22. Why were African bees considered beneficial? (A) They produced as unusual type of honey. (B) They spent their time traveling. (C) They were very aggressive. (D) They hid from inclement weather.

1955. The African bees were brought into Brazil because their aggression was considered an advantage: they were far more productive than their European counterparts in that they spent a higher percentage of their time working and continued working longer in inclement weather than did the European bees. These killer bees have been known to attack humans and animals, and some fatalities have occurred. Experts point out, however，that the mixed breed known as the killer bee is actually not at all as aggressive as the pure African bee. They also point out that the attacks have a chemical cause. A killer bee stings only when it has been disturbed; it is not aggressive by nature. However, after a disturbed bee stings and flies away，it leaves its stinger embedded in the victim. In the vicera attached to the embedded stinger is the chemical isoamy夏 acetate， which has an odor that attracts other bees. As other bees approach the victim of the original sting, the victim tends to panic, thus disturbing other bees and causing them to sting. The new stings create more of the chemical isoamyl acetate, which attracts more bees and increases the panic level of the victim. Killer bees tend to travel in large clusters or swarms and thus respond in large numbers to the production of isoamyl acetate.

題組內容

22. Why were African bees considered beneficial? (A) They produced as unusual type of honey. (B) They spent their time traveling. (C) They were very aggressive. (D) They hid from inclement weather.

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