The human appendix is a small worm-shaped organ attached to the large intestine. Appendicitis, a potentially fatal inflammation of the appendix that often strikes young adults, was extremely rare before about 1890, but it is quite common today. In 1871, Charles Darwin compared the human appendix with the larger appendixes of many animals. Based on the rarity of appendicitis at the time, he concluded that the appendix in humans had no function-it neither helped nor harmed us. It was a vestige (a part of an organism that has become function-less), steadily withering away as people changed their diets.
With little to indicate otherwise, the vestigial status of the appendix was barely questioned for the next 100 years, and the perception of its uselessness is only enhanced by its tendency to cause a nuisance. So pointless has the medical establishment assumed it to be, that by the 1950s, removing it became one of the most common surgical procedures carried out in the developed world. An appendectomy (appendix removal)was even often tacked on as a bonus during other abdominal surgery. At one point, a man stood a one in eight chance of having his appendix removed during his lifetime, and for a woman, the odds were one in four. About 5-10 percent of people get appendicitis at some stage in their life, usually in the decades before they have children. Untreated, nearly half of these people would die.
This presents a conundrum. If appendicitis were a naturally occurring disease, frequently causing death at a young age, then the appendix would be quickly eliminated by natural selection. Those with appendixes large enough to become infected would die, most often before reproducing, and would therefore fail to pass on their appendix-forming genes. Over time, fewer and fewer people would have an appendix, and eventually it would be lost. Natural selection would have preferred those without one. Darwin’s assumption that it was a relic of our past might have carried some weight, were it not for the often fatal consequences of possessing one. There are two explanations, therefore, for the persistence of the appendix, and they are not mutually exclusive. The first is that appendicitis is a modern phenomenon brought on by some environmental change. Thus, even a pointless organ could have persisted in the past simply by keeping out of trouble. The other is that the appendix, far from being a malign vestige of our evolutionary past, actually has health benefits that outweigh its dark side, making its presence worthwhile despite the risk of appendicitis-natural selection prefers those of us who possess one. The question is, why?
The answer lies in its contents. The appendix, which averages about 8 centimeters in length and a centimeter across, forms a tube, protected from the flow of mostly digested food passing its entrance. But rather than being a withered strand of flesh, it is packed full of specialized immune cells and molecules. They are an integral part of the immune system, protecting, cultivating and communicating with a collective of microbes. Inside, these microbes form”biofilm”-a layer of individuals that support one another and exclude bacteria that might cause harm. The appendix, far from being function-less, appears to be a safe-house that the human body has provided for its microbial inhabitants.
This microbial stockpile comes in handy at times of strife. After an episode of food poisoning or a gastrointestinal infection, the gut can be repopulated with its normal inhabitants, which have been held in the appendix. It might seem like an excessive bodily insurance, but it is only in recent decades that gut infections such as dysentery, cholera and giardiasis have been all but eliminated in the Western world. Public sanitation measures, including sewerage systems and water treatment plants, have prevented such illnesses in developed countries, but globally one in five of all childhood deaths are still caused by infectious diarrhea. For those who do not succumb, possession of an appendix likely hastens their recovery. It is only in a context of relatively good health that we have come to believe that the appendix has no function. Indeed, the negative consequences of undergoing an appendectomy have been masked by the modern, sanitized lifestyle.
1
The human appendix is a small worm-shaped organ attached to the large intestine. Appendicitis, a potentially fatal inflammation of the appendix that often strikes young adults, was extremely rare before about 1890, but it is quite common today. In 1871, Charles Darwin compared the human appendix with the larger appendixes of many animals. Based on the rarity of appendicitis at the time, he concluded that the appendix in humans had no function-it neither helped nor harmed us. It was a vestige (a part of an organism that has become function-less), steadily withering away as people changed their diets.
According to paragraph 1, which of the following led Darwin to conclude that the human appendix was a vestige?
AThe appendix is attached to a larger organ.
BThe appendix did not seem to be useful or cause damage.
CNon-vestige appendixes are mostly found in larger animals.
DAppendicitis became more common than it had been.
