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IELTS Academic Reading Practice Test 152 With Answers

IELTS Academic Reading Practice Test 152 With Answers

IELTS-Academic-Reading-Practice-Test-152-With-Answer
IELTS-Academic-Reading-Practice-Test-152-With-Answer
Reading Passage 1

You should spend about 20 minutes on Questions 1-13, which are based on Passage 1 below.

Astronaut ice cream, anyone?

Breeze-drying is a technique that can help to provide food for astronauts. But it also has other applications nearer home.

A

Freeze-drying is like suspended animation for food: you can store a freeze-dried meal for years, and then, when you’re finally ready to eat it, you can completely revitalize it with a little hot water. Even after several years, the original foodstuff will be virtually unchanged.

The technique basically involves completely removing the water from some material, such as food while leaving the rest of the material virtually intact. The main reason for doing this is either to preserve the food or to reduce its weight. Removing the water from food keeps it from spoiling, because the microorganisms such as bacteria that cause spoiling cannot survive without it. Similarly, the enzymes which occur naturally in food cannot cause ripening without water, so removing water from food will also stop the ripening process.

B

Freeze-drying significantly reduces the total weight of the food because most food is largely made up of water; for example, many fruits are more than 80.00% water. Removing this makes the food much lighter and therefore makes transportation less difficult. The military and camping-supply companies freeze-dry foods to make them easier for an individual to carry and NASA has also freeze-dried foods for the cramped quarters on board spacecraft.

The process is also used to preserve other sorts of material, such as pharmaceuticals. Chemists can greatly extend pharmaceutical shelf life by freeze-drying the material and storing it in a container free of oxygen and water. Similarly, research scientists may use freeze-drying to preserve biological samples for long periods of time. Even valuable manuscripts that had been water damaged have been saved by using this process.

C

Freeze-drying is different from simple drying because it can remove almost all the water from materials, whereas simple drying techniques can only remove 90-95%. This means that the damage caused by bacteria and enzymes can virtually be stopped rather than just slowed down. In addition, the composition and structure of the material is not significantly changed, so materials can be revitalized without compromising the quality of the original.

D

This is possible because in freeze-drying, solid water – ice – is converted directly into water vapour, missing out the liquid phase entirely. This is called ‘sublimation’, the shift from a solid directly into a gas. Just like evaporation, sublimation occurs when a molecule gains enough energy to break free from the molecules around it. Water will sublime from a solid (ice) to a gas (vapour) when the molecules have enough energy to break free but the conditions aren’t right for a liquid to form. These conditions are determined by heat and atmospheric pressure. When the temperature is above freezing point, so that ice can thaw, but the atmospheric pressure is too low for a liquid to form (below 0.06 atmospheres (ATM)) then it becomes a gas.

E

This is the principle on which a freeze-drying machine is based. The material to be preserved is placed in a freeze-drying chamber which is connected to a freezing coil and refrigerator compressor. When the chamber is sealed the compressor lowers the temperature inside it. The material is frozen solid, which separates the water from everything around it on a molecular level, even though the water is still present.

Next, a vacuum pump forces air out of the chamber, lowering the atmospheric pressure below to 0.06 ATM. The heating units apply a small amount of heat to the shelves in the chamber, causing the ice to change phase. Since the pressure in the chamber is so low, the ice turns directly into water vapour, which leaves the freeze-drying chamber, and flows past the freezing coil. The water vapour condenses onto the freezing coil in the form of solid ice, in the same way that water condenses as frost on a cold day.

F

The process continues for many hours (even days) while the material gradually dries out. This time is necessary to avoid overheating, which might affect the structure of the material. Once it has dried sufficiently, it is sealed in a moisture-free package. As long as the package is secure, the material can sit on a shelf for years and years without degrading, until it is restored to its original form with a little hot water. If everything works correctly, the material will go through the entire process almost completely unscathed.

In fact, freeze-drying, as a general concept, is not new but has been around for centuries. The ancient Incas of Peru used mountain peaks along the Andes as natural food preservers. The extremely cold temperatures and low pressure at those high altitudes prevented food from spoiling in the same basic way as a modern freeze-drying machine and a freezer.

Questions 1-5

IELTS Academic Reading Practice Test 152 With Answers

Complete the notes below.

Choose NO MORE THAN THREE WORDS from the passage for each answer.

