Passage TwoQuestions 26 to 30 are based on the following passage.
Ever since Darwin’s theory of evolution, biologists have assumed that environments teeming with complex forms of life served as the nurseries of evolution. But two recent papers in Science magazine have turned that notion on its head. Last month some biologists reported that in the ocean it is the relatively barren areas that serve as “evolutionary crucibles(熔爐),” not regions with great diversity of species. Other researchers announced this summer that the Arctic, not the rain forest, spawned many plants and animals that later migrated to North America. Says John Sepkoski of the University of Chicago, “Harsh environments may be producing the major changes in the history of life.”
These “changes” do not result merely in a longer tail or a bigger claw for an existing species but, rather, in dramatic leaps up the evolutionary ladder—a rare innovation that comes along once in a million years. In the Arctic, reports Leo Hickey of Yale University, the innovations ran to forms never before seen on earth. By dating fossils from many geologic layers, he concluded that large grazing animals first appeared in the Arctic and migrated to temperate places a couple of million years or so later. Among plants, species of redwood and birch originated in polar regions some 18 millions years before they showed up in the south. Examining fossils as old as 570 million years, Chicago’s Sepkoski found that shell-less, soft-bodied creatures were suddenly replaced by trilobites（三葉蟲）, then by the more advanced clam-like animals. These changes, he notes, “first become common near shore.” That surprised him—an environment with as few species as exist in the near shore, and with such a poor record of producing new species, seems an unlikely place for biological innovation. But when Jablonski dated fossils of 100 million years ago, he found that during this era, too, the near shore spawned biological breakthroughs—more sophisticated sea creatures that move and find food in ocean sediments instead of passively filtering whatever floats by.
The findings are too new to apply to human evolution, but at first glance they seem to fit the facts. Anthropologists believe that our ancestors became fully human only after they left their secure life in the trees for the harsh world of savanna(plain without trees). There, the demanding conditions triggered that most human of traits, the large brain, and the most profound evolutionary step of all was taken.
26. Two recent papers in Science magazine claim to have found evidence which contradicts the traditional notion that
.
A) relatively harsh environments are the nurseries of evolution
B) evolution occurred in regions with biological diversity
C) new forms of life come into being in near-shore areas
D) species of birch and redwood originated in the south
27. According to Leo Hickey of Yale University, which of the following may have spawned more advanced species of land animals?
A) The barren ocean floor.B) The Arctic.
C) The rain forest.D) Temperate Zones.
28. The word “innovations” in the second paragraph means
.
A) new theoryB) new phenomenonC) changesD) new inventions
29. How would anthropologists take the new findings?
A) They would look at them dubiously.
B) They would eagerly apply them to the study of human evolution.
C) They would challenge them, though at first glance they tend to look at them favorably.
D) They would most probably think the new findings fit well into their theory.
30. Which of the following may be an appropriate title of the passage?
A) Darwin’s Theory Modified.B) How Animals Evolve.
C) Evolution in Hard Places.D) Where Did Large Sea Animals Originate.
Passage Three
Questions 31 to 35 are based on the following passage.
That question “why women live longer than men” can be answered at two levels. An evolutionary biologist would tell you that it is because women get evolutionary bonus points from living long enough to help bring up the grandchildren. Men, by contrast, wear themselves out competing for the right to procreate in the first place. That is probably true, but not much help to the medical profession. However, a group of researchers at John Moores University has just come up with a medically useful answer. It is that while 70-year-old men have the hearts of 70-year-olds, those of their female peers resemble the hearts of 20-year-olds.
David Goldspink and his colleagues looked at 250 volunteers aged between 18 and 80 over two years. All the volunteers were healthy but physically inactive. The team’s principal finding was that the power of the male heart falls by 20-25% between the ages of 18 and 70, while that of the female heart remains undiminished.
They found that between the ages of 20 and 70, men lose 1/3 of the contractile muscle cells in the walls of their hearts. Over the same period, women lose hardly any. There is a strong link between the number of these cells and the function of the heart. What remains a mystery is why men lose these cells and women do not.
