IELTS CAM Inspired 16 - Reading Test 3 with Practice Test, Answers And Explanation
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IELTS Mock Test 16 - Reading Test 3 With Practice Test, Answers And Explanation
Passage
❓ Câu hỏi passage 1
Question 1 - 5
Do the following statements agree with the information given in the Reading Passage?
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
The Romans learned how to build ships from the peoples they had defeated.
2
The wrecks of ships have told historians more about Roman shipbuilding methods than surviving texts have.
3
Building the frame before the hull made ships faster to construct.
4
Warships sank as soon as they were damaged in battle.
5
Of all the rowers on a trireme, those positioned lowest had the easiest working conditions.
Question 6 - 13
Complete the summary below.
Choose ONE WORD ONLY from the passage for each answer.
Warships and merchant ships
The hull of a warship was and drawn out to a great length, and because the ship carried no ballast or spare weight, it stayed light and quick. At the bow sat a metal ram, driven in to hole an enemy's vessel or to disable the that propelled it. The rowers on a trireme were arranged in tiers, and each held close to fifty of them; far from being slaves, as people often assume, these men were mostly citizens performing service.
A merchant vessel's broader hull was reinforced with two thicknesses of and a firm inner core for steadiness. For steering, two large oars were mounted at the , one on each side, worked by a small lever linked to a network of cables. As a laden ship came in, a team of towboats would take hold of it and haul it up to the . Because the Romans had no navigational aids of the sort we call , a sailor out of sight of land fixed his course by the pole star or the noon sun.
Passage
❓ Câu hỏi passage 2
Question 14 - 19
Which section contains the following information?
Write the correct letter, A-H.
14
why hunting gear was abandoned in the high country
15
mention of how physically demanding the survey work was
16
a reason that food supplies might have fallen short
17
the suggestion that more finds may still come to light
18
instances of goods that were bought and sold
19
mention of the need for researchers to act without delay
Question 20 - 22
Complete the summary below.
Choose ONE WORD ONLY from the passage for each answer.
Interesting finds at an archaeological site
Remains made of organic matter — hides, textiles and similar materials — come to light only occasionally when sites are dug. With almost nothing to protect them from , such remains break down before long. Even so, this need not happen: given sufficiently low temperatures, fragile objects may last for thousands of years.
In the uplands of Sørdalen in Norway, researchers have been recovering items uncovered as the ice draws back. Long ago these passes carried the who tied far-flung communities together, and each summer reindeer moved up onto the frozen patches to get away from the that plagued the lower slopes. Whatever was left behind by the people who crossed here is exactly what now interests the archaeologists.
Question 23 - 24
Choose TWO letters, A-E.
Which TWO of the following points does the writer make about what Halvorsen's team found?
A
Hunters kept venturing into the mountains even in bitterly cold periods
B
Every object recovered from the high passes was a piece of skiing equipment
C
The team's radiocarbon dates proved unreliable
D
Sørdalen produced more finds than any other mountain location
E
Some periods were represented by only a scattering of objects
Question 25 - 26
Choose TWO letters, A-E.
According to the writer, which TWO of the following are true of the Viking Age?
A
The Vikings grew wealthier at the start of the period than at any other time
B
The growing appetite for goods worked to the hunters' advantage
C
Traders from across the world were drawn to Norway's expanding towns
D
Goods were carried overland as well as by sea
E
The Vikings were mainly concerned with their Middle Eastern trade links
Passage
❓ Câu hỏi passage 3
Question 27 - 32
Do the following statements agree with the information given in the Reading Passage?
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
Scientists already understood that phytochromes could detect warmth before this research was done.
28
Growing crops in warmer regions has become more expensive for farmers.
29
Maize and barley are among the crops that are harmed when temperatures rise.
30
When a plant is shaded, it puts on growth more quickly in an effort to reach sunlight.
31
Plants grow more quickly in cold conditions than in warm ones.
32
For a plant, its response to light matters more than its response to warmth.
Question 33 - 37
Which section contains the following information?
Write the correct letter, A-H.