Write your answers in boxes 1-5 on your answer sheet.

Uses of freeze-drying:

  • food preservation
  • easy 1 ……………… of food items
  •  long-term storage of 2 ……………… and biological samples
  •  preservation of precious 3 ………………

Freeze-drying

• is based on process of 4 ……………… is more efficient than 5 ………………

Questions 6-9

IELTS Academic Reading Practice Test 152 With Answers

Label the diagram below.

Choose NO MORE THAN TWO WORDS from the passage for each answer.

Write your answers in boxes 6-9 on your answer sheet.

                                          A simplified freeze-drying machine

Questions 10-13

IELTS Academic Reading Practice Test 152 With Answers

Complete the summary below.

Choose NO MORE THAN THREE WORDS AND/OR A NUMBER from the passage for each answer.

Write your answers in boxes 10-13 on your answer sheet.

Freeze-drying prevents food from going bad by stopping the activity of microorganisms or 10 ……………… Its advantages are that the food tastes and feels the same as the original because both the 11 ……………… and structure are preserved. The process is carried out slowly to ensure that 12 ……………… does not take place. The people of one ancient mountain civilisation were able to use this method of food preservation because the conditions needed were present at 13 ……………… .

Reading Passage 2

You should spend about 20 minutes on Questions 14- 26, which are based on Passage 2  below.

Neanderthals and modern humans

A

The evolutionary processes that have made modern humans so different from other animals are hard to determine without an ability to examine human species that have not achieved similar things. However, in a scientific masterpiece, Svante Paabo and his colleagues from the Max Planck Institute for Evolutionary Anthropology, in Leipzig, have made such a comparison possible. In 2009, at a meeting of the American Association for the Advancement of Science, they made public an analysis of the genome [1] of Neanderthal man.

B

Homo neanderthalensis, to give its proper name, lived in Europe and parts of Asia from 400,000 years ago to 30,000 years ago. Towards the end of this period, it shared its range with interlopers in the form of Homo sapiens [2], who were spreading out from Africa. However, the two species did not settle down to a stable cohabitation. For reasons which are as yet unknown, the arrival of Homo sapiens in a region was always quickly followed by the disappearance of Neanderthals.

C

Before 2009, Dr Paabo and his team had conducted only a superficial comparison between the DNA of Neanderthals and modern humans.  Since then, they have performed a more thorough study and, in doing so, have shed a fascinating light on the intertwined history of the two species. That history turns out to be more intertwined than many had previously believed.

D

Dr Paabo and his colleagues compared their Neanderthal genome (painstakingly reconstructed from three bone samples collected from a cave in Croatia) with that of five living humans from various parts of Africa and Eurasia. Previous genetic analysis, which had only examined DNA passed from mother to child in cellular structures called mitochondria, had suggested no interbreeding between Neanderthals and modern humans.

The new, more extensive examination, which looks at DNA in the cell nucleus rather than in the mitochondria, shows this conclusion is wrong. By comparing the DNA in the cell nucleus of Africans (whose ancestors could not have crossbred with Neanderthals, since they did not overlap with them) and various Eurasians (whose ancestors could have crossbred with Neanderthals), Dr Paabo has shown that Eurasians are between one percent and four percent Neanderthal.

E

That is intriguing. It shows that even after several hundred thousand years of separation, the two species were inter-fertile. It is strange, though, that no Neanderthal mitochondrial DNA has turned up in modern humans, since the usual pattern of invasion in historical times was for the invaders’ males to mate with the invaded’s females. One piece of self-knowledge, then – at least for non-Africans – is that they have a dash of Neanderthal in them. But Dr Paabo’s work also illuminates the differences between the species. By comparing modem humans, Neanderthals, and chimpanzees, it is possible to distinguish genetic changes which are shared by several species of human in their evolution away from the great-ape lineage, from those which are unique to Homo sapiens.

F

More than 90 percent of the ‘human accelerated regions’ [3] that have been identified in modem people are found in Neanderthals too. However, the rest are not. Dr Paabo has identified 212 parts of the genome that seem to have undergone significant evolution since the species split. The state of genome science is still quite primitive, and it is often unclear what any given bit of DNA is actually doing. But an examination of the 20 largest regions of DNA that have evolved in this way shows that they include several genes which are associated with cognitive ability, and whose malfunction causes serious mental problems. These genes, therefore, look like good places to start the search for modern humanity’s essence.

