I. Kiến thức liên quan
II. Tổng hợp topic Environment (Biology, Agriculture,...) IELTS READING (PDF) (Phần 3)
27. Bài 27
Collecting Ant Specimens
Collecting ants can be as simple as picking up stray ones and placing them in a glass jar, or as complicated as completing an exhaustive survey of all species present in an area and estimating their relative abundances. The exact method used will depend on the final purpose of the collections. For taxonomy. or classification, long series, from a single nest, which contain all castes (workers, including majors and minors, and, if present, queens and males) are desirable, to allow the determination of variation within species. For ecological studies, the most important factor is collecting identifiable samples of as many of the different species present as possible. Unfortunately, these methods are not always compatible. The taxonomist sometimes overlooks whole species in favour of those groups currently under study, while the ecologist often collects only a limited number of specimens of each species, thus reducing their value for taxonomic investigations.
To collect as wide a range of species as possible, several methods must be used. These include hand collecting, using baits to attract the ants, ground litter sampling, and the use of pitfall traps. Hand collecting consists of searching for ants everywhere they are likely to occur. This includes on the ground, under rocks, logs or other objects on the ground, in rotten wood on the ground or on trees, in vegetation, on tree trunks and under bark. When possible, collections should be made from nests or foraging columns and at least 20 to 25 individuals collected. This will ensure that all individuals are of the same species, and so increase their value for detailed studies. Since some species are largely nocturnal. collecting should not be confined to daytime. Specimens are collected using an aspirator (often called a pooter), forceps, a fine, moistened paint brush, or fingers. if the ants are known not to sting. Individual insects are placed in plastic or glass tubes (1.5-3.0 ml capacity for small ants, 5-8 ml for larger ants) containing 75% to 95% ethanol. Plastic tubes with secure tops are better than glass because they are lighter, and do not break as easily if mishandled.
Baits can be used to attract and concentrate foragers. This often increases the number of individuals collected and attracts species that are otherwise elusive. Sugars and meats or oils will attract different species and a range should be utilised. These baits can be placed either on the ground or on the trunks of trees or large shrubs. When placed on the ground, baits should be situated on small paper cards or other flat, light-coloured surfaces, or in test-tubes or vials. This makes it easier to spot ants and to capture them before they can escape into the surrounding leaf litter.
Many ants are small and forage primarily in the layer of leaves and other debris on the ground. Collecting these species by hand can be difficult. One of the most successful ways to collect them is to gather the leaf litter in which they are foraging and extract the ants from it. This is most commonly done by placing leaf litter on a screen over a large funnel, often under some heat. As the leaf litter dries from above, ants (and other animals) move downward and eventually fall out the bottom and are collected in alcohol placed below the funnel. This method works especially well in rainforests and marshy areas. A method of improving the catch when using a funnel is to sift the leaf litter through a coarse screen before placing it above the funnel. This will concentrate the litter and remove larger leaves and twigs. It will also allow more litter to be sampled when using a limited number of funnels.
The pitfall trap is another commonly used tool for collecting ants. A pitfall trap can be any small container placed on the ground with the top level with the surrounding surface and filled with a preservative. Ants are collected when they fall into the trap while foraging. The diameter of the traps can vary from about 18 mm to 10 cm and the number used can vary from a few to several hundred. The size of the traps used is influenced largely by personal preference (although larger sizes are generally better), while the number will be determined by the study being undertaken. The preservative used is usually ethylene glycol or propylene glycol, as alcohol will evaporate quickly and the traps will dry out. One advantage of pitfall traps is that they can be used to collect over a period of time with minimal maintenance and intervention. One disadvantage is that some species are not collected as they either avoid the traps or do not commonly encounter them while foraging.
Do the following statements agree with the information given in Reading Passage 3? In boxes 27-30 on your answer sheet, write:
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this
27. Taxonomic research involves comparing members of one group of ants.
28. New species of ant are frequently identified by taxonomists.
29. Range is the key criterion for ecological collections.
30. A single collection of ants can generally be used for both taxonomic and ecological purposes.
Classify the following statements as referring to
A. hand collecting
B. using bait
C. sampling ground litter
D. using a pitfall trap
Write the correct letter, A, B, C or D, in boxes 31-36 on your answer sheet.
31. It is preferable to take specimens from groups of ants.
32. It is particularly effective for wet habitats.
33. It is a good method for species which are hard to find.
34. Little time and effort is required.
35. Separate containers are used for individual specimens.
36. Non-alcoholic preservative should be used.
Label the diagram below. Choose NO MORE THAN TWO WORDS from the passage for each answer. Write your answers in boxes 37-40 on your answer sheet.
28. Bài 28
The History Of The Tortoise
If you go back far enough, everything lived in the sea. At various points in evolutionary history, enterprising individuals within many different animal groups moved out onto the land, sometimes even to the most parched deserts, taking their own private seawater with them in blood and cellular fluids. In addition to the reptiles, birds, mammals and insects which we see all around us, other groups that have succeeded out of water include scorpions, snails, crustaceans such as woodlice and land crabs, millipedes and centipedes, spiders and various worms. And we mustn’t forget the plants, without whose prior invasion of the land none of the other migrations could have happened.
Moving from water to land involved a major redesign of every aspect of life, including breathing and reproduction. Nevertheless, a good number of thoroughgoing land animals later turned around, abandoned their hard-earned terrestrial re-tooling, and returned to the water again. Seals have only gone part way back. They show us what the intermediates might have been like, on the way to extreme cases such as whales and dugongs. Whales (including the small whales we call dolphins) and dugongs, with their close cousins the manatees, ceased to be land creatures altogether and reverted to the full marine habits of their remote ancestors. They don’t even come ashore to breed. They do, however, still breathe air, having never developed anything equivalent to the gills of their earlier marine incarnation. Turtles went back to the sea a very long time ago and, like all vertebrate returnees to the water, they breathe air. However, they are, in one respect, less fully given back to the water than whales or dugongs, for turtles still lay their eggs on beaches.
There is evidence that all modem turtles are descended from a terrestrial ancestor which lived before most of the dinosaurs. There are two key fossils called Proganochelys quenstedti and Palaeochersis talampayensis dating from early dinosaur times, which appear to be close to the ancestry of all modem turtles and tortoises. You might wonder how we can tell whether fossil animals lived on land or in water, especially if only fragments are found. Sometimes it’s obvious. Ichthyosaurs were reptilian contemporaries of the dinosaurs, with fins and streamlined bodies. The fossils look like dolphins and they surely lived like dolphins, in the water. With turtles it is a little less obvious. One way to tell is by measuring the bones of their forelimbs.
Walter Joyce and Jacques Gauthier, at Yale University, obtained three measurements in these particular bones of 71 species of living turtles and tortoises. They used a kind of triangular graph paper to plot the three measurements against one another. All the land tortoise species formed a tight cluster of points in the upper part of the triangle; all the water turtles cluster in the lower part of the triangular graph. There was no overlap, except when they added some species that spend time both in water and on land. Sure enough, these amphibious species show up on the triangular graph approximately half way between the ‘wet cluster’ of sea turtles and the ‘dry cluster’ of land tortoises. The next step was to determine where the fossils fell. The bones of P quenstedti and JR talampayensis leave us in no doubt. Their points on the graph are right in the thick of the dry cluster. Both these fossils were dry-land tortoises. They come from the era before our turtles returned to the water.
You might think, therefore, that modem land tortoises have probably stayed on land ever since those early terrestrial times, as most mammals did after a few of them went back to the sea. But apparently not. If you draw out the family tree of all modem turtles and tortoises, nearly all the branches are aquatic. Today’s land tortoises constitute a single branch, deeply nested among branches consisting of aquatic turtles. This suggests that modem land tortoises have not stayed on land continuously since the time of P. quenstedti and P. talampayensis. Rather, their ancestors were among those who went back to the water, and they then re-emerged back onto the land in (relatively) more recent times.
Tortoises therefore represent a remarkable double return. In common with all mammals, reptiles and birds, their remote ancestors were marine fish and before that various more or less worm-like creatures stretching back, still in the sea, to the primeval bacteria. Later ancestors lived on land and stayed there for a very large number of generations. Later ancestors still evolved back into the water and became sea turtles. And finally they returned yet again to the land as tortoises, some of which now live in the driest of deserts.
Answer the questions below. Choose NO MORE THAN TWO WORDS from the passage for each answer. Write your answers in boxes 27-30 on your answer sheet.