33
the name of the journal in which the findings were published
34
a mention of the type of plant used in the experiments
35
an example of a named plant that blooms well before its usual time
36
a mention of how quickly phytochromes react to light
37
a suggestion about when plants' ability to sense temperature evolved
Question 38 - 40
Complete the sentences below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
38
In a
winter, crocuses may open their flowers well ahead of their normal time.
39
The tree that uses day length rather than temperature to time its growth is the
.
40
The team based their experiments on just one kind of
.
DOL IELTS Đình Lực
21/10/2026
📖 Bài đọc passage 1
Roman shipbuilding and navigation
Where a modern ship is built by science, worked out with computers and precision instruments, a vessel in ancient Rome was closer to a craft, guided by guesswork, handed-down methods and personal experience. Seafaring did not come naturally to the Romans, a largely land-dwelling people; the shipwright's skills reached them from the nations they had defeated in battle, above all the Greeks and the Egyptians.
Only a handful of written records survive picturing Rome's ships, their sails and rigging included, while the wrecks archaeologists have dug up offer further hints about how such craft were made. These sources tell us that a Roman shipwright would finish the outer shell of the hull before turning to the frame and the rest. At first the planks of that shell were stitched together; from the 6th century BCE, though, they were joined by the mortise-and-tenon technique, in which each plank slotted into the next with no stitching required. The opening centuries of our own era then saw Mediterranean shipbuilders take up a different approach, one still used now, in which the frame went up first and the hull followed. Being more methodical, it cut the time a ship took to build quite sharply. Vessels of the size and sophistication Rome achieved with its great cargo ships and warships would not be matched anywhere until the 16th century CE.
A warship was made to be light and swift. Because it needed to work the waters close inshore, it carried neither ballast nor any surplus load, and its hull was built long and narrow. Damage rarely sent such a ship to the bottom; after a sea battle the disabled hulls would frequently be left floating on the surface. Mounted on the vessel was a ram of bronze, driven into the wooden hulls of the enemy to hole them or to snap their oars. Drawing on the wind through its sails as well as the muscle of its oarsmen, a warship could move at great speed. In time the Roman fleet grew into the mightiest in the Mediterranean, a dominance that led the Romans to speak of the sea as Mare Nostrum, 'our sea'.
Warships came in many forms. From the 7th to the 4th century BCE the leading one was the 'trireme', whose oarsmen sat at three heights, upper, middle and lower, with something like fifty men to a bank. Those placed lowest fared worst: penned beneath their fellow rowers, they took the water that came in through the oar-holes. It is worth remembering, too, that these men were not, as is commonly imagined, slaves; most were Roman citizens serving in the military. Larger craft carrying still more rowers eventually replaced the trireme.
Cargo ships, by contrast, were designed to carry a great deal of freight a long way at reasonable cost. Their hulls were broader, sheathed in a double layer of planking, and given a solid core so they sat steadily. Where a warship stayed shallow, the deep V-shaped underside of a merchantman kept it well below the surface and stopped it hugging the coast. A pair of large steering-oars was fitted on either side off the stern, each worked by a slender tiller bar running to a set of cables. From one to three masts carried big square sails, with a small triangular one at the bow. Merchant ships were rowed too, and keeping hundreds of oarsmen in step was no simple matter; to help them, an instrument would sound and the oars kept time to the music.
What these ships carried ranged from raw materials, bars of iron, copper, and blocks of marble and granite, to farm produce such as the grain grown in the Nile valley of Egypt. Rome under the Empire was, by ancient standards, an enormous city of roughly a million people, and goods from every quarter reached it through two harbours: Pozzuoli, west of the Bay of Naples, and the vast complex at Ostia, where the Tiber meets the sea. On nearing its destination a large merchant ship would be met, much as one is today, by a group of towboats that hauled it in to the quay.
How long a voyage took varied greatly from route to route. Roman navigation leaned not on refined instruments such as compasses but on experience, familiarity with a stretch of water, and close observation of nature. When the air was clear, Mediterranean sailors could usually keep the mainland or an island in view, which made finding their way far easier, and they steered by their position against one familiar landmark after another. If the weather closed in, or the land dropped from sight, they judged their heading from the pole star or, less reliably, from the midday Sun, reading direction, too, from the wind and swell. On the whole, sea travel in Roman days was not unlike our own, with sizeable ships crossing the water again and again to carry supplies from across the Empire.
