Summary, note, table and flow-chart completion

Reading Passage 1 – Hedgerows: Britain's Living Fences

Seen from the air, much of the British countryside resembles a patchwork quilt, its fields stitched together by dark green lines. These lines are hedgerows: narrow belts of shrubs and small trees, often with a bank or ditch alongside, that have marked the edges of fields for centuries. To the casual observer they may look like a natural feature of the landscape, but almost all of them were planted by people, and each one carries a record of the decisions made by those who farmed the land.

Some hedgerows are remarkably old. A few are thought to be the remains of woodland that was cleared on either side, leaving a strip of trees standing as a boundary, and some of these may date back more than a thousand years. Far more, however, are the product of a single period of change. Between roughly 1750 and 1850, a series of Acts of Parliament divided up large areas of open land that had previously been farmed in common. The new private fields needed boundaries, and the cheapest way to create a barrier that would keep in cattle and sheep was to plant hawthorn, a fast-growing shrub whose sharp thorns discourage animals from pushing through. Tens of thousands of kilometres of hawthorn hedge were planted in these years, many of them in straight lines that still distinguish this 'enclosure' landscape from older, more irregular field patterns.

How can anyone tell the age of a hedge? In the 1970s, the ecologist Max Hooper studied hedges whose planting dates were known from historical documents, and noticed a striking relationship: the older the hedge, the more species of woody plant it contained. A newly planted hedge typically consisted of just one or two species, but over time birds and the wind brought in the seeds of others, such as hazel, field maple and holly. Hooper suggested that counting the woody species in a thirty-metre stretch and multiplying by a hundred would give a rough estimate of the hedge's age in years. The method, now known as Hooper's rule, is still widely quoted, although Hooper himself stressed that it was only a rough guide, and later researchers have found that it works poorly in some regions, where hedges were deliberately planted with a mixture of species from the start.

Hedgerows matter for wildlife as much as for history. They provide food, shelter and nesting sites for a great many animals, including birds such as the yellowhammer and mammals such as the hazel dormouse. Perhaps more importantly, they act as corridors: small creatures that would be exposed to predators in an open field can travel safely along a hedge from one patch of woodland to another. Studies of bats have shown that many species navigate by following hedgerows at night, and may abandon a route where a gap of only a few metres appears.

For much of the twentieth century, however, hedgerows were seen as an obstacle to efficient farming. As tractors and combine harvesters became larger, farmers removed hedges to create bigger fields, and government grants were at one time available to help pay for this work. By some estimates, as much as half of the hedgerow in England disappeared in the decades after the Second World War. Many of the hedges that survived were damaged by a different problem: instead of being managed by hand, they were cut every year by machines, which trimmed them into neat boxes but left them thin and full of gaps at the bottom.

Attitudes began to change in the 1990s. In 1997, regulations were introduced in England and Wales that made it illegal to remove most countryside hedgerows without first notifying the local authority, which can refuse permission if a hedge is judged to be important for historical or ecological reasons. Payments are now offered to farmers who plant new hedges or restore old ones, and interest has revived in traditional management techniques such as hedge laying. In this craft, each stem is cut almost all the way through near the ground and then bent over at an angle, so that it continues to grow but forms a dense, living barrier. Annual competitions attract skilled hedge layers from across the country, each region having its own distinctive style.

Whether these efforts are enough remains uncertain. Planting a hedge takes a day; growing one that supports the full range of wildlife found in an ancient boundary takes many decades. Conservationists argue that protecting the hedges that already exist, and managing them less intensively, will achieve far more than planting new ones.