27. What had to transfer from sea to land before any animals could migrate?
28. Which TWO processes are mentioned as those in which animals had to make big changes as they moved onto land?
29. Which physical feature, possessed by their ancestors, do whales lack?
30. Which animals might ichthyosaurs have resembled?
Do the following statements agree with the information given in Reading Passage 3? In boxes 31-33 on your answer sheet, write:
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this more than once.
31. Turtles were among the first group of animals to migrate back to the sea.
32. It is always difficult to determine where an animal lived when its fossilized remains are incomplete.
33. The habitat of ichthyosaurs can be determined by the appearance of their fossilized remains.
Complete the flow-chart below. Choose NO MORE THAN TWO WORDS AND/OR A NUMBER from the passage for each answer. Write your answers in boxes 34-39 on your answer sheet.
Choose the correct letter A, B, C or D. Write the correct letter in box 40 on your answer sheet.
According to the writer, the most significant thing about tortoises is that
A. they are able to adapt to life in extremely dry environments.
B. their original life form was a kind of primeval bacteria.
C. they have so much in common with sea turtles.
D. they have made the transition from sea to land more than once.
29. Bài 29
A millennium ago, stepwells were fundamental to life in the driest parts of India. Although many have been neglected, recent restoration has returned them to their former glory. Richard Cox travelled to north-western India to document these spectacular monuments from a bygone era.
During the sixth and seventh centuries, the inhabitants of the modern-day states of Gujarat and Rajasthan in North-western India developed a method of gaining access to clean, fresh groundwater during the dry season for drinking, bathing, watering animals and irrigation. However, the significance of this invention – the stepwell – goes beyond its utilitarian application.
Unique to the region, stepwells are often architecturally complex and vary widely in size and shape. During their heyday, they were places of gathering, of leisure, of relaxation and of worship for villagers of all but the lowest castes. Most stepwells are found dotted around the desert areas of Gujarat (where they are called vav) and Rajasthan (where they are known as baori), while a few also survive in Delhi. Some were located in or near villages as public spaces for the community; others were positioned beside roads as resting places for travellers.
As their name suggests, stepwells comprise a series of stone steps descending from ground level to the water source (normally an underground aquifer) as it recedes following the rains. When the water level was high, the user needed only to descend a few steps to reach it; when it was low, several levels would have to be negotiated.
Some wells are vast, open craters with hundreds of steps paving each sloping side, often in tiers. Others are more elaborate, with long stepped passages leading to the water via several storeys built from stone and supported by pillars, they also included pavilions that sheltered visitors from the relentless heat. But perhaps the most impressive features are the intricate decorative sculptures that embellish many stepwells, showing activities from fighting and dancing to everyday acts such as women combing their hair and churning butter.
Down the centuries, thousands of wells were constructed throughout northwestern India, but the majority have now fallen into disuse; many are derelict and dry, as groundwater has been diverted for industrial use and the wells no longer reach the water table. Their condition hasn’t been helped by recent dry spells: southern Rajasthan suffered an eight-year drought between 1996 and 2004.
However, some important sites in Gujarat have recently undergone major restoration, and the state government announced in June last year that it plans to restore the stepwells throughout the state.
In Patan, the state’s ancient capital, the stepwell of Rani Ki Vav (Queen’s Stepwell) is perhaps the finest current example. It was built by Queen Udayamati during the late 11th century, but became silted up following a flood during the 13th century. But the Archaeological Survey of India began restoring it in the 1960s, and today it’s in pristine condition. At 65 metres long, 20 metres wide and 27 metres deep, Rani Ki Vav features 500 distinct sculptures carved into niches throughout the monument, depicting gods such as Vishnu and Parvati in various incarnations. Incredibly, in January 2001, this ancient structure survived a devastating earthquake that measured 7.6 on the Richter scale.
Another example is the Surya Kund in Modhera, northern Gujarat, next to the Sun Temple, built by King Bhima I in 1026 to honour the sun god Surya. It’s actually a tank (kund means reservoir or pond) rather than a well, but displays the hallmarks of stepwell architecture, including four sides of steps that descend to the bottom in a stunning geometrical formation. The terraces house 108 small, intricately carved shrines between the sets of steps.
Rajasthan also has a wealth of wells. The ancient city of Bundi, 200 kilometres south of Jaipur, is renowned for its architecture, including its stepwells. One of the larger examples is Raniji Ki Baori, which was built by the queen of the region, Nathavatji, in 1699. At 46 metres deep, 20 metres wide and 40 metres long, the intricately carved monument is one of 21 baoris commissioned in the Bundi area by Nathavatji.
In the old ruined town of Abhaneri, about 95 kilometres east of Jaipur, is Chand Baori, one of India’s oldest and deepest wells; aesthetically, it’s perhaps one of the most dramatic. Built in around 850 AD next to the temple of Harshat Mata, the baori comprises hundreds of zigzagging steps that run along three of its sides, steeply descending 11 storeys, resulting in a striking geometric pattern when seen from afar. On the fourth side, covered verandas supported by ornate pillars overlook the steps.
Still in public use is Neemrana Ki Baori, located just off the Jaipur–Dehli highway. Constructed in around 1700, it’s nine storeys deep, with the last two levels underwater. At ground level, there are 86 colonnaded openings from where the visitor descends 170 steps to the deepest water source.
Today, following years of neglect, many of these monuments to medieval engineering have been saved by the Archaeological Survey of India, which has recognised the importance of preserving them as part of the country’s rich history. Tourists flock to wells in far-flung corners of northwestern India to gaze in wonder at these architectural marvels from 1,000 years ago, which serve as a reminder of both the ingenuity and artistry of ancient civilisations and of the value of water to human existence.
Do the following statements agree with the information given in Reading Passage 1? In boxes 1–5 on your answer sheet, write:
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this
1. Examples of ancient stepwells can be found all over the world.
2. Stepwells had a range of functions, in addition to those related to water collection.
3. The few existing stepwells in Delhi are more attractive than those found elsewhere.
4. It took workers many years to build the stone steps characteristic of stepwells.
5. The number of steps above the water level in a stepwell altered during the course of a year.
Answer the questions below. Choose ONE WORD ONLY from the passage for each answer. Write your answers in boxes 6–8 on your answer sheet.
6. Which part of some stepwells provided shade for people?
7. What type of serious climatic event, which took place in southern Rajasthan, is mentioned in the article? 7
8. Who are frequent visitors to stepwells nowadays?
Complete the table below. Choose ONE WORD AND /OR A NUMBER from the passage for each answer. Write your answers in boxes 9-13 on your answer sheet.
30. Bài 30
Canadian writer Jay Ingram investigates the mystery of why leaves turn red in the fall
A. One of the most captivating natural events of the year in many areas throughout North America is the turning of the leaves in the fall. The colours are magnificent, but the question of exactly why some trees turn yellow or orange, and others red or purple, is something which has long puzzled scientists.
B. Summer leaves are green because they are full of chlorophyll, the molecule that captures sunlight converts that energy into new building materials for the tree. As fall approaches in the northern hemisphere, the amount of solar energy available declines considerably. For many trees – evergreen conifers being an exception – the best strategy is to abandon photosynthesis* until the spring. So rather than maintaining the now redundant leaves throughout the winter, the tree saves its precious resources and discards them. But before letting its leaves go, the tree dismantles their chlorophyll molecules and ships their valuable nitrogen back into the twigs. As chlorophyll is depleted, other colours that have been dominated by it throughout the summer begin to be revealed. This unmasking explains the autumn colours of yellow and orange, but not the brilliant reds and purples of trees such as the maple or sumac.
C. The source of the red is widely known: it is created by anthocyanins, water-soluble plant pigments reflecting the red to blue range of the visible spectrum. They belong to a class of sugar-based chemical compounds also known as flavonoids. What’s puzzling is that anthocyanins are actually newly minted, made in the leaves at the same time as the tree is preparing to drop them. But it is hard to make sense of the manufacture of anthocyanins – why should a tree bother making new chemicals in its leaves when it’s already scrambling to withdraw and preserve the ones already there?
D. Some theories about anthocyanins have argued that they might act as a chemical defence against attacks by insects or fungi, or that they might attract fruit-eating birds or increase a leaf's tolerance to freezing. However, there are problems with each of these theories, including the fact that leaves are red for such a relatively short period that the expense of energy needed to manufacture the anthocyanins would outweigh any anti-fungal or anti-herbivore activity achieved.* photosynthesis: the production of new material from sunlight, water and carbon dioxide.
