IELTS Academic Reading Practice Test 431

The saffron crocus, Crocus sativus, is an autumn-flowering plant whose value lies not in its petals but in three thread-like stigmas that hang inside each flower. It grows from a bulb-like corm that lies dormant through the summer and then sends up narrow leaves and pale purple flowers in autumn. Everything about the crop is labour-intensive: the flowers must be picked by hand, and the stigmas separated and dried before they lose their quality.

No one knows exactly where the crocus was first cultivated. Its wild ancestors appear to have grown somewhere in the eastern Mediterranean or south-west Asia, and the cultivated plant, which cannot reproduce without human help, has been grown for so long that its origins are uncertain. Saffron was certainly prized in the Bronze Age. Frescoes from the palace at Knossos on Crete, painted around 1500 BC, show figures gathering crocus flowers, and the plant appears in Egyptian, Greek and Roman writing as a dye, a perfume and a medicine.

The English name has travelled a long way: it comes, through Old French and Latin, from an Arabic word. Arab farmers carried the corm westwards across North Africa into the Iberian peninsula, and by the medieval period it was being grown in Spain, where it has remained a crop ever since. From Spain it spread to Italy, to parts of France and eventually to England.

In medieval Europe saffron was worth far more than most spices, and its price made fraud profitable. The dried petals of safflower, a quite different plant that also yields a yellow colour, were sold as saffron, and merchants sometimes mixed genuine stigmas with dyed fibres or weighed them while still damp. Some cities responded by appointing inspectors. In Nuremberg, records from the fifteenth century describe examinations of saffron offered for sale, and sellers of adulterated material faced severe penalties. The high price meant that saffron was used sparingly as a dye for cloth.

Saffron reached England in the later Middle Ages, though precisely how is unclear. A persistent legend tells of a pilgrim who hid a single corm in the hollow of his staff and brought it home, but the story cannot be verified. By the sixteenth century the town of Chipping Walden in Essex had become so closely associated with the crop that it took the name Saffron Walden, and the surrounding fields were dug over for corms. It was used there in cooking, as a medicine and as a dye, and appears in recipes for cakes and buns that survive in Cornwall as well as Essex.

Cultivation is straightforward but demanding. The corms are planted in summer, in well-drained soil in a sunny position, and the field is then left undisturbed; after a few years the corms become crowded and are lifted, separated and replanted in fresh ground. Saffron does best in climates with hot, dry summers and cool autumns, and it will not tolerate ground that stays wet. The flowering period lasts only two or three weeks, and everything depends on the weather during that short window: heavy rain, strong wind or an early frost can destroy a crop's value within hours.

Harvesting begins before sunrise, while the flowers are still closed, because stigmas exposed to strong sunlight deteriorate. Pickers move quickly along the rows, filling baskets with whole flowers, which are then taken apart by hand. The three crimson stigmas are removed, together with a short piece of the yellow style to which they are attached, and spread thinly to dry. The figures explain the price: roughly 150,000 flowers are needed to produce a single kilogram of dried saffron, and both the picking and the separating are done by hand.

What buyers pay for is a set of chemical compounds. The colour comes from crocin, a pigment that dissolves readily in water and gives saffron its characteristic golden hue; this is why a few threads will colour a large pan of rice. The bitterness comes from picrocrocin, which breaks down during drying to produce safranal, the volatile compound responsible for the spice's distinctive aroma. Quality is judged by measuring the concentration of crocin, and the spice is graded accordingly, with the darkest stigmas commanding the highest prices. Safflower, the plant once used to adulterate saffron, is still grown for oil and for its own dye.

Today the great majority of the world's saffron is grown in Iran, mainly in the dry north-east around Khorasan. Afghanistan has expanded production since the early 2000s, partly as an alternative to opium poppies, and Spain still grows saffron in La Mancha, where the harvest is celebrated each year. Almost all of it comes from small farms, and the work is done by families who know that a single hectare may yield only a few kilograms of the finished spice.