G

The newly evolved regions of DNA also include a gene called RUNX2, which controls bone growth. That may account for differences in the shape of the skull and the rib cage between the two species. By contrast, an earlier phase of the study had already shown that Neanderthals and moderns share the same version of a gene called FOXP2, which is involved in the ability to speak, and which differs in chimpanzees. It is all, then, very promising – and a second coup in quick succession for Dr Paabo. Another of his teams has revealed the existence of a hitherto unsuspected species of human, using mitochondrial DNA found in a little-finger bone. If that species, too, could have its full genome read, humanity’s ability to know itself would be enhanced even further.

[1] an individual’s complete set of genes
[2] the scientific name for modem humans
[3] parts of the human brain which evolved very rapidly

Questions 14-18

IELTS Academic Reading Practice Test 152 With Answers

Look at the following characteristics (Questions 14-18) and the list of species below.

Match each feature with the correct species, A, B or C.

Write the correct letter, A, B or C in boxes 14-18 on your answer sheet.

NB. You may use any letter more than once.

14. Once lived in Europe and Asia.
15. Originated in Africa.
16. Did not survive long after the arrival of immigrants.
17. Interbred with another species.
18. Appears not to have passed on mitochondrial DNA to another species.

List of species

A. Homo neanderthalensis
B. Homo sapiens
C. both Homo neanderthalensis and Homo sapiens

Questions 19-23

IELTS Academic Reading Practice Test 152 With Answers

Reading Passage 2  has seven paragraphs, A-G.

Which paragraph contains the following information?

Write the correct letter, A-G, in boxes 13-23 on your answer sheet.

19. an account of the rejection of a theory
20. reference to an unexplained link between two events
21. the identification of a skill-related gene common to both Neanderthals and modern humans
22. the announcement of a scientific breakthrough
23. an interesting gap in existing knowledge

Questions 24-26

IELTS Academic Reading Practice Test 152 With Answers

Complete the summary below.

Choose NO MORE THAN THREE WORDS from the passage for each answer.


The nature of modern humans

Recent work in the field of evolutionary anthropology has made it possible to compare modern humans with other related species. Genetic analysis resulted in several new findings.

First, despite the length of time for which Homo sapiens and Homo neanderthalensis had developed separately, 24 ………………  did take place.

Secondly, genes which evolved after modern humans split from Neanderthals are connected with cognitive ability and skeletal 25 ……………… .

The potential for this line of research to shed light on the nature of modern humans was further strengthened when analysis of a 26 ……………… led to the discovery of a new human species.

Reading Passage 3

You should spend about 20 minutes on Questions 27- 40, which are based on Passage 3 below.

Running on empty

A revolutionary new theory in sports physiology.

A

For almost a century, scientists have presumed, not unreasonably, that fatigue – or exhaustion in athletes originates in the muscles. Precise explanations have varied but all have been based on the ‘limitations theory’. In other words, muscles tire because they hit a physical limit: they either run out of fuel or oxygen or they drown in toxic by-products.

B

In the past few years, however, Timothy Noakes and Alan St Clair Gibson from the University of Cape Town, South Africa, have examined this standard theory. The deeper they dig, the more convinced they have become that physical fatigue simply isn’t the same as a car running out of petrol. Fatigue, they argue, is caused not by distress signals springing from overtaxed muscles, but is an emotional response which begins in the brain. The essence of their new theory is that the brain, using a mix of physiological, subconscious and conscious cues, paces the muscles to keep them well back from the brink of exhaustion. When the brain decides it’s time to quit, it creates the distressing sensations we interpret as unbearable muscle fatigue. This ‘central governor* theory remains controversial, but it does explain many puzzling aspects of athletic performance.

C

A recent discovery that Noakes calls the ‘lactic acid paradox’ made him seriously consider this area. Lactic acid is a by-product of exercise, and its accumulation is often cited as a cause of fatigue. But when research subjects exercise in conditions simulating high altitude, they become fatigued even though lactic acid levels remain low. Nor has the oxygen content of their blood fallen too low for them to keep going. Obviously, Noakes deduced, something else was making them tire before they hit either of these physiological limits.

