Question

    If you were bringing friends home to visit, you could show them the way. You know the landmarks—a big red house or a bus-stop sign. But what if you were swimming in the middle of the Atlantic Ocean? Could you still find your way home? A loggerhead turtle（海 龟）could.

According to Dr. Ken Lohmann, loggerheads have a magnetic（磁力的）sense based on Earth’s magnetic field. It helps them locate the best spots for finding food and their home beaches.

Scientists already know that several other animals, such as whales and honeybees, can detect（探测到）magnetic fields. The difference between them and loggerheads, however, is the way they learn to use their magnetic sense. Young whales and honeybees can learn from adults. Loggerheads are abandoned as eggs.

As newborn loggerheads have no adults to learn from, what helps them figure out how to use their magnetic sense? Lohmann thinks one of the cues was light on the sea.

Baby loggerheads hatch only at night. However, a small amount of light reflects off the ocean. The light makes that region brighter. Heading toward the light helps them get quickly out to sea, where they can find food. Lohmann tested whether newborn loggerheads use this light source to set their magnetic “compasses”（罗盘）. He and his team put some newborns in a water tank and recorded which way they swam. Around the tank, the scientists created a magnetic field that matched the Earth’s. They set a weak light to the east of the magnetic field. Then they let the newborns go.

At first, the newborns swam toward the light. After the scientists turned off the light, the turtles that had seen the light in the east always swam toward east. When the researchers reversed（颠倒）the magnetic field, these turtles turned around and swam toward the new “east”.

This and the follow-up experiments all showed that loggerheads use light from the outside world to set their magnetic “compasses” and then remember the “correct” direction. If a turtle hatches on a brightly-lit beach, that would damage its magnetic sense forever and make survival hard for the turtle.

Lohmann’s work has led others to protect the habitat of this endangered species. Yet many questions about these creatures remain unanswered, and researchers have a lot to study.

1.Loggerheads and whales differ in the way they______.

A.bring up their young

B.recognize landmarks

C.detect magnetic fields

D.learn to find directions

2.What is needed for newborn loggerheads to set their magnetic sense?

A.Weak light reflected off the ocean. B.Help from adult loggerheads.

C.Bright sunlight from the sky. D.Food in warmer waters.

3.In the experiment, after the newborns’ magnetic sense was set, their moving direction was determined by ____.

A.the light

B.the magnetic field

C.other unknown factors

D.the light and the magnetic field

4.What is the significance of Lohmann’s research work?

A.It enables researchers to keep track of turtles.

B.It contributes to the studies of the magnetic field.

C.It offers a new solution to environmental pollution.

D.It helps protect the loggerheads’ living environment.

5.What could be the best title of the passage?

A.Experiments on Loggerheads

B.The Survival of the Sea Turtle

C.The Loggerhead’s Built-in “Compass”

D.Comparison of Loggerheads and Other Animals

Answer

1.D

2.A

3.B

4.D

5.C

【解析】

这是一篇说明文。短文介绍了红海龟与其它很多动物一样都可以感知磁场。与其它动物感知磁场不同的是，海龟依靠光来感知磁场。

1.细节理解题。由第三段“The difference between them and loggerheads, however, is the way they learn to use their magnetic sense.”可知，然而，它们和红海龟之间的区别在于它们学会使用磁感应的方式。所以红海龟和鲸鱼的区别在于它们学习寻找方向的方式。故选D项。

2.细节理解题。由第五段“Baby loggerheads hatch only at night. However, a small amount of light reflects off the ocean. The light makes that region brighter. Heading toward the light helps them get quickly out to sea, where they can find food”可知，小红海龟只在晚上孵化。然而，微弱的光反射到海洋上。光线使那个区域更亮。朝着光走有助于它们迅速到达大海，在那里它们可以找到食物。所以微弱的光反射到海洋上，来帮助设定他们的磁场感应。故选A项。

3.细节理解题。由倒数第三段“At first, the newborns swam toward the light. After the scientists turned off the light, the turtles that had seen the light in the east always swam toward east. When the researchers reversed（颠倒）the magnetic field, these turtles turned around and swam toward the new “east””可知，刚开始，新出生的小海龟向光游去。科学家们把灯关掉后，看到了东方有光的海龟总是向着东方游动。当研究者颠倒磁场当研究员颠倒磁场之后， 这些海龟调转方向， 向着新的“东方”游去。所以实验中，新生儿磁感建立后，其运动方向由磁场决定。故选B项。

4.细节理解题。由最后一段“Lohmann’s work has led others to protect the habitat of this endangered species”可知，Lohmann的研究使得其他人保护这种濒危物种的栖息地。所以Lohmann研究工作的意义在于它有助于保护红海龟的生存环境。故选D项。

5.主旨大意题。通过读全文可知，海龟与其它很多动物一样都可以感知磁场。与其它动物感知磁场不同的是，海龟依靠光来感知磁场。所以短文最佳标题为“红海龟的内置“指南针”。故选C项。