2
With little to indicate otherwise, the vestigial status of the appendix was barely questioned for the next 100 years, and the perception of its uselessness is only enhanced by its tendency to cause a nuisance. So pointless has the medical establishment assumed it to be, that by the 1950s, removing it became one of the most common surgical procedures carried out in the developed world. An appendectomy (appendix removal)was even often tacked on as a bonus during other abdominal surgery. At one point, a man stood a one in eight chance of having his appendix removed during his lifetime, and for a woman, the odds were one in four. About 5-10 percent of people get appendicitis at some stage in their life, usually in the decades before they have children. Untreated, nearly half of these people would die.
Why does the author provide the information that “At one point, a man stood a one in eight chance of having his appendix removed during his lifetime, and for a woman, the odds were one in four”?
ATo support the claim that doctors performed more appendectomies on women than on men
BTo suggest that appendectomies have become less common since the 1950s
CTo provide evidence that people often get appendicitis before they have children
DTo help illustrate how useless doctors assumed the appendix to be
3
This presents a conundrum. If appendicitis were a naturally occurring disease, frequently causing death at a young age, then the appendix would be quickly eliminated by natural selection. Those with appendixes large enough to become infected would die, most often before reproducing, and would therefore fail to pass on their appendix-forming genes. Over time, fewer and fewer people would have an appendix, and eventually it would be lost. Natural selection would have preferred those without one. Darwin’s assumption that it was a relic of our past might have carried some weight, were it not for the often fatal consequences of possessing one. There are two explanations, therefore, for the persistence of the appendix, and they are not mutually exclusive. The first is that appendicitis is a modern phenomenon brought on by some environmental change. Thus, even a pointless organ could have persisted in the past simply by keeping out of trouble. The other is that the appendix, far from being a malign vestige of our evolutionary past, actually has health benefits that outweigh its dark side, making its presence worthwhile despite the risk of appendicitis-natural selection prefers those of us who possess one. The question is, why?
Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
AThe appendix is a vestige of our evolutionary past that used to have health benefits but no longer does.
BDespite its potential health benefits, the appendix is considered a malign vestige because of the risk of appendicitis.
CIf the appendix’s benefits outweigh the risks of appendicitis, natural selection prefers people who possess one.
DNatural selection has caused the appendix to evolve from having health risks to having health benefits.
4
This presents a conundrum. If appendicitis were a naturally occurring disease, frequently causing death at a young age, then the appendix would be quickly eliminated by natural selection. Those with appendixes large enough to become infected would die, most often before reproducing, and would therefore fail to pass on their appendix-forming genes. Over time, fewer and fewer people would have an appendix, and eventually it would be lost. Natural selection would have preferred those without one. Darwin’s assumption that it was a relic of our past might have carried some weight, were it not for the often fatal consequences of possessing one. There are two explanations, therefore, for the persistence of the appendix, and they are not mutually exclusive. The first is that appendicitis is a modern phenomenon brought on by some environmental change. Thus, even a pointless organ could have persisted in the past simply by keeping out of trouble. The other is that the appendix, far from being a malign vestige of our evolutionary past, actually has health benefits that outweigh its dark side, making its presence worthwhile despite the risk of appendicitis-natural selection prefers those of us who possess one. The question is, why?
Paragraph 3 suggests which of the following as one possible explanation for the present existence of the appendix in the human body?
AAppendix-forming genes pass on to later generations because appendicitis tends to occur among older people.
BEnvironmental changes do not affect natural selection as much as Darwin thought.
CThe organ is too large to be simply eliminated by natural selection.
DAppendicitis was not common enough in the past to cause the elimination of the organ
5
The answer lies in its contents. The appendix, which averages about 8 centimeters in length and a centimeter across, forms a tube, protected from the flow of mostly digested food passing its entrance. But rather than being a withered strand of flesh, it is packed full of specialized immune cells and molecules. They are an integral part of the immune system, protecting, cultivating and communicating with a collective of microbes. Inside, these microbes form”biofilm”-a layer of individuals that support one another and exclude bacteria that might cause harm. The appendix, far from being function-less, appears to be a safe-house that the human body has provided for its microbial inhabitants.
The word “integral” in the passage is closest in meaning to
Aessential
Bseparate
Cactive
Dunusual
6
The answer lies in its contents. The appendix, which averages about 8 centimeters in length and a centimeter across, forms a tube, protected from the flow of mostly digested food passing its entrance. But rather than being a withered strand of flesh, it is packed full of specialized immune cells and molecules. They are an integral part of the immune system, protecting, cultivating and communicating with a collective of microbes. Inside, these microbes form”biofilm“-a layer of individuals that support one another and exclude bacteria that might cause harm. The appendix, far from being function-less, appears to be a safe-house that the human body has provided for its microbial inhabitants.