E. It has also been proposed that trees may produce vivid red colours to convince herbivorous insects that they are healthy and robust and would be easily able to mount chemical defences against infestation. If insects paid attention to such advertisements, they might be prompted to lay their eggs on a duller, and presumably less resistant host. The flaw in this theory lies in the lack of proof to support it. No one has as yet ascertained whether more robust trees sport the brightest leaves, or whether insects make choices according to colour intensity.
F. Perhaps the most plausible suggestion as to why leaves would go to the trouble of making anthocyanins when they’re busy packing up for the winter is the theory known as the ‘light screen’ hypothesis. It sounds paradoxical, because the idea behind this hypothesis is that the red pigment is made in autumn leaves to protect chlorophyll, the light-absorbing chemical, from too much light. Why does chlorophyll need protection when it is the natural world’s supreme light absorber? Why protect chlorophyll at a time when the tree is breaking it down to salvage as much of it as possible?
G. Chlorophyll, although exquisitely evolved to capture the energy of sunlight, can sometimes be overwhelmed by it, especially in situations of drought, low temperatures, or nutrient deficiency. Moreover, the problem of oversensitivity to light is even more acute in the fall, when the leaf is busy preparing for winter by dismantling its internal machinery. The energy absorbed by the chlorophyll molecules of the unstable autumn leaf is not immediately channelled into useful products and processes, as it would be in an intact summer leaf. The weakened fall leaf then becomes vulnerable to the highly destructive effects of the oxygen created by the excited chlorophyll molecules.
H. Even if you had never suspected that this is what was going on when leaves turn red, there are clues out there. One is straightforward: on many trees, the leaves that are the reddest are those on the side of the tree which gets most sun. Not only that, but the red is brighter on the upper side of the leaf. It has also been recognised for decades that the best conditions for intense red colours are dry, sunny days and cool nights, conditions that nicely match those that make leaves susceptible to excess light. And finally, trees such as maples usually get much redder the more north you travel in the northern hemisphere. It’s colder there, they’re more stressed, their chlorophyll is more sensitive and it needs more sunblock.
I. What is still not fully understood, however, is why some trees resort to producing red pigments while others don’t bother, and simply reveal their orange or yellow hues. Do these trees have other means at their disposal to prevent overexposure to light in autumn? Their story, though not as spectacular to the eye, will surely turn out to be as subtle and as complex.
*photosynthesis: the production of new material from sunlight, water and carbon dioxide
Reading Passage 2 has nine paragraphs, A-l.
Which paragraph contains the following information?
Write the correct letter, A-l, in boxes 14-18 on your answer sheet.
NB You may use any letter more than once.
14. a description of the substance responsible for the red colouration of leaves
15. the reason why trees drop their leaves in autumn
16. some evidence to confirm a theory about the purpose of the red leaves
17. an explanation of the function of chlorophyll
18. a suggestion that the red colouration in leaves could serve as a warning signal.
Complete the notes below. Choose ONE WORD ONLY from the passage for each answer. Write your answers in boxes 19-22 on your answer sheet.
Why believe the ‘light screen’ hypothesis?
- The most vividly coloured red leaves are found on the side of the tree facing the 19...................... .
- The 20...................... surfaces of leaves contain the most red pigment.
- Red leaves are most abundant when daytime weather conditions are 21...................... and sunny.
- The intensity of the red colour of leaves increases as you go further 22...................... .
Do the following statements agree with the information given in Reading Passage 2? In boxes 23-25 on your answer sheet, write:
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this
23. It is likely that the red pigments help to protect the leaf from freezing temperatures.
24. The ‘light screen’ hypothesis would initially seem to contradict what is known about chlorophyll.
25. Leaves which turn colours other than red are more likely to be damaged by sunlight.
Choose the correct letter A, B, C or D. Write the correct letter in box 26 on your answer sheet.
For which of the following questions does the writer offer an explanation?
A. why conifers remain green in winter
B. how leaves turn orange and yellow in autumn
C. how herbivorous insects choose which trees to lay their eggs in
D. why anthocyanins are restricted to certain trees
31. Bài 31
Beyond the blue horizon
Ancient voyagers who settled the far-flung islands of the Pacific Ocean
An important archaeological discovery on the island of Efate in the Pacific archipelago of Vanuatu has revealed traces of an ancient seafaring people, the distant ancestors of todays' Polynesians. The site came to light only by chance. An agricultural worker, digging in the grounds of a derelict plantation, scraped open a grave – the first of dozens in a burial ground some 3,000 years old. It is the oldest cemetery ever found in the Pacific islands, and it harbors the remains of an ancient people archaeologists call the Lapita.
They were daring blue-water adventurers who used basic canoes to move across the ocean. But they were not just explorers. They were also pioneers who carried with them everything they would need to build new lives – their livestock, taro seedlings and stone tools. Within the span of several centuries, the Lapita stretched the boundaries of their world from the jungle-clad volcanoes of Papua New Guinea to the loneliest coral outliers of Tonga.
The Lapita left precious few clues about themselves, but Efate expands the volume of data available to researchers dramatically. The remains of 62 individuals have been uncovered so far, and archaeologists were also thrilled to find six complete Lapita pots. Other items included a Lapita burial urn with modeled birds arranged on the rim as though peering down at the human remains sealed inside. ‘It’s an important discovery,’ says Matthew Spriggs, professor of archaeology at the Australian National University and head of the international team digging up the site, ‘for it conclusively identifies the remains as Lapita.’
DNA teased from these human remains may help answer one of the most puzzling questions in Pacific anthropology: did all Pacific islanders spring from one source or many? Was there only one outward migration from a single point in Asia, or several from different points? ‘This represents the best opportunity we’ve had yet,’ says Spriggs, ‘to find out who the Lapita actually were, where they came from, and who their closest descendants are today.’
There is one stubborn question for which archaeology has yet to provide any answers: how did the Lapita accomplish the ancient equivalent of a moon landing, many times over? No-one has found one of their canoes or any rigging, which could reveal how the canoes were sailed. Nor do the oral histories and traditions of later Polynesians offer any insights, for they turn into myths long before they reach as far back in time as the Lapita.
‘All we can say for certain is that the Lapita had canoes that were capable of ocean voyages, and they had the ability to sail them,’ says Geoff Irwin, a professor of archaeology at the University of Auckland. Those sailing skills, he says, were developed and passed down over thousands of years by earlier mariners who worked their way through the archipelagoes of the western Pacific, making short crossings to nearby islands. The real adventure didn’t begin, however, until their Lapita descendants sailed out of sight of land, with empty horizons on every side. This must have been as difficult for them as landing on the moon is for us today. Certainly, it distinguished them from their ancestors, but what gave them the courage to launch out on such risky voyages?
The Lap it as thrust into the Pacific was eastward, against the prevailing trade winds, Irwin notes. Those nagging headwinds, he argues, may have been the key to their success. ‘They could sail out for days into the unknown and assess the area, secure in the knowledge that if they didn’t find anything, they could turn about and catch a swift ride back on the trade winds. This is what would have made the whole thing work.’ Once out there, skilled seafarers would have detected abundant leads to follow to land: seabirds, coconuts and twigs carried out to sea by the tides, and the afternoon pile-up of clouds on the horizon which often indicates an island in the distance.
For returning explorers, successful or not, the geography of their own archipelagoes would have provided a safety net. Without this to go by, overshooting their home ports, getting lost and sailing off into eternity would have been all too easy. Vanuatu, for example, stretches more than 500 miles in a northwest-southeast trend, its scores of inrervisible islands forming a backstop for mariners riding the trade winds home.
All this presupposes one essential detail, says Atholl Anderson, professor of prehistory at the Australian National University: the Lapita had mastered the advanced art of sailing against the wind. ‘And there’s no proof they could do any such thing,’ Anderson says. ‘There has been this assumption they did, and people have built canoes to re-create those early voyages based on that assumption. But nobody has any idea what their canoes looked like or how they were rigged.’
Rather than give all the credit to human skill, Anderson invokes the winds of chance. El Nino, the same climate disruption that affects the Pacific today, may have helped scatter the Lapita, Anderson suggests. He points out that climate data obtained from slow-growing corals around the Pacific indicate a series of unusually frequent El Ninos around the time of the Lapita expansion. By reversing the regular east-to-west flow of the trade winds for weeks at a time, these super El Ninos might have taken the Lapita on long unplanned voyages.
