Nature is full of color, from rainbows and roses to butterfly wings and peacock tails. Even the fruits and vegetables you eat have different colors: blue blueberries, red strawberries, green broccoli, and orange carrots.
Plant and animals often use color to attract attention. The substances responsible for these colors belong to a class of chemical called antioxidants(抗氧化物). Plants make antioxidant to protect themselves from the sun’s ultraviolet(UV)(紫外线)light.
Ultraviolet light causes chemicals called free radicals(自由基)to form within plant cells. They can destroy parts of plant. Free radicals also have damaging effects on human beings. Some of these effects like wrinkled skin can be seen. The damage is caused by the free radicals attacking cells in our bodies. Certain cancers and heart disease are linked to free radicals.
Our bodies have natural defences for fighting off free radicals. While we are young, our defences are pretty strong. However, they get weaker as we get older. The body’s built-in defences can only go so far without extra help.
The key to fighting free radicals with fruits and vegetables is to mix and match colors. It’s like sunscreen(防晒霜)for the inside of your body. Go for a range of very bright colors. Colorful foods contain hundreds of healthy chemicals not found anywhere else.
Research into how chemicals in blueberries affect the brain’s function in rats suggests that these chemicals may help our own brains work more efficiently.
Don’t just blame the sun. Ultraviolet light isn’t the only source of free radicals. If you breathe polluted air such as smog, automobile exhaust(废气), or wasted gas from a factory, you take in chemicals that also cause such damage. And, the body itself produces free radicals as it processes food.
【小题1】Which of the following not true?A．Antioxidants are responsible for plant colorsB．Plants use color to attract attentionC．Antioxidants can protect plants from UV lightD．Antioxidants help free radicals to attack plants【小题2】In which order do the following facts occur?
a Wrinkled skin can be seen
b UV light causes free radicals to form
c Free radicals damage cells in our bodies
d The sun gives out UV lightA．a,b,c,dB．d,b,c,aC．c,a,d,bD．d,b,a,c【小题3】We need extra help for fighting off free radicals from fruits and vegetables because .A．our bodies’ defences are not naturalB．we are too young to defend ourselvesC．our defences get weaker as we get olderD．our bodies’ built-in defences can only go away【小题4】Which of the following can not cause free radicals to form?A．Colorful foodB．UV light from the sunC．Polluted airD．The body itselfD
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(答案→)D
解析：这篇文章讲述了太阳的紫外线、烟雾、汽车的排气、工厂的废气等都可造成自由基的生成，自由基会破坏人体细胞，各种颜色的食物是帮助我们抗自由基的有效方法。
【小题1】根据Plant and animals often use color to attract attention. The substances responsible for these colors belong to a class of chemical called antioxidants(抗氧化物). Plants make antioxidant to protect themselves from the sun’s ultraviolet(UV)(紫外线)light.排除A、B和C，故选D。
【小题2】事情发生的先后顺序是：先是太阳释放出紫外线，然后紫外线造成自由基的生成，接着自由基破坏我们身体的细胞，最后皮肤起皱纹，故选B。
【小题3】根据However, they get weaker as we get older. The body’s built-in defences can only go so far without extra help.所以答案为C。
【小题4】各种颜色的食物是帮助我们抗自由基的，因此选A。