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【简答题】

Plants can’t communicate by moving or sounds, as most animals do. Instead, plants produce volatile compounds (挥发性化合物) —— chemicals that easily change from a liquid to a gas. A flower’s sweet smell, for example, comes from such volatile compounds to attract insects such as bugs and bees. Plants can also discover volatile compounds produced by other plants. A tree under attack by hungry insets, for instance, may give off these chemicals in order to let other trees know about the attack. In response, the other trees may send off their chemicals to keep the bugs away —— or even chemicals that will attract the bugs’ natural enemies. Now scientists have created a quick way to understand what plants are saying: a chemical sensor (传感器) called an “electronic nose”. The “e-nose” can tell such compounds as plants make. When plants are attacked, scientists say, the e-nose could help quickly decide whether plants are being eaten by insects. But today, the only way to spot such insects is to inspect individual plants by observing them. This is a challenging task for managers of greenhouses, including those that can house thousands of plants. The research team is working with an e-nose that can recognize volatile compounds. Inside the device, 13 sensors chemically react with volatile compounds based on the interactions (相互作用), and then the e-nose will give off electronic signals that the scientists can yze by using computer software. To test the e-nose, the team presented it with healthy leaves from cucumber, pepper and tomato plants, all being common greenhouse crops. Then scientists collected samples of the air around damaged leaves from each type of crop. These plants had been damaged either by insects or by scientists who made holes in the leaves with a hole punch (打孔器). The e-nose, it turns out, can identify healthy cucumber, pepper and tomato plants based on the volatile compounds they produce. It could also identify tomato leaves that had been damaged. But even more impressive, the device could tell which type of damage —— by insects or with a hole punch —— had been done to the tomato leaves. With some fine-tuning (微调), a device like the e-nose can one day be used in greenhouses to quickly spot harmful bugs, the researchers say. A device like this can also be used to identify fruits that are perfectly ripe and ready to pick and eat, says Natalia Dudareva, a biochemist at Purdue University in West Lafayette, India, who studies smells of flowers and plants. Hopefully, scientists believe, the device can bring large benefits to greenhouse managers in the near future. 小题1:We learn from the text that plants communicate with each other by ______. A. some sounds B.waving their leaves C.producing some chemicals D.sending out electronic signals 小题2:What did the scientists do to find out if the e-nose worked? A.They fixed 13 sensors inside the device. B.They presented it with all common crops. C.They collected different damaged leaves. D.They do tests on damaged and healthy leaves. 小题3:According to the writer, the most amazing thing about the e-nose is that it can ______. A.pick out ripe fruits quite expertly B.spot the insects in a very quick way C.tell different damages to leaves D.recognize unhealthy tomato leaves 小题4:We can infer from the last paragraph that the e-nose ______. A.is unable to tell the smell of flowers B.is not yet tested in greenhouses C.is designed by scientists at Purdue D.is helpful in killing harmful insects

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举一反三

【单选题】下列有关铁及其化合物的有关说法中正确的是(  )

A.
赤铁矿的主要成分是Fe3O4
B.
铁与水蒸气在高温下的反应产物为Fe2O3和H2
C.
除去FeCl2溶液中的FeCl3杂质可以向溶液中加入铁粉,然后过滤
D.
Fe3+与KSCN产生血红色沉淀

【单选题】拟建项目与环境之间的相互作用关系是()。

A.
[拟建项目]+[环境]→(变化的环境)
B.
[拟建项目]+[活动]→(变化的环境)
C.
[拟建项目]+[环境]→(活动)
D.
[拟建项目]+[要素]→(变化的环境)

【单选题】全麻药对脂质膜的相互作用,哪项是正确的()

A.
膜通透性增加及进入膜内水分增加
B.
膜容积增加,通道受挤压
C.
外界压力增加时细胞膜的侧向压力增加,促进通道关闭
D.
温度升高使膜容积增加
E.
使跨膜电场发生改变并使离子经通道流到膜外