However they did it, the Lapita spread themselves a third of the way across the Pacific, then called it quits for reasons known only to them. Ahead lay the vast emptiness of the central Pacific and perhaps they were too thinly stretched to venture farther. They probably never numbered more than a few thousand in total, and in their rapid migration eastward they encountered hundreds of islands – more than 300 in Fiji alone.
Questions 27 - 31
Complete the summary using the list of words and phrases, A-J, below. Write the correct letter, A-J, in boxes 27-31 on your sheet.
The Efate burial site
A 3,000-year-old burial ground of a seafaring people called the Lapita has been found on an abandoned 27.................... on the Pacific island of Efate. The cemetery, which is a significant 28...................., was uncovered accidentally by an agricultural worker.
The Lapita explored and colonised many Pacific islands over several centuries. They took many things with them on their voyages including 29.................... and tools.
The burial ground increases the amount of information about the Lapita available to scientists. A team of researchers, led by Matthew Spriggs from the Australian National University, are helping with the excavation of the site. Spriggs believes the 30.................... which was found at the site is very important since it confirms that the 31.................... found inside are Lapita.
F. archaeological discovery
G. burial urn
Choose the correct letter A, B, C or D. Write the correct letter in boxes 32-35 on your answer sheet.
32. According to the writer, there are difficulties explaining how the Lapita accomplished their journeys because
A) the canoes that have been discovered offer relatively few clues.
B) archaeologists have shown limited interest in this area of research.
C) little information relating to this period can be relied upon for accuracy.
D) technological advances have altered the way such achievements are viewed.
33. According to the sixth paragraph, what was extraordinary about the Lapita?
A) They sailed beyond the point where land was visible.
B) Their cultural heritage discouraged the expression of fear.
C) They were able to build canoes that withstood ocean voyages.
D) Their navigational skills were passed on from one generation to the next.
34. What does ‘This’ refer to in the seventh paragraph?
A) the Lapita’s seafaring talent
B) the Lapita s ability to detect signs of land
C) the Lapita’s extensive knowledge of the region
D) the Lapita’s belief they would be able to return home
35. According to the eighth paragraph, how was the geography of the region significant?
A) It played an important role in Lapita culture.
B) It meant there were relatively few storms at sea.
C) It provided a navigational aid for the Lapita.
D) It made a large number of islands habitable.
Do the following statements agree with the views of the writer in Reading Passage 3? In boxes 36-40 on your answer sheet, write:
YES if the statement agrees with the views of the writer
NO if the statement contradicts the views of the writer
NOT GIVEN if it is impossible to say what the writer thinks about this
36. It is now clear that the Lapita could sail into a prevailing wind.
37. Extreme climate conditions may have played a role in Lapita migration.
38. The Lapita learnt to predict the duration of El Ninos.
39. It remains unclear why the Lapita halted their expansion across the Pacific.
40. It is likely that the majority of Lapita settled on Fiji.
32. Bài 32
When evolution runs backwards
Evolution isn’t supposed to run backwards - yet an increasing number of examples show that it does and that it can sometimes represent the future of a species.
The description of any animal as an ‘evolutionary throwback’ is controversial. For the better part of a century, most biologists have been reluctant to use those words, mindful of a principle of evolution that says ‘evolution cannot run backwards. But as more and more examples come to light and modern genetics enters the scene, that principle is having to be rewritten. Not only are evolutionary throwbacks possible, they sometimes play an important role in the forward march of evolution.
The technical term for an evolutionary throwback is an ‘atavism’, from the Latin atavus, meaning forefather. The word has ugly connotations thanks largely to Cesare Lombroso, a 19th-century Italian medic who argued that criminals were born not made and could be identified by certain physical features that were throwbacks to a primitive, sub-human state.
While Lombroso was measuring criminals, a Belgian palaeontologist called Louis Dollo was studying fossil records and coming to the opposite conclusion. In 1890 he proposed that evolution was irreversible: that ‘an organism is unable to return, even partially, to a previous stage already realised in the ranks of its ancestors. Early 20th-century biologists came to a similar conclusion, though they qualified it in terms of probability, stating that there is no reason why evolution cannot run backwards - it is just very unlikely. And so the idea of irreversibility in evolution stuck and came to be known as ‘Dollo’s law.
If Dollo’s law is right, atavisms should occur only very rarely, if at all. Yet almost since the idea took root, exceptions have been cropping up. In 1919, for example, a humpback whale with a pair of leglike appendages over a metre long, complete with a full set of limb bones, was caught off Vancouver Island in Canada. Explorer Roy Chapman Andrews argued at the time that the whale must be a throwback to a land-living ancestor. ‘I can see no other explanation, he wrote in 1921.
Since then, so many other examples have been discovered that it no longer makes sense to say that evolution is as good as irreversible. And this poses a puzzle: how can characteristics that disappeared millions of years ago suddenly reappear? In 1994, Rudolf Raff and colleagues at Indiana University in the USA decided to use genetics to put a number on the probability of evolution going into reverse. They reasoned that while some evolutionary changes involve the loss of genes and are therefore irreversible, others may be the result of genes being switched off. If these silent genes are somehow switched back on, they argued, long lost traits could reappear.
Raff’s team went on to calculate the likelihood of it happening. Silent genes accumulate random mutations, they reasoned, eventually rendering them useless. So how long can a gene survive in a species if it is no longer used? The team calculated that there is a good chance of silent genes surviving for up to 6 million years in at least a few individuals in a population, and that some might survive as long as 10 million years. In other words, throwbacks are possible, but only to the relatively recent evolutionary past.
As a possible example, the team pointed to the mole salamanders of Mexico and California. Like most amphibians these begin life in a juvenile ‘tadpole’ state, then metamorphose into the adult form – except for one species, the axolotl, which famously lives its entire life as a juvenile. The simplest explanation for this is that the axolotl lineage alone lost the ability to metamorphose, while others retained it. From a detailed analysis of the salamanders’ family tree, however, it is clear that the other lineages evolved from an ancestor that itself had lost the ability to metamorphose. In other words, metamorphosis in mole salamanders is an atavism. The salamander example fits with Raff’s 10million-year time frame.
More recently, however, examples have been reported that break the time limit, suggesting that silent genes may not be the whole story. In a paper published last year, biologist Gunter Wagner of Yale University reported some work on the evolutionary history of a group of South American lizards called Bachia. Many of these have minuscule limbs; some look more like snakes than lizards and a few have completely lost the toes on their hind limbs. Other species, however, sport up to four toes on their hind legs. The simplest explanation is that the toed lineages never lost their toes, but Wagner begs to differ. According to his analysis of the Bachia family tree, the toed species re-evolved toes from toeless ancestors and, what is more, digit loss and gain has occurred on more than one occasion over tens of millions of years.
So what’s going on? One possibility is that these traits are lost and then simply reappear, in much the same way that similar structures can independently arise in unrelated species, such as the dorsal fins of sharks and killer whales. Another more intriguing possibility is that the genetic information needed to make toes somehow survived for tens or perhaps hundreds of millions of years in the lizards and was reactivated. These atavistic traits provided an advantage and spread through the population, effectively reversing evolution.
But if silent genes degrade within 6 to million years, how can long-lost traits be reactivated over longer timescales? The answer may lie in the womb. Early embryos of many species develop ancestral features. Snake embryos, for example, sprout hind limb buds. Later in development these features disappear thanks to developmental programs that say ‘lose the leg’. If for any reason this does not happen, the ancestral feature may not disappear, leading to an atavism.
Choose the correct letter, A, B, C or D. Write the correct letter in boxes 27-31 on your answer sheet.
27. When discussing the theory developed by Louis Dollo, the writer says that
A. it was immediately referred to as Dollo’s law.
B. it supported the possibility of evolutionary throwbacks.
C. it was modified by biologists in the early twentieth century.
D. it was based on many years of research.
28. The humpback whale caught off Vancouver Island is mentioned because of
A. the exceptional size of its body.
B. the way it exemplifies Dollo’s law.
C. the amount of local controversy it caused.
D. the reason given for its unusual features.
29. What is said about ‘silent genes’?
A. Their numbers vary according to species.
B. Raff disagreed with the use of the term.
C. They could lead to the re-emergence of certain characteristics.
D. They can have an unlimited life span.
30. The writer mentions the mole salamander because
A. it exemplifies what happens in the development of most amphibians.
B. it suggests that Raffs theory is correct.
C. it has lost and regained more than one ability.
D. its ancestors have become the subject of extensive research.
31. Which of the following does Wagner claim?
A. Members of the Bachia lizard family have lost and regained certain features several times.
B. Evidence shows that the evolution of the Bachia lizard is due to the environment.
C. His research into South American lizards supports Raffs assertions.
D. His findings will apply to other species of South American lizards.
Complete each sentence with the correct ending, A-G, below. Write the correct letter, A-G, in boxes 32-36 on your answer sheet.