Decline and recovery of hedgerows

20th century

• Hedges removed to make bigger fields for larger machines; the government sometimes provided (8) ______ to cover the cost

• Surviving hedges cut every year by machine, leaving them thin, with (9) ______ near the ground

Since the 1990s

• Before removing most hedges, farmers must inform the local (10) ______

• Hedge laying: each stem is cut almost through and then (11) ______ at an angle

• Competitions show that every region has a different (12) ______

The future

• Conservationists: protect the hedges that exist now and manage them less (13) ______

Reading Passage 2 – Farming Upwards

A At first sight the concept appears to belong to science fiction: lettuces, herbs and strawberries cultivated in tiers inside windowless warehouses, illuminated by pink and blue light and entirely without soil. Over the past fifteen years, however, so-called vertical farms have progressed from architects' sketches to functioning commercial operations. Their advocates portray them as a response to several of agriculture's most persistent difficulties, ranging from the depletion of freshwater resources to the lengthy supply chains on which urban populations depend. The sector's track record, nevertheless, has been strikingly inconsistent: a handful of profitable enterprises coexist with a series of costly and widely reported collapses.

B The underlying technology is relatively straightforward. In the majority of installations, crops are cultivated hydroponically, their roots immersed in a solution of water and dissolved minerals; in others, which rely on a technique termed aeroponics, the roots are left suspended in the air and periodically sprayed with a fine mist. Since the water is captured and recirculated rather than lost through evaporation and drainage, operators maintain that consumption can be as much as 95 per cent lower than on a conventional farm producing an equivalent crop. Because the growing environment is sealed, insects have considerable difficulty gaining access, with the result that pesticides are seldom required. Illumination is supplied by light-emitting diodes (LEDs), and it is here, according to the plant physiologist Professor Ines Duarte, that much of the real ingenuity resides. 'Photosynthesis does not respond equally to every wavelength,' she observes. 'LEDs allow us to tune the spectrum to the requirements of each species at each stage of its development – a degree of control that natural sunlight cannot provide.'

C For food retailers, though, the principal appeal lies less in resource efficiency than in freshness. A field-grown lettuce may spend several days in transit and storage before it is displayed for sale, deteriorating in both flavour and shelf life along the way. A vertical farm, by contrast, can be sited on the periphery of a city or even within it, so that produce picked in the early morning may be on supermarket shelves the same day. 'Consumers are not buying technology,' remarks Marcus Feld, who founded one of the earliest commercial vertical farms in northern Europe. 'What they are buying is a salad that keeps for a week in the fridge rather than three days.' Output is also highly predictable: an indoor facility is insulated from drought, flooding and unseasonal frost, and can therefore supply an identical volume throughout the year.

D The fundamental obstacle is energy. Whereas sunlight costs nothing, electricity does, and every hour of illumination received by an indoor crop must be paid for, as must the cooling required to dissipate the heat generated by the lamps. It is for this reason that vertical farms produce little apart from leafy greens, culinary herbs and a limited range of soft fruit – crops that mature rapidly, are harvested in their entirety and command a comparatively high price per kilogram. Staple cereals such as wheat and rice present an altogether different case. The agricultural economist Dr Hannah Kessler has estimated that the electricity needed to grow enough wheat indoors for a single loaf would cost many times the retail price of the loaf itself. 'For any crop, the decisive question is how much revenue each unit of light can generate,' she argues. 'In the case of basil, a considerable amount; in the case of grain, virtually none.'

E The consequences of these economics became painfully apparent when energy prices rose steeply in the early 2020s. A number of well-capitalised companies, some of which had attracted hundreds of millions of dollars in investment, were obliged to close facilities or file for bankruptcy. Critics contended that, in many instances, business plans had rested on unduly optimistic cost projections and on the assumption that rapid expansion would in itself generate economies of scale. Feld is frank about the industry's misjudgements. 'Many of us, quite simply, designed our operations for an era of cheap power,' he acknowledges. 'Once that era ended, the figures no longer added up.'

F Few commentators now anticipate that vertical farming will supplant conventional agriculture, yet this need not imply that it lacks a future. Some producers are adopting hybrid models, notably greenhouses that exploit natural daylight and activate supplementary LEDs only when sunlight is insufficient. Others are drawing on solar or wind generation, or on surplus heat from neighbouring industrial plants. Duarte, for her part, suspects that the technology's most significant contribution may lie in a different direction entirely. 'Consider polar research stations, cities in arid regions or, eventually, a lunar base,' she suggests. 'Where conventional cultivation is impossible, a vertical farm is under no obligation to compete with a field. It merely has to function.'