Climate change reveals ancient artefacts in Norway's glaciers
A
A. High above the treeline, in the loftiest parts of the Norwegian mountains, the ancient ice sheets are dwindling as the planet grows warmer. What that retreating ice surrenders as it melts are objects it has kept in frozen storage for as much as five thousand years — the arrows, skis and other gear once carried by hunters and by Viking-Age* merchants. For archaeologists, each of these finds has opened an unexpected window onto the ways in which the early inhabitants of Norway earned their living.
B
B. Cloth, hide and other organic remains are seldom recovered from archaeological sites, and the reason is simple: with little to shield them from the bacteria that drive decay, such materials rarely endure for long. Severe cold is one dependable exception, capable of holding an object more or less intact across several thousand years — though the moment it thaws, decay sets in quickly.
C
That is why the shrinking of the world's ice has turned glacial archaeology into a race. A delicate item, once it dries out and the wind gets at it, can disappear from the scientific record almost at once; an arrow, by contrast, may surface briefly and then be buried and protected again by the following winter's snow. Because there is no telling which will happen, those working on the ice have to approach each season methodically.
D
For eleven years, a team led by Ingrid Solberg of the Sørdalen County Heritage Office and Marcus Halvorsen of the Nordic Institute for Glacial Archaeology surveyed the ice of Sørdalen, a highland district in central Norway ringed by some of the nation's tallest peaks. Trade routes had long wound through its passes, carrying the traders who connected Norwegian settlements with the rest of Europe; and each summer, herds of reindeer would climb onto the ice to escape the biting flies that swarmed the valleys below, with hunters following close behind them from late in the Stone Age** onwards. Because a moving glacier grinds away whatever lies beneath it, the team concentrated on ice that stays put, most of it above 1,500 metres, set among frost-shattered boulders and bare rock that spend nine months of every year under snow. 'The work is punishing — long hikes under the weight of all your kit, nights camped on permafrost — and yet there is nothing like it,' Halvorsen says. 'You are saving the archaeology, drawing attention to the melting ice, piecing together an environmental story found nowhere else, and all the while in the closest possible contact with the natural world.'
E
Along the retreating margins of the ice, the archaeologists gathered upwards of 2,500 objects, together spanning an enormous stretch of time — from about 3,500 BCE right up to the dawn of the Renaissance in the fifteenth century. A great many of them have to do with hunting. An arrow was an easy thing to mislay, and a bow, once broken, was more often abandoned on the spot than carried the long way home. Other finds are things any traveller crossing the high passes might have used: everyday tools, skis, and pieces of horse tack.
F
Halvorsen's team obtained radiocarbon dates for 178 of the objects and lined those dates up against the region's major turning points — spells of warming and cooling on the one hand, and on the other the social and economic changes of the era, such as the spread of farming and the widening of international trade in the run-up to the Viking Age. Certain stretches of time had left behind a wealth of objects, a sign that people had been busy in the mountains then; from other stretches there was little or nothing. The distribution of these periods was, to Halvorsen, the real surprise. Sørdalen's heights are forbidding, and in the coldest spells glaciers could seal off the upper passes and make travel there all but impossible, so one might expect people to have kept to lower ground during an episode like the sixth-century cold snap of roughly 540 to 600 CE. Instead, judging by how much they had left behind on the ice, hunters went on climbing into the mountains as often as ever. 'What is striking is that the finds seem to carry on right through that cold phase,' he says, 'which may mean that hunting in the mountains mattered more, not less, when harvests were failing in the cold.' A downturn in the Scandinavian climate would have ruined crops across the region, and the loss would have pushed more people to rely on what they could hunt.
