Reading Comprehension

DNA degrades quickly after an animal dies, so researchers once believed it impossible to find ancient genetic material. The search for primeval vestiges of DNA took off in the late 1980s after the development of a technique called polymerase chain reaction (PCR), which copies minute quantities of DNA. Armed with PCR, scientists could look for tiny fragments of DNA that might have weathered the millennia unharmed.

In recent years, researchers have isolated DNA from 20-million-year-old magnolia leaves and extracted DNA from a 135-million-year-old weevil found in amber. Recently, a team extract DNA from bone dating back millions of years for the first time. In the frenzied hunt for ancient DNA, microbiologist Scott R. Woodward may have bagged the biggest quarry. Drawing on lessons learned while growing up among the fossil-rich rocks of eastern Utah, Woodward and his team became the first people to find genetic material belonging to a dinosaur.

Woodward, whose grandfather was a coal miner, knew that mines in the area often contained dinosaur traces. After six months of looking Woodward pulled two bone fragments from a Cretaceous siltstone layer directly atop a coal seam. Impeded by an unstable mine roof, Woodward's team could not recover any more bone samples. The siltstone apparently inhibited fossilization and preserved much of the original cell structure in the bone. Researchers isolated strands of DNA from both fragments and used PCR to copy a segment that codes for a protein called cytochrome b. Once they had made many copies, they could determine the DNA sequence.

Throughout their work, the biologists took precautions to avoid contaminating the samples with modern DNA or ancient material found within the coal. According to Woodward, circumstantial evidence indicates that the bone fragments belong to one or two species of dinosaurs. Dinosaur tracks are abundant in this coal formation, and the bones visible in the mine were larger than those of a crocodile—the biggest non-dinosaur known in these rocks.

Woodward explains variation found in the DNA as a result of damage to the ancient DNA, which caused the PCR technique to alter the original sequence. Scientists had hoped to use the DNA to resolve debate about the relationship among birds, dinosaurs, and other reptiles. But the cytochrome b fragments were too short to offer meaningful phylogenetic information, says Woodward. Utah's state paleontologist believes that the fragments found by Woodward could definitely be dinosaur in origin. Other researchers, however, question the identity of the DNA strands. Because the copies of the cytochrome b sequence varied considerably, they wonder whether the DNA comes from several organisms.

Based on the passage, Woodward was pointing on what circumstantial evidences?

The four sentences (labelled 1, 2, 3 and 4) below, when properly sequenced, would yield a coherent paragraph. Decide on the proper sequencing of the order of the sentences and choose the correct option.

1. What we really are comes to the fore only rarely and in some specific circumstances.
2. What we think of ourselves as is, often, what determines how we behave, and our behaviour, we believe, determines what others think of us.
3. However, what we really are is hidden from others, either because we deliberately hide it from others or because we are unaware of how we actually are.
4. Like when we are in a crisis or under tremendous pressure, or conversely, when we are in a position of power and authority

DNA degrades quickly after an animal dies, so researchers once believed it impossible to find ancient genetic material. The search for primeval vestiges of DNA took off in the late 1980s after the development of a technique called polymerase chain reaction (PCR), which copies minute quantities of DNA. Armed with PCR, scientists could look for tiny fragments of DNA that might have weathered the millennia unharmed.

In recent years, researchers have isolated DNA from 20-million-year-old magnolia leaves and extracted DNA from a 135-million-year-old weevil found in amber. Recently, a team extract DNA from bone dating back millions of years for the first time. In the frenzied hunt for ancient DNA, microbiologist Scott R. Woodward may have bagged the biggest quarry. Drawing on lessons learned while growing up among the fossil-rich rocks of eastern Utah, Woodward and his team became the first people to find genetic material belonging to a dinosaur.

Woodward, whose grandfather was a coal miner, knew that mines in the area often contained dinosaur traces. After six months of looking Woodward pulled two bone fragments from a Cretaceous siltstone layer directly atop a coal seam. Impeded by an unstable mine roof, Woodward's team could not recover any more bone samples. The siltstone apparently inhibited fossilization and preserved much of the original cell structure in the bone. Researchers isolated strands of DNA from both fragments and used PCR to copy a segment that codes for a protein called cytochrome b. Once they had made many copies, they could determine the DNA sequence.