32. For a long time biologists rejected
33. Opposing views on evolutionary throwbacks are represented by
34. Examples of evolutionary throwbacks have led to
35. The shark and killer whale are mentioned to exemplify
36. One explanation for the findings of Wagner’s research is
A. the question of how certain long-lost traits could reappear.
B. the occurrence of a particular feature in different species.
C. parallels drawn between behaviour and appearance.
D. the continued existence of certain genetic information.
E. the doubts felt about evolutionary throwbacks.
F. the possibility of evolution being reversible.
G. Dollo's findings and the convictions held by Lombroso.
Questions 37 – 40
Do the following statements agree with the claims of the writer in Reading Passage 3? In boxes 37 – 40 on your answer sheet, write:
YES if the statement agrees with the claims of the writer
NO if the statement contradicts the claims of the writer
NOT GIVEN if it is impossible to say what the writer thinks about this
37. Wagner was the first person to do research on South American lizards.
38. Wagner believes that Bachia lizards with toes had toeless ancestors.
39. The temporary occurrence of long-lost traits in embryos is rare.
40. Evolutionary throwbacks might be caused by developmental problems in the womb.
33. Bài 33
KAURI GUM - a piece of New Zealand's history
A. The kauri tree is a massive forest tree native to New Zealand. Kauri once formed vast forests over much of the north of the country. Whereas now it is the wood of the kauri which is an important natural resource, in the past it was the tree's sap (the thick liquid which flows inside a tree) which, when hardened into gum, played an important role in New Zealand's early history.
After running from rips or tears in the bark of trees, the sap hardens to form the lumps of gum which eventually fall to the ground and are buried under layers of forest litter. The bark often splits where branches fork from the trunk, and gum accumulates there also.
The early European settlers in New Zealand collected and sold the gum. Gum fresh from the tree was soft and of low value but most of the gum which was harvested had been buried for thousands of years. This gum came in a bewildering variety of colours, degree of transparency and hardness, depending on the length and location of burial, as well as the health of the original tree and the area of the bleeding. Highest quality gum was hard and bright and was usually found at shallow depth on the hills. Lowest quality gum was soft, black or chalky and sugary and was usually found buried in swamps, where it had been in contact with water for a long time. Long periods in the sun or bush fires could transform dull, cloudy lumps into higher quality transparent gum.
B. Virtually all kauri gum was found in the regions of New Zealand where kauri forests grow today - from the middle of the North Island northwards. In Maori and early European times up until 1850, most gum collected was simply picked up from the ground, but, after that, the majority was recovered by digging.
C. The original inhabitants of New Zealand, the Maori, had experimented with kauri gum well before Europeans arrived at the beginning of the nineteenth century. They called it kapia, and found it of considerable use.
Fresh gum from trees was prized for its chewing quality, as was buried gum when softened in water and mixed with the juice of a local plant. A piece of gum was often passed around from mouth to mouth when people gathered together until it was all gone, or when they tired of chewing, it was laid aside for future use.
Kauri gum burns readily and was used by Maori people to light fires. Sometimes it was bound in grass, ignited and used as a torch by night fishermen to attract fish.
D. The first kauri gum to be exported from New Zealand was part of a cargo taken back to Australia and England by two early expeditions in 1814 and 1815. By the 1860s, kauri gum's reputation was well established in the overseas markets and European immigrants were joining the Maoris in collecting gum on the hills of northern New Zealand. As the surface gum became more scarce, spades were used to dig up the buried ‘treasure’. The increasing number of diggers resulted in rapid growth of the kauri gum exports from 1,000 tons in 1860 to a maximum of over 10,000 tons in 1900.
For fifty years from about 1870 to 1920, the kauri gum industry was a major source of income for settlers in northern New Zealand. As these would-be farmers struggled to break in the land, many turned to gum-digging to earn enough money to support their families and pay for improvements to their farms until better times arrived. By the 1890s, there were 20,000 people engaged in gum-digging. Although many of these, such as farmers, women and children, were only part-time diggers, nearly 7,000 were full-timers. During times of economic difficulty, gum-digging was the only job available where the unemployed from many walks of life could earn a living, if they were prepared to work.
E. The first major commercial use of kauri gum was in the manufacture of high-grade furniture varnish, a kind of clear paint used to treat wood. The best and purest gum that was exported prior to 1910 was used in this way. Kauri gum was used in 70% of the oil varnishes being manufactured in England in the 1890s. It was favoured ahead of other gums because it was easier to process at lower temperatures. The cooler the process could be kept the better, as it meant a paler varnish could be produced.
About 1910, kauri gum was found to be a very suitable ingredient in the production of some kinds of floor coverings such as linoleum. In this way, a use was found for the vast quantities of poorer quality and less pure gum, that had up till then been discarded as waste. Kauri gum's importance in the manufacture of varnish and linoleum was displaced by synthetic alternatives in the 1930s.
F. Fossil kauri gum is rather soft and can be carved easily with a knife or polished with fine sandpaper. In the time of Queen Victoria of England (1837-1901), some pieces were made into fashionable amber beads that women wore around their necks. The occasional lump that contained preserved insects was prized for use in necklaces and bracelets. Many of the gum-diggers enjoyed the occasional spell of carving and produced a wide variety of small sculptured pieces. Many of these carvings can be seen today in local museums.
Over the years, kauri gum has also been used in a number of minor products, such as an ingredient in marine glue and candles. In the last decades, it has had a very limited use in the manufacture of extremely high-grade varnish for violins, but the gum of the magnificent kauri tree remains an important part of New Zealand's history.
The text has six sections A-F.
Which section contains the following information?
Write the correct letter, A-F, in boxes 28-33 on your answer sheet.
NB You may use any letter more than once.
28. an example of a domestic product made of high-quality gum
29. factors affecting gum quality
30. how kauri gum is formed
31. how gum was gathered
32. the main industrial uses of the gum
33. recent uses of kauri gum
Look at the following events in the history of kauri gum in New Zealand (Questions 34-39) and the list of time periods below. Match each event with the correct time period, A-I. Write the correct letter, A-I, in boxes 34-39 on your answer sheet.
34. Kauri gum was first used in New Zealand.
35. The amount of kauri gum sent overseas peaked.
36. The collection of kauri gum supplemented farmers' incomes.
37. Kauri gum was made into jewellery.
38. Kauri gum was used in the production of string instruments.
39. Most of the kauri gum was found underground.
List of Time Period
A. before the 1800s
B. in 1900
C. in 1910
D. between the late 1800s and the early 1900s
E. between the 1830s and 1900
F. in 1814 and 1815
G. after 1850
H. in the 1930s
I. in recent times
Choose the correct letter, A, B, C or D. Write the correct letter in box 40 on your answer sheet.
40. What was most likely to reduce the quality of kauri gum?
A. how long it was buried
B. exposure to water
C. how deep it was buried
D. exposure to heat
34. Bài 34
By the year 2050, nearly 80% of the Earth’s population will live in urban centres. Applying the most conservative estimates to current demographic trends, the human population will increase by about three billion people by then. An estimated 109 hectares of new land (about 20% larger than Brazil) will be needed to grow enough food to feed them, if traditional farming methods continue as they are practised today. At present, throughout the world, over 80% of the land that is suitable for raising crops is in use. Historically, some 15% of that has been laid waste by poor management practices. What can be done to ensure enough food for the world’s population to live on?
The concept of indoor farming is not new, since hothouse production of tomatoes and other produce has been in vogue for some time. What is new is the urgent need to scale up this technology to accommodate another three billion people. Many believe an entirely new approach to indoor farming is required, employing cutting-edge technologies. One such proposal is for the “Vertical Farm”. The concept is of multi-storey buildings in which food crops are grown in environmentally controlled conditions. Situated in the heart of urban centres, they would drastically reduce the amount of transportation required to bring food to consumers. Vertical farms would need to be efficient, cheap to construct and safe to operate. If successfully implemented, proponents claim, vertical farms offer the promise of urban renewal, sustainable production of a safe and varied food supply (through year-round production of all crops), and the eventual repair of ecosystems that have been sacrificed for horizontal farming.
