You should spend about 20 minutes on Questions 1-5, which are based on Reading Passage below.

WOOD CHOPPERS

Every day for the last few months, the forests of Portugal and southern Spain have echoed with the sound of chopping wood as gangs of cork strippers bring this year's harvest to a close. This corner of Western Europe provides 80 per cent of the world's cork, and the traditional methods used to strip it have barely changed. With a special axe called a machado, a cork stripper makes a series of neat vertical cuts in the trunk, taking care not to swing too deep and kill the tree. The two-inch-thick bark is then gently prised away, leaving the tree naked from the waist down, with its upper branches untouched. Slowly the bark grows back, and after nine years the whole process begins again. The harvested cork is used in everything from gasketing materials to shoe soles, but its primary role has always been keeping wine and air apart. It is wine producers who provide the cork farmers with the majority of their income.

In 1999, according to government figures, bottle stoppers accounted for 71 per cent of cork exports by value. And as the world's biggest producer, the Portuguese cork industry is vital to the country's economy, earning 740 million euro in foreign sales last year and employing an estimated 500,000 people. Since the first factories began punching corks 200 years ago, the cork and wine trades have gone hand in hand. But lately the relationship has been showing signs of strain, especially in the UK where supermarkets are losing patience with natural cork's occasional imperfections. They claim the level of cork-taint, caused by a rogue chemical compound known as TCA, is unacceptable, and are moving swiftly towards synthetic stoppers. And this could spell the end for the cork forests of Portugal.

The first reliable plastic cork was invented in 1992 by the American company Supremecorq, which now supplies over 400 wineries worldwide. Today, its patented 'thermoplastic stopper' is being chased by seven plastic look-a-likes in the race to plug the 15 billion wine bottles produced each year. So far, plastic manufacturers have an estimated 2 per cent of the total, but this is set to rise exponentially.

The only barrier, as they see it, is a vague, sentimental attachment among consumers towards natural cork. In the UK, having convinced the big buyers who control 75 per cent of the market, this is beginning to erode fast. Already a quarter of the wines sold by Tesco and Asda/Walmart are bottled under plastic, and their main rivals are not far behind.

Having spent the last 20 years studying the cork forests, wildlife biologist Dr Luis Palma is in no doubt about the threat to the environment if cork loses the battle against plastic, for Portugal's 720,000 hectares of cork forests - a third of the world's total - support a fragile, biodiverse ecosystem. The value of the forests will diminish and there will be irresistible economic pressure for them to be replaced,' he says. 'It is hard to see anything that could replace cork that would be environmentally sustainable given the poor soil and harsh climate.' And the forests also support other aspects of the local economy. 'On a small patch of cork land a farmer can raise a herd of goats, a few cows and some pigs to forage for acorns and graze beneath the trees,' explains Helena Freitas, President of Portugal's oldest conservation group, the Liga para a Proteccao da Natureza.

So are there any alternatives? A Portuguese government scheme to convert the land to cereals after the war to provide food for people and livestock was abandoned as a disaster when it was realised the soil was simply not strong enough to support this type of monoculture. At present, cork's most serious rival is eucalyptus, a fast-growing cash-crop for the paper industry whose total plantings have tripled since the seventies to just under 700,000 hectares. Eucalyptus acts like a sponge, choking off the water supply to other plants, leaving the ground between the trees barren. The Royal Society for the Protection of Birds is deeply concerned about the consequences for a variety of native species and migrating birds such as the Blackcap and Common Crane. And there's also the risk of serious soil erosion leading to possible desertification.

Back in the UK the debate over cork has grown increasingly bitter with some supermarkets claiming that up to one bottle in every 12 is corked, a figure vehemently denied by the cork industry. While millions of pounds are being spent on trying to stamp out TCA, the producers of plastic corks say they just want a share of the market and are not out to replace anyone. But that may not be the way it turns out.