G
A large share of the objects belong to the early Viking Age, the eighth to the tenth centuries CE, just as the trade networks binding Scandinavia to Europe and the Middle East were growing. Scandinavian expansion tends to bring ships to mind, yet these finds are a reminder that a great deal also moved overland, along corridors like the Sørdalen passes. The expanding towns of Norway, and the markets abroad, would have generated brisk demand — for hides to keep out the cold, and for antlers from which to fashion useful objects such as combs. For a hunter, in other words, the times were good.
H
Norway's mountains almost certainly hold a great deal more history — and prehistory — in their remote pockets of ice. Looking again at the dates for their 178 objects, the researchers noticed an almost complete blank between roughly 3,600 and 2,000 BCE; and indeed, finds from those centuries are scarce right across Norway. It may be, they suggest, that the objects have long since crumbled away, or else that they are lying still frozen and out of reach. If so, the retreating ice of the years ahead could yet give them up.
I
* Viking Age: a period of European history from around 700 CE to around 1050 CE when Scandinavian Vikings migrated throughout Europe by means of trade and warfare ** The Stone Age: a period in early history that began about 3.4 million years ago
Plant 'thermometer' triggers springtime growth by measuring night-time heat
A pigment that plant cells use to sense light turns out to have a second job after dark: as a thermometer, it lets plants follow the seasons' shifting temperatures. Its discoverers believe it could open the way to crops better suited to the warmer world that climate change will bring.
A
A. Working across several countries under the lead of the Ravensworth Plant Science Institute, researchers have shown that a 'thermometer' molecule lets plants time their development to the seasons' changing warmth. These molecules, called phytochromes, are the very ones plants use to register daylight; after dark, the study reveals, they switch roles entirely, becoming cellular gauges that read how warm the night has grown. Set out in the journal Botanical Advances, the findings show phytochromes throw genetic switches in answer to temperature, not to light alone, so steering a plant's growth.
B
B. Once the sun is down the molecules shift from one state to another, and the speed of that shift mirrors the temperature exactly — a phytochrome, the researchers suggest, behaves like the mercury in a thermometer. Warmer conditions drive the change faster, spurring growth.
C
Growers have appreciated for centuries just how sensitive plants are to warmth: a mild winter tips many trees and flowers into early bud, a signal people have long read to anticipate the weather and reckon when the year's crops would be ready. Where this study breaks new ground is in identifying, for the very first time, the molecular apparatus within the plant that answers to temperature — the same machinery that brings on those first buds of spring so eagerly awaited once winter recedes.
D
As climate change makes temperature and weather ever less predictable, the researchers argue that learning this light-sensor doubles as the plant's own internal thermometer could help us raise hardier crops. 'By the middle of the century, the world will need to grow far more food, and a warming climate is the principal obstacle to that,' says Professor Skovgaard, who directed the work at Ravensworth. 'Staples such as maize and barley struggle in the heat — for each degree the temperature rises, something like eight percent of the harvest is lost. Working out which molecules let a plant register warmth could therefore hasten the breeding of varieties that hold up under heat and a shifting climate.'
E
While switched on, phytochrome molecules fix themselves to DNA and hold a plant's growth in check. Sunlight is what switches them on, so growth eases off by day. Let a plant fall into shade, though, and its phytochromes switch off almost at once, freeing it to grow faster and climb back toward the light — this is how neighbouring plants jostle out of one another's shadow. 'The light-driven switch in a phytochrome's activity is remarkably rapid, over in under a second,' says Skovgaard. Night is another matter. Rather than shutting off sharply at sunset, the molecules ease gradually from active to inactive, a shift termed 'dark reversion'. 'Much as mercury creeps up a thermometer, the rate at which phytochromes fall back to their inactive form through the night gives a direct reading of temperature,' she says.
F
'The colder it is, the more slowly the phytochromes revert, so they dwell longer in the active form that suppresses growth — and that is why plants creep along in winter. Warmth speeds dark reversion up, so the phytochromes reach their inactive form quickly and release the plant's DNA, letting genes switch on and growth start up once more.' In Skovgaard's view, this knack for sensing temperature arose later in evolutionary history, taking over the machinery already devoted to light-driven growth during the quiet hours of the night.