A previous theory of why women outlive men suggested that the female sex hormone, oestrogen, could have a protective effect on the heart. But Dr. Goldspink dismisses this idea, saying that there is no discernible dropoff in female heart function after menopause （更年期）, when oestrogen （雌激素） levels decrease dramatically. However, oestrogen does have a beneficial effect on blood vessels. The study found that blood flow to the muscles and skin of the limbs decreases with age in both sexes. The changes in the structure of the blood vessels occur earlier in men, but women catch up soon after menopause.
It’s not all bad news for men, though. In a related study, the team found that the hearts of veteran male athletes were as powerful as those of inactive 20yearold male undergraduates. But can men really recover lost heart function after a lifetime of inactivity and poor diet? Is it ever too late to start exercising? “I think the answer is no,” says Dr. Goldspink. “The health benefits to be gained from sensible exercise are to be recommended, regardless of age.” So if you are male and getting on, get on with it
31. A medical explanation as to the question why women live longer than men is that
.A) women have to live long enough to look after grandchildren
B) women’s hearts hardly grow old
C) women have more endurance than men
D) women are superior at evolutionary scale
32. The power of the female heart remains undiminished between the ages of 18 and 70 probably because
.
A) women almost lose no contractile muscle cells in the walls of their hearts
B) women’s oestrogen has a protective effect on their heart
C) the size of their heart chambers is different from men’s
D) the thickness of the female heart’s muscular wall is different from men’s
33. Dr. Goldspink disagrees with the proposal that oestrogen could protect heart because
.
A) female sex hormone can increase blood flow
B) female sex hormone can be beneficial to blood vessels
C) female heart function hardly drops when oestrogen levels fall greatly
D) female heart function improves though not obviously
34. What Dr. Goldspink says to men is that
.
A) men can’t recover lost heart function in any way
B) men can recover lost heart function at any age
C) proper exercise does good to the heart at any age
D) it’s too late to start exercise when men are getting old
35. The best title of the passage is
.A) Exercise and the Health of Heart
B) The Difference between Men and Women
C) Heart and Health
D) Why Do Women Live Longer than Men
Passage Four
Questions 36 to 40 are based on the following passage.
In the past, concern about a man-made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctic, which may be affected by only a few degrees of warming: in other words, by a warming on the scale that will possibly take place in the next fifty years from the burning of fuels.
Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warm the earth.
However, most of the fuel is burnt in the northern hemisphere, where temperatures seem to be falling. Scientists conclude, therefore, that up to now natural influences on the weather have exceeded those caused by man. The question is: which natural cause has most effect on the weather?
One possibility is the variable behavior of the sun. Astronomers at one research station have studied the hot spots and “cold” spots (that is, the relatively less hot spots) on the sun. As the sun rotated, every 27.5 days, it presents hotter or “colder” faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earth’s atmospheric pressure, and consequently on wind circulation. The sun is also variable over a long term: its heat output goes up and down in cycles, the latest trend being downward.
Scientists are now finding mutual relations between models of solar-weather interactions and the actual climate over many thousands of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia of the earth’s climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful counter-balance to the sun’s diminishing heat.
36. Experts used to believe that the chief reason for global warming is .
A) that most fuel is consumed in the northern hemisphere
B) human activities
C) natural influences and carbon dioxide
D) the solar energy
37. The article is written to illustrate
.
A) the greenhouse effect
B) the solar effects on the earth
C) the models of solar-weather interactions
D) the factors responsible for the global climate
38. In spite of the greater consumption of fuel in the northern hemisphere, temperatures seem to be falling. This is
.A) possibly because of the melting of the ice caps in the poles
B) mainly because the levels of carbon dioxide are rising
C) partly due to the variations of the output of solar energy
D) because the sun presents its “colder” face to the earth
39. On the basis of the models, scientists are of the opinion that
.
A) the climate of the world should be becoming cooler
B) it’ll take thousands of years for the inertia of the earth’s climate to take effect
C) the man-made warming effect helps to increase the solar effects
D) the new Ice Age will be delayed by the greenhouse effect
40. If the assumption about the delay of a new Ice Age is correct
.
A) the increased levels of carbon dioxide will warm up the earth even more quickly
B) the greenhouse effect will work to the advantage of the earth
C) the best way to overcome the cooling effect will be to burn more fuels
D) ice will soon cover the northern hemisphere