How vertical farms work

In a vertical farm, plants grow without soil. Their roots either sit in a nutrient solution or, in aeroponic systems, hang in the air and are regularly coated with a (24) ______. Since insects find it hard to enter the sealed buildings, there is little need for (25) ______. Retailers value the fact that crops can reach stores on the (26) ______ they are harvested.

Reading Passage 2 – Keeping the Same Time

A Before the nineteenth century, few people had any reason to know what time it was anywhere other than in their own town. Time was local: noon was the moment when the sun stood highest in the sky, and because the sun appears to travel from east to west, noon arrived a little later at every place further to the west. A town a hundred kilometres west of another would therefore keep time several minutes behind it. Public clocks on churches and town halls were set by sundials or by astronomical observation, and nobody was troubled by the fact that neighbouring towns disagreed.

B The railways changed this. When journeys that had once taken days could be completed in a few hours, differences of a few minutes began to matter. A passenger reading a timetable needed to know whether a departure time referred to the clock at the station he was leaving or at the one he was travelling to, and staff scheduling trains on a shared line needed a single reference if collisions were to be avoided. In Britain, individual railway companies began to run their trains according to London time, and within a decade most of the country's railways had adopted it.

C This so-called railway time did not win immediate acceptance. Many towns continued to keep their own local time on public clocks, and some clocks were fitted with two minute hands, one showing local time and the other railway time. Critics complained that an arrangement designed for the convenience of commercial companies was being imposed on everyone else. Nevertheless, the practical advantages proved hard to resist, and over the following decades the great majority of public clocks came into line. Parliament finally made Greenwich Mean Time the legal time throughout Great Britain in 1880.

D In North America, the problem was far greater. The continent was so wide that a single national time was impossible, and before the 1880s the railroads operated on dozens of different times, often each company's own. On 18 November 1883, the railroads of the United States and Canada introduced a system of standard time zones, each covering a broad band of territory and differing from its neighbours by exactly one hour. In many places, the change took effect at midday, and the occasion became known as 'the day of two noons', because in towns that had to turn their clocks back, noon arrived twice. Remarkably, the new zones had no legal basis in the United States until 1918; for more than three decades, they were simply an agreement among private companies.

E Meanwhile, astronomers and geographers were debating a related question: from which line of longitude should the world measure east and west? Different nations used their own capitals or observatories as the starting point on their maps and charts, which caused confusion for navigators. In 1884, delegates from more than twenty countries met at a conference in Washington, D.C., and voted to adopt the meridian passing through Greenwich, in London, as the world's prime meridian. One reason for the choice was practical: a large majority of the world's shipping already used charts based on Greenwich. Not every country accepted the decision at once, however; France, for example, continued to use the Paris meridian for many years afterwards.

F The conference did not establish a worldwide system of time zones, but it prepared the ground for one. Over the following decades, country after country adopted a standard time defined in relation to Greenwich, most commonly a whole number of hours ahead of it or behind it, although a few chose offsets that include an extra half hour or even three-quarters of an hour. In practice, zone boundaries rarely follow lines of longitude exactly; they bend around national and regional borders, and some large countries have chosen to use a single time across their entire territory.

G Today, the precise time is no longer set by the sun, or even by an observatory at Greenwich. Since the 1960s, the second has been defined by the vibrations of atoms, and the world's official time scale, Coordinated Universal Time, is maintained by combining the readings of hundreds of atomic clocks in laboratories around the world. Yet the basic idea remains the one that the railways made necessary: people in widely separated places agreeing to read the same hour from their clocks. It is easy to forget how recent that agreement is, and how much argument it took to reach it.

The prime meridian and world time

In the nineteenth century, navigators were confused because different nations used their own capitals or (22) ______ as the starting point for measuring longitude. At a conference in 1884, delegates chose the meridian through Greenwich, partly because most of the world's (23) ______ already relied on charts based on it. The conference did not create a global system of (24) ______, but in the following decades most countries adopted a standard time linked to Greenwich. Zone boundaries seldom follow lines of longitude precisely, because they are adjusted to fit (25) ______. Today, the official world time scale is kept by combining data from hundreds of (26) ______.