G
Certain plants read the season mainly from the length of the day. Others — crocuses are one — respond strongly to warmth, and in a mild winter they may flower weeks earlier than usual. The finding that phytochromes play this twofold role also puts science behind an old rural saying about a pair of trees: birch before rowan, the summer runs dry; rowan before birch, and the fields end up drowned. 'Birch depends heavily on temperature, most likely turning to phytochromes as its thermometer to guide its growth, whereas rowan reads the length of the day to settle the timing of its year,' Skovgaard explains. 'A warm spring, and with it a better chance of a hot summer, brings birch into leaf before rowan; a cold spring flips that around. And as country people know all too well, a cooler summer is apt to be a rainy one.'
H
Nine years of work lie behind these results, bringing together scientists from Japan, Sweden and Canada alongside the Ravensworth group. A model system was used for the experiments — a grass known as Brachypodium — though Skovgaard points out that the phytochrome genes needed to sense temperature are present in food crops as well. 'Thanks to recent progress in plant genetics, researchers can now quickly locate the genes that steer these processes in crop species, and even tune their activity with exact molecular "scalpels",' she adds. 'For this kind of work Ravensworth is unusually well placed, with first-rate collaborators nearby whose focus on the applied side of plant biology helps carry our findings into the field.'
Where a modern ship is built by science, worked out with computers and precision instruments, a vessel in ancient Rome was closer to a craft, guided by guesswork, handed-down methods and personal experience. Seafaring did not come naturally to the Romans, a largely land-dwelling people; the shipwright's skills reached them from the nations they had defeated in battle, above all the Greeks and the Egyptians.
Only a handful of written records survive picturing Rome's ships, their sails and rigging included, while the wrecks archaeologists have dug up offer further hints about how such craft were made. These sources tell us that a Roman shipwright would finish the outer shell of the hull before turning to the frame and the rest. At first the planks of that shell were stitched together; from the 6th century BCE, though, they were joined by the mortise-and-tenon technique, in which each plank slotted into the next with no stitching required. The opening centuries of our own era then saw Mediterranean shipbuilders take up a different approach, one still used now, in which the frame went up first and the hull followed. Being more methodical, it cut the time a ship took to build quite sharply. Vessels of the size and sophistication Rome achieved with its great cargo ships and warships would not be matched anywhere until the 16th century CE.
A warship was made to be light and swift. Because it needed to work the waters close inshore, it carried neither ballast nor any surplus load, and its hull was built long and narrow. Damage rarely sent such a ship to the bottom; after a sea battle the disabled hulls would frequently be left floating on the surface. Mounted on the vessel was a ram of bronze, driven into the wooden hulls of the enemy to hole them or to snap their oars. Drawing on the wind through its sails as well as the muscle of its oarsmen, a warship could move at great speed. In time the Roman fleet grew into the mightiest in the Mediterranean, a dominance that led the Romans to speak of the sea as Mare Nostrum, 'our sea'.
Warships came in many forms. From the 7th to the 4th century BCE the leading one was the 'trireme', whose oarsmen sat at three heights, upper, middle and lower, with something like fifty men to a bank. Those placed lowest fared worst: penned beneath their fellow rowers, they took the water that came in through the oar-holes. It is worth remembering, too, that these men were not, as is commonly imagined, slaves; most were Roman citizens serving in the military. Larger craft carrying still more rowers eventually replaced the trireme.
Cargo ships, by contrast, were designed to carry a great deal of freight a long way at reasonable cost. Their hulls were broader, sheathed in a double layer of planking, and given a solid core so they sat steadily. Where a warship stayed shallow, the deep V-shaped underside of a merchantman kept it well below the surface and stopped it hugging the coast. A pair of large steering-oars was fitted on either side off the stern, each worked by a slender tiller bar running to a set of cables. From one to three masts carried big square sails, with a small triangular one at the bow. Merchant ships were rowed too, and keeping hundreds of oarsmen in step was no simple matter; to help them, an instrument would sound and the oars kept time to the music.