According to paragraph 4, the purpose of the microbial “biofilm” inside the appendix is to
Aprevent undigested food from entering the appendix
Bsupport the appendix and prevent it from withering
Cprotect the microbes inside the appendix from dangerous bacteria
Dcreate the tube-like shape of the appendix
7
This microbial stockpile comes in handy at times of strife. After an episode of food poisoning or a gastrointestinal infection, the gut can be repopulated with its normal inhabitants, which have been held in the appendix. It might seem like an excessive bodily insurance, but it is only in recent decades that gut infections such as dysentery, cholera and giardiasis have been all but eliminated in the Western world. Public sanitation measures, including sewerage systems and water treatment plants, have prevented such illnesses in developed countries, but globally one in five of all childhood deaths are still caused by infectious diarrhea. For those who do not succumb, possession of an appendix likely hastens their recovery. It is only in a context of relatively good health that we have come to believe that the appendix has no function. Indeed, the negative consequences of undergoing an appendectomy have been masked by the modern, sanitized lifestyle.
According to paragraph 5, which of the following describes the role of the appendix after an episode of food poisoning or gastrointestinal infection?
AThe appendix releases beneficial microbes that help eliminate the remaining harmful microbes from the infection.
BThe appendix reduces the risk of diarrhea, which often follows such infections.
CThe appendix helps prevent such illnesses from occurring again.
DThe appendix provides a source of microbes that the gut lost during the infection.
8
This microbial stockpile comes in handy at times of strife. After an episode of food poisoning or a gastrointestinal infection, the gut can be repopulated with its normal inhabitants, which have been held in the appendix. It might seem like an excessive bodily insurance, but it is only in recent decades that gut infections such as dysentery, cholera and giardiasis have been all but eliminated in the Western world. Public sanitation measures, including sewerage systems and water treatment plants, have prevented such illnesses in developed countries, but globally one in five of all childhood deaths are still caused by infectious diarrhea. For those who do not succumb, possession of an appendix likely hastens their recovery. It is only in a context of relatively good health that we have come to believe that the appendix has no function. Indeed, the negative consequences of undergoing an appendectomy have been masked by the modern, sanitized lifestyle.
Which of the following can be inferred from paragraph 5 about the appendix?
AIt is more useful for people outside the Western world than for people in the Western world.
BIt is more beneficial during adulthood than during childhood.
CIt helps to prevent infections such as dysentery, cholera, and giardiasis.
DIts infection can be prevented by measures like sewerage systems and water treatment plants.
9
The human appendix is a small worm-shaped organ attached to the large intestine.■ Appendicitis, a potentially fatal inflammation of the appendix that often strikes young adults, was extremely rare before about 1890, but it is quite common today. ■ In 1871, Charles Darwin compared the human appendix with the larger appendixes of many animals. ■Based on the rarity of appendicitis at the time, he concluded that the appendix in humans had no function-it neither helped nor harmed us.■ It was a vestige (a part of an organism that has become function-less), steadily withering away as people changed their diets.
Look at the four squaresthat indicate where the following sentence could be added to the passage
That the appendix can cause this problem was known for some time, but the organ’s function remained a mystery.
Where would the sentence best fit？Click on a square sentence to the passage.
10
The appendix is a small organ whose function was unknown for a long time.
ALow rates of appendicitis in animals led Darwin and others to believe that appendicitis was related to changes in the human diet.
BIf appendicitis is a natural disease, rather than one caused by recent environmental changes, the appendix’s continued existence as a vestige would be surprising.
CScientists began to understand the purpose of the appendix when they discovered that infectious diseases and food poisoning were more common in people who had their appendixes removed.
DRemoving the appendix was a very common procedure during the 20th century, as keeping the organ did not seem to have obvious benefits that outweighed the risk of appendicitis.
EThe human appendix has become smaller and smaller over time, particularly in Western countries, as many gastrointestinal infections have been almost completely eliminated.
FThe immune cells and microbes in the appendix probably help people recover from infections, although this benefit is not obvious in places with public sanitation.
