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. These ants are
a little bit like zombies (僵尸). Choe says that the living ants—not just the dead
ones—have this death chemicals. 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" chemicals, other ants left the treated pupae alone. Choe
believes this behavior shows that the "not dead yet" chemicals override (优先于)
the "dead" chemical when picked up by adult ants. And that when an ant dies, the
"not dead yet" chemicals fade away. Other nearby ants then detect the remaining
"dead" chemical and remove the body from the nest.
单选题
What is meant by "death chemical" mentioned in paragraph 3?
A. A chemical that contains poison.
B. A chemical that causes death.
C. A chemical that announces death.
D. A chemical that prevents death.
【正确答案】
C
【答案解析】[解析] 根据第三段“Choe says that the living ants—not just the dead ones—have this death chemicals．”可知，Choe讲到，活着的蚂蚁——而不是死了的蚂蚁——本身带有这种宣布死亡的化学成分，所以答案为C。
单选题
Which of the following statements is NOT true of ants?
A. Ants know very soon that another ant is dead.
B. When an ant is dead, others move its body out of the nest.
C. If an ant is unconscious, it is moved out of the nest.
D. Living ants have the "I'm dead" chemical on their bodies.
【正确答案】
C
【答案解析】[解析] 根据第一段第一句话“when an ant dies, other ants move the dead insect out of the nest．”可知，当一只蚂蚁死了时，其他的蚂蚁把它移出洞穴外，而不是蚂蚁没有意识的时候就把它移走，所以答案为C。
单选题
According to Choe's hypothesis, ______.
A. an ant still smells like a living when it dies.
B. the "I am dead" chemical leaves the ant's body when it dies.
C. the "I am not dead yet" chemical is left when an ant dies.
D. the "I am not dead yet" chemical leaves the ant's body when it
dies.
【正确答案】
D
【答案解析】[解析] 根据第六段“when other ants detect the "dead" chelllical without the "not dead yet" chemical, they haul away the body.”可知，当其他蚂蚁发现死亡化学成分中没有“我还没有死”时，他们就把尸体移走，由此可知，Choe的假设是如果蚂蚁死了，身体上的“我还没有死”的化学成分就离开身体，所以答案为D。
单选题
According to paragraph 7, what is the result of the test on Choe's
hyothesis?
A. It shows that his hypothesis is wrong.
B. It proves that his hypothesis is convincing.
C. It suggests that his hypothesis needs revising.
D. Not enough evidence has been found to support his hypothesis.
【正确答案】
B
【答案解析】[解析] 根据第七段内容“And that when an ant dies, the 'not dead yet' chemicals fade away.”可知，当蚂蚁死了，“还没有死亡”的化学成分随之消失，这论证了Choe的假设，所以答案为B。
单选题
The passage "Night of the Living Ants" tells us about ______.