What these ships carried ranged from raw materials, bars of iron, copper, and blocks of marble and granite, to farm produce such as the grain grown in the Nile valley of Egypt. Rome under the Empire was, by ancient standards, an enormous city of roughly a million people, and goods from every quarter reached it through two harbours: Pozzuoli, west of the Bay of Naples, and the vast complex at Ostia, where the Tiber meets the sea. On nearing its destination a large merchant ship would be met, much as one is today, by a group of towboats that hauled it in to the quay.
How long a voyage took varied greatly from route to route. Roman navigation leaned not on refined instruments such as compasses but on experience, familiarity with a stretch of water, and close observation of nature. When the air was clear, Mediterranean sailors could usually keep the mainland or an island in view, which made finding their way far easier, and they steered by their position against one familiar landmark after another. If the weather closed in, or the land dropped from sight, they judged their heading from the pole star or, less reliably, from the midday Sun, reading direction, too, from the wind and swell. On the whole, sea travel in Roman days was not unlike our own, with sizeable ships crossing the water again and again to carry supplies from across the Empire.
C. That is why the shrinking of the world's ice has turned glacial archaeology into a race. A delicate item, once it dries out and the wind gets at it, can disappear from the scientific record almost at once; an arrow, by contrast, may surface briefly and then be buried and protected again by the following winter's snow. Because there is no telling which will happen, those working on the ice have to approach each season methodically.
D. For eleven years, a team led by Ingrid Solberg of the Sørdalen County Heritage Office and Marcus Halvorsen of the Nordic Institute for Glacial Archaeology surveyed the ice of Sørdalen, a highland district in central Norway ringed by some of the nation's tallest peaks. Trade routes had long wound through its passes, carrying the traders who connected Norwegian settlements with the rest of Europe; and each summer, herds of reindeer would climb onto the ice to escape the biting flies that swarmed the valleys below, with hunters following close behind them from late in the Stone Age** onwards. Because a moving glacier grinds away whatever lies beneath it, the team concentrated on ice that stays put, most of it above 1,500 metres, set among frost-shattered boulders and bare rock that spend nine months of every year under snow. 'The work is punishing — long hikes under the weight of all your kit, nights camped on permafrost — and yet there is nothing like it,' Halvorsen says. 'You are saving the archaeology, drawing attention to the melting ice, piecing together an environmental story found nowhere else, and all the while in the closest possible contact with the natural world.'
E. Along the retreating margins of the ice, the archaeologists gathered upwards of 2,500 objects, together spanning an enormous stretch of time — from about 3,500 BCE right up to the dawn of the Renaissance in the fifteenth century. A great many of them have to do with hunting. An arrow was an easy thing to mislay, and a bow, once broken, was more often abandoned on the spot than carried the long way home. Other finds are things any traveller crossing the high passes might have used: everyday tools, skis, and pieces of horse tack.
F. Halvorsen's team obtained radiocarbon dates for 178 of the objects and lined those dates up against the region's major turning points — spells of warming and cooling on the one hand, and on the other the social and economic changes of the era, such as the spread of farming and the widening of international trade in the run-up to the Viking Age. Certain stretches of time had left behind a wealth of objects, a sign that people had been busy in the mountains then; from other stretches there was little or nothing. The distribution of these periods was, to Halvorsen, the real surprise. Sørdalen's heights are forbidding, and in the coldest spells glaciers could seal off the upper passes and make travel there all but impossible, so one might expect people to have kept to lower ground during an episode like the sixth-century cold snap of roughly 540 to 600 CE. Instead, judging by how much they had left behind on the ice, hunters went on climbing into the mountains as often as ever. 'What is striking is that the finds seem to carry on right through that cold phase,' he says, 'which may mean that hunting in the mountains mattered more, not less, when harvests were failing in the cold.' A downturn in the Scandinavian climate would have ruined crops across the region, and the loss would have pushed more people to rely on what they could hunt.
G. A large share of the objects belong to the early Viking Age, the eighth to the tenth centuries CE, just as the trade networks binding Scandinavia to Europe and the Middle East were growing. Scandinavian expansion tends to bring ships to mind, yet these finds are a reminder that a great deal also moved overland, along corridors like the Sørdalen passes. The expanding towns of Norway, and the markets abroad, would have generated brisk demand — for hides to keep out the cold, and for antlers from which to fashion useful objects such as combs. For a hunter, in other words, the times were good.