It took humans 10,000 years to learn how to grow most of the crops we now take for granted. Along the way, we despoiled most of the land we worked, often turning verdant, natural ecozones into semi-arid deserts. Within that same time frame, we evolved into an urban species, in which 60% of the human population now lives vertically in cities. This means that, for the majority, we humans have shelter from the elements, yet we subject our food-bearing plants to the rigours of the great outdoors and can do no more than hope for a good weather year. However, more often than not now, due to a rapidly changing climate, that is not what happens. Massive floods, long droughts, hurricanes and severe monsoons take their toll each year, destroying millions of tons of valuable crops.
The supporters of vertical farming claim many potential advantages for the system. For instance, crops would be produced all year round, as they would be kept in artificially controlled, optimum growing conditions. There would be no weather-related crop failures due to droughts, floods or pests. All the food could be grown organically, eliminating the need for herbicides, pesticides and fertilisers. The system would greatly reduce the incidence of many infectious diseases that are acquired at the agricultural interface. Although the system would consume energy, it would return energy to the grid via methane generation from composting non-edible parts of plants. It would also dramatically reduce fossil fuel use, by cutting out the need for tractors, ploughs and shipping.
A major drawback of vertical farming, however, is that the plants would require artificial light. Without it, those plants nearest the windows would be exposed to more sunlight and grow more quickly, reducing the efficiency of the system. Single-storey greenhouses have the benefit of natural overhead light: even so, many still need artificial lighting. A multi-storey facility with no natural overhead light would require far more. Generating enough light could be prohibitively expensive, unless cheap, renewable energy is available, and this appears to be rather a future aspiration than a likelihood for the near future.
One variation on vertical farming that has been developed is to grow plants in stacked trays that move on rails. Moving the trays allows the plants to get enough sunlight. This system is already in operation, and works well within a single-storey greenhouse with light reaching it from above: it is not certain, however, that it can be made to work without that overhead natural light.
Vertical farming is an attempt to address the undoubted problems that we face in producing enough food for a growing population. At the moment, though, more needs to be done to reduce the detrimental impact it would have on the environment, particularly as regards the use of energy. While it is possible that much of our food will be grown in skyscrapers in future, most experts currently believe it is far more likely that we will simply use the space available on urban rooftops.
Complete the sentences below. Choose NO MORE THAN TWO WORDS from the passage for each answer. Write your answers in boxes 1-7 on your answer sheet.
1. Some food plants, including ……………………….. are already grown indoors.
2. Vertical farms would be located in ……………………….., meaning that there would be less need to take them long distances to customers.
3. Vertical farms could use methane from plants and animals to produce ………………………...
4. The consumption of ……………………….. would be cut because agricultural vehicles would be unnecessary.
5. The fact that vertical farms would need ……………………….. light is a disadvantage.
6. One form of vertical farming involves planting in ……………………….. which are not fixed.
7. The most probable development is that food will be grown on ……………………….. in towns and cities.
Do the following statements agree with the information given in Reading Passage 1? In boxes 8-13 on your answer sheet, write:
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this
8. Methods for predicting the Earth’s population have recently changed.
9. Human beings are responsible for some of the destruction to food-producing land.
10. The crops produced in vertical farms will depend on the season.
11. Some damage to food crops is caused by climate change.
12. Fertilisers will be needed for certain crops in vertical farms.
13. Vertical farming will make plants less likely to be affected by infectious diseases.
35. Bài 35
Reducing the Effects of Climate Change
Mark Rowe reports on the increasingly ambitious geo-engineering projects being explored by scientists
A. Such is our dependence on fossil fuels, and such is the volume of carbon dioxide already released into the atmosphere, that many experts agree that significant global warming is now inevitable. They believe that the best we can do is keep it at a reasonable level, and at present, the only serious option for doing this is cutting back on our carbon emissions. But while a few countries are making major strides in this regard, the majority are having great difficulty even stemming the rate of increase, let alone reversing it. Consequently, an increasing number of scientists are beginning to explore the alternative of geo-engineering — a term which generally refers to the intentional large-scale manipulation of the environment. According to its proponents, geo-engineering is the equivalent of a backup generator: if Plan A - reducing our dependency on fossil fuels - fails, we require a Plan B, employing grand schemes to slow down or reverse the process of global warming.
B. Geo-engineering; has been shown to work, at least on a small localised scale. For decades, MayDay parades in Moscow have taken place under clear blue skies, aircraft having deposited dry ice, silver iodide and cement powder to disperse clouds. Many of the schemes now suggested look to do the opposite, and reduce the amount of sunlight reaching the planet. The most eye-catching idea of all is suggested by Professor Roger Angel of the University of Arizona. His scheme would employ up to 16 trillion minute spacecraft, each weighing about one gram, to form a transparent, sunlight-refracting sunshade in an orbit 1.5 million km above the Earth. This could, argues Angel, reduce the amount of light reaching the Earth by two per cent.
C. The majority of geo-engineering projects so far carried out — which include planting forests in deserts and depositing iron in the ocean to stimulate the growth of algae - have focused on achieving a general cooling of the Earth. But some look specifically at reversing the melting at the poles, particularly the Arctic. The reasoning is that if you replenish the ice sheets and frozen waters of the high latitudes, more light will be reflected back into space, so reducing the warming of the oceans and atmosphere.
D. The concept of releasing aerosol sprays into the stratosphere above the Arctic has been proposed by several scientists. This would involve using sulphur or hydrogen sulphide aerosols so that sulphur dioxide would form clouds, which would, in turn, lead to a global dimming. The idea is modelled on historic volcanic explosions, such as that of Mount Pinatubo in the Philippines in 1991, which led to a short-term cooling of global temperatures by 0.5 °C. Scientists have also scrutinised whether it's possible to preserve the ice sheets of Greenland with reinforced high-tension cables, preventing icebergs from moving into the sea. Meanwhile, in the Russian Arctic, geo-engineering plans include the planting of millions of birch trees. Whereas the regions native evergreen pines shade the snow and absorb radiation, birches would shed their leaves in winter, thus enabling radiation to be reflected by the snow. Re-routing Russian rivers to increase cold water flow to ice-forming areas could also be used to slow down warming, say some climate scientists.
E. But will such schemes ever be implemented? Generally speaking, those who are most cautious about geo-engineering are the scientists involved in the research. Angel says that his plan is ‘no substitute for developing renewable energy: the only permanent solution'. And Dr Phil Rasch of the US-based Pacific Northwest National Laboratory is equally guarded about the role of geo-engineering: 'I think all of us agree that if we were to end geo-engineering on a given day, then the planet would return to its pre-engineered condition very rapidly, and probably within ten to twenty years. That’s certainly something to worry about.’
F. The US National Center for Atmospheric Research has already suggested that the proposal to inject sulphur into the atmosphere might affect rainfall patterns across the tropics and the Southern Ocean. ‘Geo-engineering plans to inject stratospheric aerosols or to seed clouds would act to cool the planet, and act to increase the extent of sea ice,’ says Rasch. ‘But all the models suggest some impact on the distribution of precipitation.’
G. A further risk with geo-engineering projects is that you can “overshoot Y says Dr Dan Hunt, from the University of Bristol’s School of Geophysical Sciences, who has studied the likely impacts of the sunshade and aerosol schemes on the climate. ‘You may bring global temperatures back to pre-industrial levels, but the risk is that the poles will still be warmer than they should be and the tropics will be cooler than before industrialisation.’To avoid such a scenario,” Hunt says, “Angel’s project would have to operate at half strength; all of which reinforces his view that the best option is to avoid the need for geo-engineering altogether.”
H. The main reason why geo-engineering is supported by many in the scientific community is that most researchers have little faith in the ability of politicians to agree — and then bring in — the necessary carbon cuts. Even leading conservation organisations see the value of investigating the potential of geo-engineering. According to Dr Martin Sommerkorn, climate change advisor for the World Wildlife Fund’s International Arctic Programme, ‘Human-induced climate change has brought humanity to a position where we shouldn’t exclude thinking thoroughly about this topic and its possibilities.’
Reading Passage 3 has eight paragraphs A-H.
Which paragraph contains the following information?
Write the correct letter, A-H, in boxes 27-29 on your answer sheet.