Throughout their work, the biologists took precautions to avoid contaminating the samples with modern DNA or ancient material found within the coal. According to Woodward, circumstantial evidence indicates that the bone fragments belong to one or two species of dinosaurs. Dinosaur tracks are abundant in this coal formation, and the bones visible in the mine were larger than those of a crocodile—the biggest non-dinosaur known in these rocks.

Woodward explains variation found in the DNA as a result of damage to the ancient DNA, which caused the PCR technique to alter the original sequence. Scientists had hoped to use the DNA to resolve debate about the relationship among birds, dinosaurs, and other reptiles. But the cytochrome b fragments were too short to offer meaningful phylogenetic information, says Woodward. Utah's state paleontologist believes that the fragments found by Woodward could definitely be dinosaur in origin. Other researchers, however, question the identity of the DNA strands. Because the copies of the cytochrome b sequence varied considerably, they wonder whether the DNA comes from several organisms.

All of the following, IF TRUE, would strengthen the author's claims EXCEPT

Direction: The passage below is accompanied by a set of questions. Choose the best answer to each question.

DNA degrades quickly after an animal dies, so researchers once believed it impossible to find ancient genetic material. The search for primeval vestiges of DNA took off in the late 1980s after the development of a technique called polymerase chain reaction (PCR), which copies minute quantities of DNA. Armed with PCR, scientists could look for tiny fragments of DNA that might have weathered the millennia unharmed.

In recent years, researchers have isolated DNA from 20-million-year-old magnolia leaves and extracted DNA from a 135-million-year-old weevil found in amber. Recently, a team extract DNA from bone dating back millions of years for the first time. In the frenzied hunt for ancient DNA, microbiologist Scott R. Woodward may have bagged the biggest quarry. Drawing on lessons learned while growing up among the fossil-rich rocks of eastern Utah, Woodward and his team became the first people to find genetic material belonging to a dinosaur.

Woodward, whose grandfather was a coal miner, knew that mines in the area often contained dinosaur traces. After six months of looking Woodward pulled two bone fragments from a Cretaceous siltstone layer directly atop a coal seam. Impeded by an unstable mine roof, Woodward's team could not recover any more bone samples. The siltstone apparently inhibited fossilization and preserved much of the original cell structure in the bone. Researchers isolated strands of DNA from both fragments and used PCR to copy a segment that codes for a protein called cytochrome b. Once they had made many copies, they could determine the DNA sequence.

Throughout their work, the biologists took precautions to avoid contaminating the samples with modern DNA or ancient material found within the coal. According to Woodward, circumstantial evidence indicates that the bone fragments belong to one or two species of dinosaurs. Dinosaur tracks are abundant in this coal formation, and the bones visible in the mine were larger than those of a crocodile—the biggest non-dinosaur known in these rocks.

Woodward explains variation found in the DNA as a result of damage to the ancient DNA, which caused the PCR technique to alter the original sequence. Scientists had hoped to use the DNA to resolve debate about the relationship among birds, dinosaurs, and other reptiles. But the cytochrome b fragments were too short to offer meaningful phylogenetic information, says Woodward. Utah's state paleontologist believes that the fragments found by Woodward could definitely be dinosaur in origin. Other researchers, however, question the identity of the DNA strands. Because the copies of the cytochrome b sequence varied considerably, they wonder whether the DNA comes from several organisms.

According to the passage, which myth was surpassed by the researchers later in the 1980s?

The passage given below is followed by four alternate summaries. Choose the option that best captures the essence of the passage.

The past decade has seen a decline in the uptake of almost all routine vaccinations for children in England. Currently, no childhood vaccinations meet the 95% target set by the World Health Organization. The US has a similar shortfall, and the WHO warns that the long-term decline in childhood vaccination rates is a global phenomenon. Here, the consequences have been increased cases of vaccine-preventable diseases such as whooping cough in nurseries and schools, as well as a rising number of polio samples found in sewage in London.

