Night of the Living Ants
When an ant dies,other ants move the dead insect out of the nest.This behavior. is interesting to scientists,who wonder how ants know for sure-and so soon-that another ant is dead.
Dong-Hwan Choe,a scientist at the University of California,found that Argentine ants have a chemical on the outside of their bodies that signals to other ants,“I’m dead-take me away.”
But there's a twist to Choe's discovery.Choe says that the living ants-not just the dead ones -have this death chemical.In other words,while an ant crawls around,perhaps in a picnic or home,it's telling other ants that it's dead.
What keeps ants from hauling away the living dead?Choe found that Argentine ants have two additional chemicals on their bodies,and these tell nearby ants something like,“Wait-I'm not dead yet.” So Choe's research turned up two sets of chemical signals in ants:one says,“I'm dead,”the other set says,“I'm not dead yet.”
Other scientists have tried to figure out how ants know when another ant is dead.If an ant is knocked unconscious,other ants leave it alone until it wakes up.That means ants know that unmoving ants can still be alive.
Choe suspects that when an Argentine ant dies.the chemical that says“Wait-I'm not dead yet” quickly goes away.Once that chemical is gone,only the one that says“I'm dead”is left.“It's because the dead ant no longer smells like a living ant that it gets carried to the graveyard(墓地),not because its body releases new,unique chemicals after death,”said Choe.When other ants detect the“dead”chemical without the“not dead yet”chemical,they haul away the body.This was Choe's hypothesis(假设).
To test his hypothesis,Choe and his team put different chemicals on Argentine ant pupae(蛹). When the scientists used the“I'm dead”chemical,other ants quickly hauled the treated pupae away. When the scientists used the“Wait-I'm not dead yet”chemical,other ants left the treated pupae alone. Choe believes this behavior. shows that the“not dead yet”chemical overrides(优胜于)the“dead”chemical when picked up by adult ants.And that when an ant dies,the“not dead yet”chemical fades away. Other nearby ants then detect the remaining“dead”chemical and remove the body from the nest.
The phrase“this death chemical”in paragraph 3 refers to
A.the chemical that contains poison.
B.the chemical that announces death.
C.the chemical that prevents death.
D.the chemical that causes death.
第1题
A.清洁,热敷和按摩乳房可以月嫂为主进行,也可以月嫂在旁做准备、辅助和指导工作,以产妇为主进行
B.有乳头凹陷者,应特别注意乳头的清洁。
C.如果乳头发炎、乳腺发炎、乳房手术者则不能进行乳房护理
D.切忌用肥皂或酒精之类刺激较大的清洁物品,以免引起局部皮肤干燥、皲裂
第3题
产妇患有乳腺炎时喂奶前应做的护理是
A、热敷和按摩乳房
B、冷敷和按摩乳房
C、拍打乳房
D、增加婴儿吸吮的次数
E、抖动乳房
第4题
当产妇感觉乳房胀痛,错误的护理方法是()。
A哺乳前热敷乳房
B按摩乳房
C在两次哺乳的中间,冷敷乳房
D停止哺乳
第5题
A.乳房按摩前先消毒乳房
B.一只手固定乳房一侧,另一只手用大鱼际从乳房边缘向乳头中心做环形按摩
C.知道产妇佩戴宽松乳罩
D.按摩时,必须根据产妇的感觉进行
E.乳房按摩前先清洁乳房
第7题
A.乳房按摩前先消毒乳房
B. 一只手固定乳房一侧,另一只手用大鱼际从乳房边缘向乳头中心做环形按摩
C. 知道产妇佩戴宽松乳罩
D. 按摩时,必须根据产妇的感觉进行
E. 乳房按摩前先清洁乳房
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