27. mention of a geo-engineering project based on an earlier natural phenomenon
28. an example of a successful use of geo-engineering
29. a common definition of geo-engineering
Complete the table below. Choose ONE WORD from the passage for each answer. Write your answers in boxes 30-36 on your answer sheet.
Look at the following statements (Questions 37-40) and the list of scientists below. Match each statement with the correct scientist, A-D. Write the correct letter, A-D, in boxes 37-40 on your answer sheet.
37. The effects of geo-engineering may not be long-lasting.
38. Geo-engineering is a topic worth exploring.
39. It may be necessary to limit the effectiveness of geo-engineering projects.
40. Research into non-fossil-based fuels cannot be replaced by geo-engineering.
List of Scientists
A. Roger Angel
B. Phil Rasch
C. Dan Lunt
D. Martin Sommerkorn
36. Bài 36
Reading Passage 2 has seven paragraphs, A-G. Choose the correct heading for each paragraph from the list of headings below. Write the correct number, i-ix, in boxes 14-20 on your answer sheet.
List of Headings
i. Evidence of innovative environment management practices
ii. An undisputed answer to a question about the moai
iii. The future of the moai statues
iv. A theory which supports a local belief
v. The future of Easter Island
vi. Two opposing views about the Rapanui people
vii. Destruction outside the inhabitants’ control
viii. How the statues made a situation worse
ix. Diminishing food resources
14. Paragraph A
15. Paragraph B
16. Paragraph C
17. Paragraph D
18. Paragraph E
19. Paragraph F
20. Paragraph G
What destroyed the civilisation of Easter Island?
A. Easter Island, or Rapu Nui as it is known locally, is home to several hundred ancient human statues - the moai. After this remote Pacific island was settled by the Polynesians, it remained isolated for centuries. All the energy and resources that went into the moai - some of which are ten metres tall and weigh over 7,000 kilos - came from the island itself. Yet when Dutch explorers landed in 1722, they met a Stone Age culture. The moai were carved with stone tools, then transported for many kilometres, without the use of animals or wheels, to massive stone platforms. The identity of the moai builders was in doubt until well into the twentieth century. Thor Heyerdahl, the Norwegian ethnographer and adventurer, thought the statues had been created by pre-Inca peoples from Peru. Bestselling Swiss author Erich von Daniken believed they were built by stranded extraterrestrials. Modern science - linguistic, archaeological and genetic evidence - has definitively proved the moai builders were Polynesians, but not how they moved their creations. Local folklore maintains that the statues walked, while researchers have tended to assume the ancestors dragged the statues somehow, using ropes and logs.
B. When the Europeans arrived, Rapa Nui was grassland, with only a few scrawny trees. In the 1970s and 1980s, though, researchers found pollen preserved in lake sediments, which proved the island had been covered in lush palm forests for thousands of years. Only after the Polynesians arrived did those forests disappear. US scientist Jared Diamond believes that the Rapanui people - descendants of Polynesian settlers - wrecked their own environment. They had unfortunately settled on an extremely fragile island - dry, cool, and too remote to be properly fertilised by windblown volcanic ash. When the islanders cleared the forests for firewood and farming, the forests didn’t grow back. As trees became scarce and they could no longer construct wooden canoes for fishing, they ate birds. Soil erosion decreased their crop yields. Before Europeans arrived, the Rapanui had descended into civil war and cannibalism, he maintains. The collapse of their isolated civilisation, Diamond writes, is a ’worst-case scenario for what may lie ahead of us in our own future’.
C. The moai, he thinks, accelerated the self-destruction. Diamond interprets them as power displays by rival chieftains who, trapped on a remote little island, lacked other ways of asserting their dominance. They competed by building ever bigger figures. Diamond thinks they laid the moai on wooden sledges, hauled over log rails, but that required both a lot of wood and a lot of people. To feed the people, even more land had to be cleared. When the wood was gone and civil war began, the islanders began toppling the moai. By the nineteenth century none were standing.
D. Archaeologists Terry Hunt of the University of Hawaii and Carl Lipo of California State University agree that Easter Island lost its lush forests and that it was an ‘ecological catastrophe' - but they believe the islanders themselves weren’t to blame. And the moai certainly weren’t. Archaeological excavations indicate that the Rapanui went to heroic efforts to protect the resources of their wind-lashed, infertile fields. They built thousands of circular stone windbreaks and gardened inside them, and used broken volcanic rocks to keep the soil moist. In short, Hunt and Lipo argue, the prehistoric Rapanui were pioneers of sustainable farming.
E. Hunt and Lipo contend that moai-building was an activity that helped keep the peace between islanders. They also believe that moving the moai required few people and no wood, because they were walked upright. On that issue, Hunt and Lipo say, archaeological evidence backs up Rapanui folklore. Recent experiments indicate that as few as 18 people could, with three strong ropes and a bit of practice, easily manoeuvre a 1,000 kg moai replica a few hundred metres. The figures’ fat bellies tilted them forward, and a D-shaped base allowed handlers to roll and rock them side to side.
F. Moreover, Hunt and Lipo are convinced that the settlers were not wholly responsible for the loss of the island’s trees. Archaeological finds of nuts from the extinct Easter Island palm show tiny grooves, made by the teeth of Polynesian rats. The rats arrived along with the settlers, and in just a few years, Hunt and Lipo calculate, they would have overrun the island. They would have prevented the reseeding of the slow-growing palm trees and thereby doomed Rapa Nui’s forest, even without the settlers’ campaign of deforestation. No doubt the rats ate birds’ eggs too. Hunt and Lipo also see no evidence that Rapanui civilisation collapsed when the palm forest did. They think its population grew rapidly and then remained more or less stable until the arrival of the Europeans, who introduced deadly diseases to which islanders had no immunity. Then in the nineteenth century slave traders decimated the population, which shrivelled to 111 people by 1877.
G. Hunt and Lipo’s vision, therefore, is one of an island populated by peaceful and ingenious moai builders and careful stewards of the land, rather than by reckless destroyers ruining their own environment and society. ‘Rather than a case of abject failure, Rapu Nui is an unlikely story of success’, they claim. Whichever is the case, there are surely some valuable lessons which the world at large can learn from the story of Rapa Nui.
Complete the summary below. Choose ONE WORD ONLY from the passage for each answer. Write your answers in boxes 21-24 on your answer sheet.
Jared Diamond’s View
Diamond believes that the Polynesian settlers on Rapa Nui destroyed its forests, cutting down its trees for fuel and clearing land for 21 .................... Twentieth-century discoveries of pollen prove that Rapu Nui had once been covered in palm forests, which had turned into grassland by the time the Europeans arrived on the island. When the islanders were no longer able to build the 22 .................... they needed to go fishing, they began using the island’s 23 .................... as a food source, according to Diamond. Diamond also claims that the moai were built to show the power of the island’s chieftains, and that the methods of transporting the statues needed not only a great number of people, but also a great deal of 24 .................... .
Questions 25 and 26
Choose TWO letters, A-E. Write the correct letters in boxes 25 and 26 on your answer sheet.
On what points do Hunt and Lipo disagree with Diamond?
A. the period when the moai were created
B. how the moai were transported
C. the impact of the moai on Rapanui society
D. how the moai were carved
E. the origins of the people who made the moai
37. Bài 37
Animal migration, however it is defined, is far more than just the movement of animals. It can loosely be described as travel that takes place at regular intervals - often in an annual cycle - that may involve many members of a species, and is rewarded only after a long journey. It suggests inherited instinct. The biologist Hugh Dingle has identified five characteristics that apply, in varying degrees and combinations, to all migrations. They are prolonged movements that carry animals outside familiar habitats; they tend to be linear, not zigzaggy; they involve special behaviours concerning preparation (such as overfeeding) and arrival; they demand special allocations of energy. And one more: migrating animals maintain an intense attentiveness to the greater mission, which keeps them undistracted by temptations and undeterred by challenges that would turn other animals aside.
An arctic tern, on its 20,000 km flight from the extreme south of South America to the Arctic circle, will take no notice of a nice smelly herring offered from a bird-watcher's boat along the way. While local gulls will dive voraciously for such handouts, the tern flies on. Why? The arctic tern resists distraction because it is driven at that moment by an instinctive sense of something we humans find admirable: larger purpose. In other words, it is determined to reach its destination. The bird senses that it can eat, rest and mate later. Right now it is totally focused on the journey; its undivided intent is arrival.
Reaching some gravelly coastline in the Arctic, upon which other arctic terns have converged, will serve its larger purpose as shaped by evolution: finding a place, a time, and a set of circumstances in which it can successfully hatch and rear offspring.
