当太阳或星辰被云层遮蔽以后，鸽子也能够继续航行(即B项)。A项“通过感知地球磁场来导航的鸟类不能利用太阳或星辰来导航”和D项“鸟类利用磁铁矿来导航没有利用太阳或星辰导航那么精确”在第6段中均无法找到支撑依据。C项“磁铁矿很可能仅是少数鸟类导航系统的一部分”与第6段倒数两句的表述不相符。
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