Unit 1 Art reading课时作业

阅读理解

　　A

　　(2017·全国卷Ⅱ)When a leafy plant is under attack，it doesn't sit quietly. Back in 1983，two scientists，Jack Schultz and Ian Baldwin，reported that young maple trees getting bitten by insects send out a particular smell that neighboring plants can get. These chemicals come from the injured parts of the plant and seem to be an alarm.What the plants pump through the air is a mixture of chemicals known as volatile organic compounds，VOCs for short.

　　Scientists have found that all kinds of plants give out VOCs when being attacked .It's a plant's way of crying out.But is anyone listening？Apparently.Because we can watch the neighbours react.

　　Some plants pump out smelly chemicals to keep insects away.But others do double duty .They pump out perfumes designed to attract different insects who are natural enemies to the attackers. Once they arrive, the_tables_are_turned.The attacker who was lunching now becomes lunch.

　　In study after study，it appears that these chemical conversations help the neighbors .The damage is usually more serious on the first plant，but the neighbors, relatively speaking ，stay safer because they heard the alarm and knew what to do.

Does this mean that plants talk to each other? Scientists don't know. Maybe the first plant just made a cry of pain or was sending a message to its own branches, and so, in effect, was talking to itself. Perhaps the neighbors just happened to "overhear" the cry. So information was exchanged, but it wasn't a true, intentional back and forth.