But migration is a complex issue, and biologists define it differently, depending in part on what sorts of animals they study. Joe! Berger, of the University of Montana, who works on the American pronghorn and other large terrestrial mammals, prefers what he calls a simple, practical definition suited to his beasts: 'movements from a seasonal home area away to another home area and back again'. Generally, the reason for such seasonal back-and-forth movement is to seek resources that aren't available within a single area year-round.
But daily vertical movements by zooplankton in the ocean - upward by night to seek food, downward by day to escape predators - can also be considered migration. So can the movement of aphids when, having depleted the young leaves on one food plant, their offspring then fly onward to a different host plant, with no one aphid ever returning to where it started.
Dingle is an evolutionary biologist who studies insects. His definition is more intricate than Berger's, citing those five features that distinguish migration from other forms of movement. They allow for the fact that, for example, aphids will become sensitive to blue light (from the sky) when it's time for takeoff on their big journey, and sensitive to yellow light (reflected from tender young leaves) when it's appropriate to land. Birds will fatten themselves with heavy feeding in advance of a long migrational flight. The value of his definition, Dingle argues, is that it focuses attention on what the phenomenon of wildebeest migration shares with the phenomenon of the aphids, and therefore helps guide researchers towards understanding how evolution has produced them all.
Human behaviour, however, is having a detrimental impact on animal migration. The pronghorn, which resembles an antelope, though they are unrelated, is the fastest land mammal of the New World. One population, which spends the summer in the mountainous Grand Teton National Park of the western USA, follows a narrow route from its summer range in the mountains, across a river, and down onto the plains. Here they wait out the frozen months, feeding mainly on sagebrush blown clear of snow. These pronghorn are notable for the invariance of their migration route and the severity of its construction at three bottlenecks. If they can't pass through each of the three during their spring migration, they can't reach their bounty of summer grazing; if they can't pass through again in autumn, escaping south onto those windblown plains, they are likely to die trying to overwinter in the deep snow. Pronghorn, dependent on distance vision and speed to keep safe from predators, traverse high, open shoulders of land, where they can see and run. At one of the bottlenecks, forested hills rise to form a V, leaving a corridor of open ground only about 150 metres wide, filled with private homes. Increasing development is leading toward a crisis for the pronghorn, threatening to choke off their passageway.
Conservation scientists, along with some biologists and land managers within the USA's National Park Service and other agencies, are now working to preserve migrational behaviours, not just species and habitats. A National Forest has recognised the path of the pronghorn, much of which passes across its land, as a protected migration corridor. But neither the Forest Service nor the Park Service can control what happens on private land at a bottleneck. And with certain other migrating species, the challenge is complicated further - by vastly greater distances traversed, more jurisdictions, more borders, more dangers along the way. We will require wisdom and resoluteness to ensure that migrating species can continue their journeying a while longer.
Do the following statements agree with the information given in Reading Passage 2? In boxes 14-18 on your answer sheet, write:
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this
14. Local gulls and migrating arctic terns behave in the same way when offered food.
15. Experts’ definitions of migration tend to vary according to their area of study.
16. Very few experts agree that the movement of aphids can be considered migration.
17. Aphids’ journeys are affected by changes in the light that they perceive.
18. Dingle's aim is to distinguish between the migratory behaviours of different species.
Complete each sentence with the correct ending, A-G, below. Write the correct letter, A-G. in boxes 19-22 on your answer sheet
19. According to Dingle, migratory routes are likely to
20. To prepare for migration, animals are likely to
21. During migration, animals are unlikely to
22. Arctic terns illustrate migrating animals’ ability to
A. be discouraged by difficulties.
B. travel on open land where they can look out for predators.
C. eat more than they need for immediate purposes.
D. be repeated daily.
E. ignore distractions.
F. be governed by the availability of water.
G. follow a straight line.
Complete the summary below. Choose ONE WORD ONLY from the passage for each answer. Write your answers in boxes 23-26 on your answer sheet.
The migration of pronghorns
Pronghorns rely on their eyesight and 23 .................. to avoid predators. One particular population’s summer habitat is a national park, and their winter home is on the 24 .................. where they go to avoid the danger presented by the snow at that time of year. However, their route between these two areas contains three 25 .................. . One problem is the construction of new homes in a narrow 26 .................. of land on the pronghorns’ route.
38. Bài 38
The risks agriculture faces in developing countries
Synthesis of an online debate*
A. Two things distinguish food production from all other productive activities: first, every single person needs food each day and has a right to it; and second, it is hugely dependent on nature. These two unique aspects, one political, the other natural, make food production highly vulnerable and different from any other business. At the same time, cultural values are highly entrenched in food and agricultural systems worldwide.
B. Farmers everywhere face major risks; including extreme weather, long-term climate change, and price volatility in input and product markets. However, smallholder farmers in developing countries must in addition deal with adverse environments, both natural, in terms of soil quality, rainfall, etc. and human, in terms of infrastructure, financial systems, markets, knowledge and technology. Counter-intuitively, hunger is prevalent among many smallholder farmers in the developing world.
C. Participants in the online debate argued that our biggest challenge is to address the underlying causes of the agricultural system’s inability to ensure sufficient food for all, and they identified as drivers of this problem our dependency on fossil fuels and unsupportive government policies.
D. On the question of mitigating the risks farmers face, most essayists called for greater state intervention. In his essay, Kanayo F. Nwanze, President of the International Fund for Agricultural Development, argued that governments can significantly reduce risks for farmers by providing basic services like roads to get produce more efficiently to markets, or water and food storage facilities to reduce losses. Sophia Murphy, senior advisor to the Institute for Agriculture and Trade Policy, suggested that the procurement and holding of stocks by governments can also help mitigate wild swings in food prices by alleviating uncertainties about market supply.
E. Shenggen Fan, Director General of the International Food Policy Research Institute, held up social safety nets and public welfare programmes in Ethiopia, Brazil and Mexico as valuable ways to address poverty among farming families and reduce their vulnerability to agriculture shocks. However, some commentators responded that cash transfers to poor families do not necessarily translate into increased food security, as these programmes do not always strengthen food production or raise incomes.
Regarding state subsidies for agriculture, Rokeya Kabir, Executive Director of Bangladesh Nari Progati Sangha, commented in her essay that these ‘have not compensated for the stranglehold exercised by private traders.
In fact, studies show that sixty percent of beneficiaries of subsidies are not poor, but rich landowners and non-farmer traders.
F. Nwanze, Murphy and Fan argued that private risk management tools, like private insurance, commodity futures markets, and rural finance can help small-scale producers mitigate risk and allow for investment in improvements. Kabir warned that financial support schemes often encourage the adoption of high-input agricultural practices, which in the medium term may raise production costs beyond the value of their harvests.
Murphy noted that when futures markets become excessively financialised they can contribute to short-term price volatility, which increases farmers’ food insecurity. Many participants and commentators emphasised that greater transparency in markets is needed to mitigate the impact of volatility, and make evident whether adequate stocks and supplies are available. Others contended that agribusiness companies should be held responsible for paying for negative side effects.
G. Many essayists mentioned climate change and its consequences for small-scale agriculture. Fan explained that in addition to reducing crop yields, climate change increases the magnitude and the frequency of extreme weather events, which increase smallholder vulnerability. The growing unpredictability of weather patterns increases farmers’ difficulty in managing weather-related risks.
According to this author, one solution would be to develop crop varieties that are more resilient to new climate trends and extreme weather patterns. Accordingly, Pat Mooney, co-founder and executive director of the ETC Group, suggested that ‘if we are to survive climate change, we must adopt policies that let peasants diversify the plant and animal species and varieties/breeds that make up our menus.
H. Some participating authors and commentators argued in favour of community- based and autonomous risk management strategies through collective action groups, co-operatives or producers’ groups. Such groups enhance market opportunities for small-scale producers, reduce marketing costs and synchronise buying and selling with seasonal price conditions.
According to Murphy, ‘collective action offers an important way for farmers to strengthen their political and economic bargaining power, and to reduce their business risks. One commentator, Giel Ton, warned that collective action does not come as a free good. It takes time, effort and money to organise, build trust and to experiment. Others, like Marcel Vernooij and Marcel Beukeboom, suggested that in order to ‘apply what we already know’, all stakeholders, including business, government, scientists and civil society, must work together, starting at the beginning of the value chain.