The passage given below is followed by four alternate summaries. Choose the option that best captures the essence of the passage.

Before the 1800s, fashion was slow. You had to source your own materials like wool or leather, prepare them, weave them, and then make the clothes. The Industrial Revolution introduced new technology—like the sewing machine. Clothes became easier, quicker, and cheaper to make. Dressmaking shops emerged to cater to the middle classes. Many of these dressmaking shops used teams of garment workers or home workers. Around this time, sweatshops emerged, along with some familiar safety issues. The first significant garment factory disaster was when a fire broke out in New York's Triangle Shirtwaist Factory in 1911. It claimed the lives of 146 garment workers, many of whom were young female immigrants.

The rapid loss of frozen Arctic soil, known as permafrost, that contains more carbon dioxide than has ever been released by humans, is one of the most alarming causes of global warming that the world will face in coming years. Some scientific studies indicate that the Arctic is warming twice as fast as other parts of the planet and could lose all its ice by 2030.

While the Arctic may seem remote and thereby be given negligible consideration in its rising environmental concerns, the truth is that the overall rate of global warming – right from changing climates and rising sea levels to disruption of wildlife habitats and coastal villages – is affected by the heating of the Arctic.

Studies from Woods Hole Research Center (“WHRC”) attribute the cause of this environmental disaster to the fate of the permafrost underlying the Arctic. Permafrost, part of the Earth's bedrock that is most vulnerable to warming, forms in climates where the mean air temperate is lower than the freezing point of water.

Permafrost comprises 25 per cent of the land in the Northern Hemisphere. It consists of rock, soil, sediments and ice that binds all the components together. While permafrost is defined as ground that has remained frozen for two or more consecutive years, in most areas' permafrost has been frozen for thousands of years.

Susan Natalie, an associate scientist at WHRC, found that permafrost holds an estimated 1,500 billion tonnes of carbon. This is almost double the carbon that is currently in the atmosphere. Apart from carbon, permafrost also stores large amounts of methane. When permafrost thaws upon heating up of the region, it releases vast amounts of this carbon and methane back into the atmosphere.

In other words, rising temperatures result in permafrost – that is primarily a storage room for carbon and methane – becoming the cause of these gases being emitted back into the atmosphere. Thawing of permafrost is a reality. If it persists, it could result in pervasive global warming. Some scientists find it difficult to determine the relative proportion of carbon emission that might result from permafrost thawing because such a phenomenon has never occurred in human history.

Studies conducted by Nature Climate Change estimate that carbon loss from permafrost regions could increase by 41 per cent if greenhouse gas emissions by humans continue at their current pace. Another study conducted by WHRC in 2017 estimates that if global temperatures rise by 1.5°C, thawing of permafrost could release 68 to 508 gigatons of carbon. Needless to say, these figures indicate catastrophic impacts on climate change from melting of permafrost.

Scientists are concerned that melting of permafrost would result in an “irreversible cycle wherein permafrost releases carbon into the atmosphere; this accelerates the heating up of the earth, which then triggers more permafrost thaw, only for the cycle to repeat itself endlessly. Resultantly, it is perceivable that no human action or inaction will be able to halt this irreversible cycle.

However, significant reduction in emission of greenhouses gases could certainly slow down the rate at which this cycle sets out to destroy the planet. Several problems have arisen upon melting of the permafrost ice. Dormant microbes that have been trapped under the frozen ground for thousands of years have now revived and infected humans with life-threatening diseases.

Scientists believe that bacteria and viruses that have been frozen under permafrost for millions of years can revive when it melts. The possibility of diseases such as Spanish flu, smallpox or the plague, that have been eradicated, could possibly revive upon melting of the permafrost. The world is already dealing with one of the world's worst pandemics. Thawing of permafrost would only make matters worse.

Which of the following words means the same as the word 'pervasive' used in the passage?