H. Norway's mountains almost certainly hold a great deal more history — and prehistory — in their remote pockets of ice. Looking again at the dates for their 178 objects, the researchers noticed an almost complete blank between roughly 3,600 and 2,000 BCE; and indeed, finds from those centuries are scarce right across Norway. It may be, they suggest, that the objects have long since crumbled away, or else that they are lying still frozen and out of reach. If so, the retreating ice of the years ahead could yet give them up.
I. * Viking Age: a period of European history from around 700 CE to around 1050 CE when Scandinavian Vikings migrated throughout Europe by means of trade and warfare ** The Stone Age: a period in early history that began about 3.4 million years ago
C. Growers have appreciated for centuries just how sensitive plants are to warmth: a mild winter tips many trees and flowers into early bud, a signal people have long read to anticipate the weather and reckon when the year's crops would be ready. Where this study breaks new ground is in identifying, for the very first time, the molecular apparatus within the plant that answers to temperature — the same machinery that brings on those first buds of spring so eagerly awaited once winter recedes.
D. As climate change makes temperature and weather ever less predictable, the researchers argue that learning this light-sensor doubles as the plant's own internal thermometer could help us raise hardier crops. 'By the middle of the century, the world will need to grow far more food, and a warming climate is the principal obstacle to that,' says Professor Skovgaard, who directed the work at Ravensworth. 'Staples such as maize and barley struggle in the heat — for each degree the temperature rises, something like eight percent of the harvest is lost. Working out which molecules let a plant register warmth could therefore hasten the breeding of varieties that hold up under heat and a shifting climate.'
E. While switched on, phytochrome molecules fix themselves to DNA and hold a plant's growth in check. Sunlight is what switches them on, so growth eases off by day. Let a plant fall into shade, though, and its phytochromes switch off almost at once, freeing it to grow faster and climb back toward the light — this is how neighbouring plants jostle out of one another's shadow. 'The light-driven switch in a phytochrome's activity is remarkably rapid, over in under a second,' says Skovgaard. Night is another matter. Rather than shutting off sharply at sunset, the molecules ease gradually from active to inactive, a shift termed 'dark reversion'. 'Much as mercury creeps up a thermometer, the rate at which phytochromes fall back to their inactive form through the night gives a direct reading of temperature,' she says.
F. 'The colder it is, the more slowly the phytochromes revert, so they dwell longer in the active form that suppresses growth — and that is why plants creep along in winter. Warmth speeds dark reversion up, so the phytochromes reach their inactive form quickly and release the plant's DNA, letting genes switch on and growth start up once more.' In Skovgaard's view, this knack for sensing temperature arose later in evolutionary history, taking over the machinery already devoted to light-driven growth during the quiet hours of the night.
G. Certain plants read the season mainly from the length of the day. Others — crocuses are one — respond strongly to warmth, and in a mild winter they may flower weeks earlier than usual. The finding that phytochromes play this twofold role also puts science behind an old rural saying about a pair of trees: birch before rowan, the summer runs dry; rowan before birch, and the fields end up drowned. 'Birch depends heavily on temperature, most likely turning to phytochromes as its thermometer to guide its growth, whereas rowan reads the length of the day to settle the timing of its year,' Skovgaard explains. 'A warm spring, and with it a better chance of a hot summer, brings birch into leaf before rowan; a cold spring flips that around. And as country people know all too well, a cooler summer is apt to be a rainy one.'
H. Nine years of work lie behind these results, bringing together scientists from Japan, Sweden and Canada alongside the Ravensworth group. A model system was used for the experiments — a grass known as Brachypodium — though Skovgaard points out that the phytochrome genes needed to sense temperature are present in food crops as well. 'Thanks to recent progress in plant genetics, researchers can now quickly locate the genes that steer these processes in crop species, and even tune their activity with exact molecular "scalpels",' she adds. 'For this kind of work Ravensworth is unusually well placed, with first-rate collaborators nearby whose focus on the applied side of plant biology helps carry our findings into the field.'
