题型：阅读理解 题类：常考题 难易度：普通
福建省龙岩市2020届高三下学期英语5月教学质量检查试卷
A butterfly's wings can have many jobs besides keeping the insect in the air. They may be called on to attract mates, to warn potential enemies to stay away, to do other animals or even to provide disguise(伪装).
All of these roles, though, depend on their colouration-which is unchanging. This plays into the idea that butterfly wings are dead tissue, like a bird's feathers or a mammal's hair. In fact, that is not true. For example, in some species males' wings harbour special cells that release chemicals which attract females.
Nanfang Yu, a physicist at Columbia University, in New York, has been looking into the matter. One of his interests is the optical (光学的) properties of biological materials. That has led him to study butterfly wings in more detail. And, in cooperation with Naomi Pierce, a butterfly specialist at Harvard University, he has now shown, in a paper published this week in Nature Communications, that butterfly wings are, indeed, very much alive.
Initially, Dr Yu and Dr Pierce wanted to know how the insects keep their body temperatures up without their wings overheating. Unlike birds and mammals, butterflies do not produce enough internal heat to metabolize(新陈代谢). Instead, they rely on outside heat sources-usually the sun-to bring their bodies up to speed. But their wings, being thin protein membranes (膜), have a limited thermal capacity. Those wings can therefore overheat quickly if the insects are exposed to the sunlight too long, or, oppositely, can cool down too rapidly if they are flying through cold air.
In their experiments, the two researchers used a laser (激光) to heat up spots on the wings of dozens of butterfly species. When the temperature of the area under the laser reached 40℃ or so, the insects responded within seconds by doing things that stopped their wings heating up further. These actions included a butterfly turning around to minimize its exposure to the laser, beating its wings or simply walking away.
试题篮