In the kitchen, saffron is used in tiny quantities and is usually steeped in warm liquid first, so that the colour spreads evenly. It flavours Spanish paella, Italian risotto and French fish stews, and it colours the sweet buns baked in Sweden for St Lucia's Day and in Cornwall. In parts of the Middle East and India it flavours rice and both savoury and sweet dishes. Cooks learn quickly that generosity is a mistake: too much saffron makes a dish bitter and medicinal, and the spice is therefore added with anxious care.

A walk along a cliff path in spring reveals how varied birds' eggs can be. Guillemots crowd onto narrow ledges, each pair incubating a single egg that may be white, pale blue, greenish or densely scrawled with dark lines, and no two look alike. On moorland nearby, a curlew's eggs are mottled brown and olive, so close to the colour of the surrounding heather that a walker can pass within a metre without seeing them. Explaining this diversity has occupied naturalists since the nineteenth century, and although much is now known, some of the most basic questions remain open.

Eggshell is made mainly of calcium carbonate, a chalky substance laid down in a gland at the end of the female's oviduct during the hours before the egg is laid. Colour is added in the same process, by two pigments that are breakdown products of haem, the substance that makes blood red. Protoporphyrin produces shades of red, brown and black, while biliverdin produces blue and green. The two behave differently. Protoporphyrin is deposited in cells near the outer surface of the shell, so it forms spots, streaks and scrawls; biliverdin is mixed through the whole thickness of the shell, giving a colour that is even and much harder to remove.

The colours inside an egg have a different origin altogether. The yellow of a yolk comes from carotenoids, pigments that a female obtains from her food and passes into the egg, which is why hens given diets rich in these compounds lay more strongly coloured yolks. Wild birds obtain these pigments from berries and insects, and the intensity of a yolk therefore varies with what the female has been able to eat. Poultry breeders have exploited the effect for generations, feeding hens on marigold petals to deepen the colour. Shell pigments, by contrast, are manufactured by the bird herself, so the two colours are quite independent.

For birds that nest on the ground, the value of camouflage is obvious. The eggs of plovers, terns and waders are speckled with dark pigment, and the effect is strengthened by the behaviour of the sitting adult, which stays put until an intruder is almost upon it and then bursts away noisily. Species that nest in holes and cavities face no such pressure: an owl's or a woodpecker's eggs, hidden in darkness, are usually plain white. Comparisons across species support the point: white eggs are uncommon among birds that lay in open nests.

A second pressure comes from other birds. Some species, notably cuckoos, lay their eggs in other birds' nests. Hosts fight back: reed warblers and other small songbirds learn the appearance of their own eggs and eject any that differ in colour or pattern from the rest of the clutch. Hosts are not infallible, and sometimes eject their own eggs by mistake. In response, female cuckoos have diversified into separate lines, each specialising in the eggs of one host species, so that a cuckoo's egg often mimics the host's closely. The result is an evolutionary race in which the details of egg markings matter enormously.

Egg patterns also serve as labels. On a crowded ledge, a guillemot returning from the sea must find its own egg among hundreds, and experiments in which eggs have been moved or swapped suggest that each bird learns the appearance of its own. The markings are extraordinarily variable, and the variation within a colony is far greater than the variation between colonies. A system of individual signatures, in other words, has evolved where space is scarce.

Markings may also reveal a weakness. Studies of great tits, small songbirds common in European woods, have found that heavily spotted eggs tend to have thinner shells than lightly spotted ones, and one explanation is that females short of calcium use protoporphyrin to reinforce the thinnest parts of the shell. On this view heavy spotting signals a problem, since a thinner shell is more likely to break. One suggestion is that dark pigment helps an egg to stay warm in a cold climate, where the advantage of heat retention may outweigh the risk of breakage; the evidence for this is suggestive rather than decisive.

A more recent line of argument concerns the blue-green pigment. Biliverdin is an antioxidant, a substance that mops up damaging molecules in the body, and using it to colour an egg may cost the female something. On this view, a richly coloured blue-green egg is an honest signal of a female in good condition, and some studies have reported that females in better condition lay more strongly coloured eggs. The evidence, however, is not yet conclusive; the effects found so far are modest, and other studies have failed to find them at all.

