True / False / Not Given

Reading Passage 1 – The Humble Pencil

A Few objects are as ordinary, or as overlooked, as the pencil. Billions are produced every year, and most of us have used one since early childhood without giving it a moment's thought. Yet the pencil has a surprisingly long and complicated history, shaped by geology, warfare, chemistry and commerce.

B The story usually begins in the sixteenth century in Borrowdale, a valley in the north-west of England, where an unusually pure deposit of graphite was discovered. Local shepherds are said to have used lumps of it to mark their sheep. At the time, nobody understood what the substance was. Because it left a dark grey mark rather like lead, it was called 'plumbago', from the Latin word for lead, and the misunderstanding has survived in the language ever since: we still talk about pencil 'lead', even though pencils have never contained the metal.

C Borrowdale graphite was so pure that it could be sawn into thin sticks and used directly for writing. These sticks were brittle and left marks on the hand, so users began wrapping them in string or sheepskin, and later inserting them into hollowed-out wooden holders. The graphite also had a more valuable use: it was used to line the moulds in which cannonballs were cast, producing smoother, rounder shot. The mine became so important that the English Crown took control of it, and at times it was flooded or guarded to prevent theft. Smuggling was common nonetheless.

D Elsewhere in Europe, pencil makers had to make do with impure graphite, which they ground into powder and mixed with substances such as sulphur or glue. The results were often scratchy and unreliable. The decisive breakthrough came in France in the 1790s. At war with Britain, France was cut off from English graphite, and the government asked the engineer and inventor Nicolas-Jacques Conté to find an alternative. His solution was to mix powdered graphite with clay, shape the mixture into rods and fire them in a kiln. The method had a further advantage that would prove enormously important: by changing the proportion of clay, the maker could control how hard or soft the pencil was. More clay produced a harder pencil and a lighter line; more graphite produced a softer pencil and a darker one.

E Conté's process is still the basis of pencil making today, and the grading systems used around the world grew out of it. In much of Europe, pencils are marked with letters: H for hard, B for black (that is, soft), and F, which is said to stand for 'fine point', for a grade between the two. Numbers alongside the letters indicate the degree, so a 4H is harder than a 2H, and a 6B softer than a 2B. In the United States, a simpler system of numbers is widely used, in which a 'number 2' pencil is roughly equivalent to the European HB.

F The wooden casing has a history of its own. For much of the nineteenth century, the preferred wood was red cedar from North America, which was soft, straight-grained and easy to sharpen. Demand was so great that by the early twentieth century supplies were running low, and manufacturers are reported to have bought up old cedar fences and barns simply to obtain the wood. Eventually most of them switched to incense cedar, which grows in the western United States and is still widely used.

G The rubber eraser arrived separately. In 1770 the English engineer Edward Nairne is credited with noticing that a piece of natural rubber could rub out pencil marks; before that, people often used pieces of bread. Rubber at that stage tended to become sticky and smelly in warm weather, and it was only after the development of vulcanisation in the 1840s, a process which made rubber far more durable, that erasers became common. In 1858 an American, Hymen Lipman, received a patent for a pencil with an eraser attached to one end, a design that remains familiar in many countries, although in much of Europe pencils are still usually sold without one.

H In an age of screens, it might be expected that the pencil would be disappearing. In fact, it continues to be manufactured in enormous numbers. It needs no power, works in extreme temperatures, and its marks can be erased – qualities that have kept it in use among artists, engineers, carpenters and schoolchildren alike.

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.

Reading Passage 1 – Living Partnerships: The Hidden World of Lichens

A Walk through almost any landscape on Earth, from a city pavement to a windswept mountain summit, and you are likely to pass lichens without noticing them. They appear as grey-green crusts on rocks, leafy patches on tree bark or tiny branching tufts hanging from twigs. For centuries, naturalists classified them as a single kind of plant, and it was not until the second half of the nineteenth century that scientists began to understand that a lichen is not one organism at all, but a partnership.

B At the heart of every lichen is a fungus. Fungi cannot make their own food, and most obtain it by breaking down dead material or by living on other organisms. The lichen fungus has taken a different route: it houses a population of microscopic photosynthetic partners, either green algae or cyanobacteria, within its tissues. These partners use sunlight to produce sugars, a proportion of which pass to the fungus. In return, the fungus provides a sheltered structure that protects its partners from intense light and from drying out, and it absorbs water and minerals from rain, dust and the surface on which it grows. The body that results from this cooperation looks and behaves quite unlike either partner growing alone. Recent studies have suggested that some lichens also contain additional partners, such as yeasts, which makes the picture more complicated still.

C This arrangement allows lichens to survive in places where few other living things can. They are found on bare rock in hot deserts, on the frozen soils of Antarctica and on the exposed bark of trees in the tropics. The key to their resilience is an ability to tolerate almost complete drying out. When water is scarce, a lichen simply shuts down: its metabolism slows almost to a halt, and it can remain in this dormant state for long periods. As soon as it is moistened by rain, dew or even humid air, it resumes photosynthesis, sometimes within minutes. Experiments carried out on spacecraft have even shown that certain species can survive a period of exposure to the vacuum and radiation of space.

D The price of this toughness is extremely slow growth. Because lichens are active only when they are both wet and exposed to light, many crust-forming species expand by no more than a millimetre or two a year, and some grow far more slowly. Scientists have turned this characteristic into a practical tool. By measuring the diameter of the largest lichens on a surface such as a gravestone, a rock fall or ground left behind by a retreating glacier, and comparing it with lichens on surfaces of known age, researchers can estimate how long the surface has been exposed. The technique, known as lichenometry, has been used to date glacial deposits formed over the last few centuries, although its accuracy depends on careful calibration for each region, since growth rates vary with climate.

E Lichens are also remarkably sensitive to the quality of the air around them. Having no roots and no waxy outer layer of the kind that protects the leaves of many plants, they absorb much of what they need directly from rain and the atmosphere, and pollutants are taken in along with nutrients. Sulphur dioxide, released when coal and oil are burned, is particularly damaging to many species. In the industrial cities of nineteenth-century Europe, observers noticed that lichens were disappearing from trees and walls, and later studies linked this loss to polluted air. Today, surveys of which species are present in an area are widely used as an inexpensive way of monitoring air quality, and in several European cities some lichens have returned as levels of sulphur dioxide have fallen.

F People have found other uses for lichens too. In the Arctic, some species form a major part of the winter diet of reindeer and caribou, which dig through the snow to reach them. For centuries, lichens were also an important source of dyes: certain species were fermented to produce purple and red colours for wool, and the chemical indicator litmus, which turns red in acidic and blue in alkaline conditions, was originally obtained from lichens. In addition, lichens produce a wide range of chemical compounds, many of which are not known from any other group of organisms, and some of these are now being investigated for possible medical use.

G Despite their resilience, lichens face new pressures. Although many species have recovered from sulphur pollution, others are harmed by nitrogen compounds from traffic and intensive farming, which favour a small number of nitrogen-tolerant species at the expense of more sensitive ones. Because lichens grow so slowly, communities that are damaged may take decades to recover. Ecologists argue that these modest organisms deserve more attention, not only because of their value as indicators, but also because of the many roles they play in the ecosystems they inhabit, from beginning the slow process of turning rock into soil to providing food and nesting material for animals.