D

Probing further, Noakes experimented with seven cyclists who had sensors taped to their legs to measure the nerve impulses travelling through their muscles. It has long been known that the body never uses 100% of the available muscle fibres in a single contraction during exercise. The amount used varies, but in endurance tasks such as this cycling test the body calls on about 30%.

E

Noakes reasoned that if the limitations theory was correct and fatigue was due to muscle fibres hitting some limit, the number of fibres used for each pedal stroke should increase as the fibres tired and the cyclist’s body attempted to compensate by recruiting an ever-larger proportion of the total. But his team found exactly the opposite. As fatigue set in, the cyclists’ legs’ electrical activity declined – even during sprinting, when they were striving to cycle as fast as they could.

F

To Noakes, this was strong evidence that the old theory was wrong. ‘The cyclists may have felt completely exhausted,’ he says, ‘but their bodies actually had considerable reserves that they could theoretically tap by using a greater proportion of the resting fibres.’ This, he believes, is proof that the brain is regulating the pace of the workout to hold the cyclists well back from the point of catastrophic exhaustion.

G  

More evidence comes from the fact that fatigued muscles don’t actually run out of anything critical. Levels of glycogen, which is the muscles’ primary fuel, and ATP. the chemical they use for temporary energy storage, decline with exercise but never bottom out. Even at the end of a marathon, ATP levels are 80-90% of the resting norm, and glycogen levels never get to zero.

H  

Further support for the central regulator comes from the fact that top athletes usually manage to go their fastest at the end of a race, even though, theoretically, that’s when their muscles should be closest to exhaustion. But Noakes believes the end spurt makes no sense if fatigue is caused by muscles poisoning themselves with lactic acid as this would cause racers to slow down rather than enable them to sprint for the finish line. In the new theory, the explanation is obvious. Knowing the end is near, the brain slightly relaxes its vigil, allowing the athlete to tap some of the body’s carefully hoarded reserves.

I

But the central governor theory does not mean that what’s happening in the muscles is irrelevant. The governor constantly monitors physiological signals from the muscles, along with other information, to set the level of fatigue. A large number of signals are probably involved but, unlike the limitations theory, the central governor theory suggests that these physiological factors are not the direct determinants of fatigue, but simply information to take into account.

J  

Conscious factors can also intervene. Noakes believes that the central regulator evaluates the planned workout, and sets a pacing strategy accordingly. Experienced runners know that if they set out on a 10-kilometre run. the first kilometre feels easier than the first kilometre of a 5-kilometre run, even though there should be no difference. That, Noakes says, is because the central governor knows you have further to go in the longer run and has programmed itself to dole out fatigue symptoms accordingly.

K

St Clair Gibson believes there is a good reason why our bodies are designed to keep something back. That way, there’s always something left in the tank for an emergency. In ancient times, and still today, life would be too dangerous if our bodies allowed us to become so tired that we couldn’t move quickly when faced with an unexpected need.

Questions 28-33

IELTS Academic Reading Practice Test 152 With Answers

Reading Passage 3 has eleven paragraphs A-K.

Choose the correct heading for Paragraphs A-F from the list of headings below.

Write the correct number (i-viii) in boxes 28-33 on your answer sheet.

List of headings

i       Avoiding tiredness in athletes
ii      Puzzling evidence raises a question
iii     Traditional explanations
iv     Interpreting the findings
v      Developing muscle fibres
vi     A new hypothesis
vii    Description of a new test
viii   Surprising results in an endurance test

28. Paragraph A
29. Paragraph B
30. Paragraph C
31. Paragraph D
32. Paragraph E
33. Paragraph F
Questions 34-40

IELTS Academic Reading Practice Test 152 With Answers

Classify the following ideas as relating to

A. the Limitations Theory
B. the Central Governor Theory
C. both the Limitations Theory and the Central Governor Theory

Write the correct letter A, B or C in boxes 34-40 on your answer sheet.

NB: You may use any letter more than once.

34. Lactic acid is produced in muscles during exercise.
35. Athletes can keep going until they use up all their available resources.
36. Mental processes control the symptoms of tiredness.
37. The physiological signals from an athlete’s muscles are linked to fatigue.
38. The brain plans and regulates muscle performance in advance of a run.
39. Athletes’ performance during a race may be affected by lactic acid build-up.
40. Humans are genetically programmed to keep some energy reserves.

Answer Key
Academic Reading Practice Test 151

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