How the pigments come to be arranged in such precise and repeatable patterns is still not fully understood. The shell gland contains pigment cells whose contents are released at particular moments as the egg rotates and the shell thickens, but why a thrush's egg should be evenly spotted and a guillemot's scrawled with lines is a question of timing and mechanics that is still being investigated. What is clear is that every pattern is produced without any contact between the egg and the outside world: the colours are laid down in darkness, inside the mother, before the egg is laid.

Few questions in education divide teachers as sharply as what should be done with their most able pupils. In England and in parts of the United States, schools commonly run programmes for the 'gifted and talented', selecting children by test or by teacher judgement and teaching them separately for part of the week. In Germany and several neighbouring countries, children are divided at about the age of ten between different kinds of secondary school. In Finland and Japan, by contrast, the ordinary classroom is expected to stretch everyone. The differences are real. Parents campaign for separate provision, and schools in many competitive cities are glad to provide it. The question of whether such programmes help, however, hides at least three others: whom do they help, by how much, and at what cost to everybody else?

The argument in favour of separate provision begins with an observation that few teachers would dispute: a pupil who has already mastered long division gains little from another week of it, and boredom of that kind can turn into indifference or disruption. Reviews of research on acceleration — allowing a pupil to skip a year, or to take a course several years early — have generally concluded that accelerated pupils learn more than comparable classmates who are not accelerated, and that the social damage so often predicted does not, on average, appear. What such reviews cannot settle is why. In most studies the accelerated pupils were also taught by teachers who were enthusiastic about the arrangement, and it is impossible to separate the effect of moving faster from the effect of being taught by someone who believed in it. Similar difficulties affect comparisons between schools that select their pupils.

The weakest link in most programmes is the business of deciding who belongs in them. A test taken at four or five is a modest predictor of achievement at fifteen, and children develop at very different rates: a fluent early reader may be unremarkable at eleven, while a quiet child who says little in class may turn out to be the most able of all. Performance on the tests themselves is influenced by coaching and by the resources of the family, and the children of graduates are heavily over-represented in every programme I have seen described. Being designated gifted tends to raise a pupil's expectations, whereas being left out may lower them, and teachers who know which children have been selected may treat them differently. Critics therefore maintain that such a programme measures the home a child comes from as much as the child.

The evidence about the programmes themselves is thinner than campaigners on either side usually admit. Enrichment sessions of an hour a week, in which selected pupils are withdrawn from ordinary lessons to work on a project, have rarely been shown to produce measurable gains in achievement. Larger effects appear when the curriculum itself is changed: when pupils move faster, tackle material of a different kind, or follow independent projects under the supervision of a teacher with genuine expertise in the subject. Too often, however, what looks like the effect of selection turns out to be the effect of resources, since the pupils chosen for a programme may simply be taught in smaller classes by better-qualified teachers. Trials that assign pupils at random to a programme are rare, because parents object to them, and few evaluations follow pupils for more than a year or two.

Fairness is the most serious objection to separate provision. A programme can draw staff, money and the attention of senior managers away from everybody else, and in competitive cities it can become a marketing device, attracting exactly the families whose support a school most wants. Yet the argument from equity cuts both ways. Able children from poor families are the least likely to be identified in the first place and the most likely to be bored in class, and a well-run programme may be the only route by which some of them ever meet genuinely demanding work. It is telling that many critics of selection at five are entirely comfortable with selection at sixteen, when examination results rather than a test of general ability decide who goes where. The principle they object to, in other words, is not selection as such but who does the selecting.

The conclusion I would draw is that the argument has been conducted in the wrong terms. The evidence supports giving highly able pupils harder work and allowing them to move faster through material they have already grasped; it does not support selecting children at four, labelling them for a decade, or assuming that a programme designed by adults is necessarily good for them. A defensible policy would identify pupils later and more than once, would stretch them mainly within their own schools, would train ordinary teachers to do so, and would not depend on parents who know how to work the system. Abolishing programmes altogether would take away something valuable from a minority who need it, but leaving them exactly as they are protects an advantage for the families that need it least. What matters most is whether the work is hard enough to require effort.