Book 1 Reading and Speaking (1108795), страница 15
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Give detailed answers to the following questions using the information from the text:1. Why do birds migrate?2. What adaptations allow birds to accomplish their migrations? Describe each in detail.3. How are migratory birds different from non-migratory species?4. How do birds prepare for the hardships of migration?5. What is Zugunruhe?Exercise 6. In the following text the paragraphs are mixed.
Put them in the correct logical order. The firstparagraph is in its right place.How do deep-diving sea creatures withstand huge pressure changes?Paul J. Ponganis and Gerald L. Kooyman of the Center for Marine Biotechnology and Biomedicine at ScrippsInstitution of Oceanography provide the following answer.A sperm whale can dive down more than 2,000 meters and can stay submerged for up to an hour.(A) Some sea creatures exploit great depths. The biggest physiological challenges in adapting to pressureare probably faced by those animals that must routinely travel from the surface to great depth. Two such animalsare the sperm whale and the bottlenose whale. From the days of whaling, these animals have been recognized asexceptional divers, with reports of dives lasting as long as two hours after they were harpooned. Today, with theuse of sonar tracking and attached time-depth recorders, dives as deep as 6,000 feet (more than a mile below thesurface of the ocean) have been measured.
Routine dive depths are usually in the 1,500- to 3,000-foot range, anddives can last between 20 minutes and an hour.(B) Loss of gas exchange at depth has another important implication: the lungs of the deep diver cannotserve as a source of oxygen during the dive. Instead deep-diving whales and seals rely on large oxygen stores intheir blood and muscle. Several adaptations enable this. First, these animals have mass specific blood volumesthat are three to four times those found in terrestrial mammals (i.e., 200 to 250 milliliters of blood per kilogram bodymass, in contrast to a human value of 70 milliliters blood per kilogram). Second, the concentration of hemoglobin(the oxygen-transport protein in blood) is also elevated to a level about twice that found in humans.
Third, theconcentration of myoglobin, the oxygen storage protein in muscle, is extremely elevated in these animals,measuring about 10 times that in human muscle.(C) In summary, the primary anatomical adaptations for pressure of a deep-diving mammal such as thesperm whale center on air-containing spaces and the prevention of tissue barotrauma. Air cavities, when present,are lined with venous plexuses, which are thought to fill at depth, obliterate the air space, and prevent "thesqueeze." The lungs collapse, which prevents lung rupture and (important with regard to physiology) blocks gasexchange in the lung. Lack of nitrogen absorption at depth prevents the development of nitrogen narcosis anddecompression sickness. In addition, because the lungs do not serve as a source of oxygen at depth, deep diversrely on enhanced oxygen stores in their blood and muscle.(D) Diving to depth can result in mechanical distortion and tissue compression, especially in gas-filled spacesin the body.
Such spaces include the middle ear cavity, air sinuses in the head, and the lungs. Development ofeven small pressure differentials between an air cavity and its surrounding tissue can result in tissue distortion anddisruption—a condition in human divers known as "the squeeze." In some species of cetaceans, the middle earcavity is lined with an extensive venous plexus, which is postulated to become engorged at depth and thus reduceor obliterate the air space and prevent development of the squeeze. Cetaceans also have large Eustachian tubescommunicating with the tympanic cavity of the ear and the large pterygoid sinuses of the head.
These air sinuses ofthe head have an extensive vasculature, which is thought to function in a manner similar to that of the middle earand facilitate equilibration of air pressure within these spaces. Lastly, most marine mammals lack frontal cranialsinuses like those present in terrestrial mammals.(E) Collapse of the lungs forces air away from the alveoli, where gas exchange between the lungs and bloodoccurs. This blunting of gas exchange is important in the deep diver because it prevents the absorption of nitrogeninto the blood and the subsequent development of high blood nitrogen levels.
High blood nitrogen pressures canexert a narcotic effect (so-called nitrogen narcosis) on the diver. It may also lead to nitrogen bubble formationduring ascent—a phenomenon known as decompression sickness or "the bends." Collapse of the lungs in the deepdiver avoids these two problems.(F) Another organ susceptible to compression damage is the lung.
In deep-diving whales and seals, theperipheral airways are reinforced, and it is postulated that this allows the lungs to collapse during travel to depth.Such collapse has been observed radiographically and confirmed with blood nitrogen analyses in the deep-divingWeddell seal.Exercise 7. Make up a list of the 10 key terms used in the text, then agree with the whole group on the finallist. Retell the article using these terms.Exercise 8. Prepare your own report about adaptations of other species to their habitat and lifestyle.36Section 2. Recommended Report and Presentation Topics1. Mental disorders.2. Brain regions and their functions.3.
What exactly are dreams?4. Dreams and nightmares.5. Early bird or night owl?6. Coffee – friend or foe? Health effects of coffee.7. Decaffeinated coffee.8. Tea or coffee?9. Eugenics.10. Gene therapy.11. GM plants.12. GM animals.13. Engineered animals and natural populations.14. Animal conservation.15. Ecotourism.37Section 3.Unit 11. Human EvolutionThe species does not grow into perfection: theweak again and again get the upper hand of thestrong,—their large number, and their greatercunning are the cause of it.Friedrich NietzscheExercise 1. What is evolution?1. Why is Africa considered the birthplace of Homo sapiens?2.
What is the difference between monocentrism and polycentrism?3. What caused bipedalism (bipedal locomotion) and upright posture in humans?4. Why do people living in the south tend to have dark skin colour, while people living in the north have faircomplexion?5. How did human races originate?6. What factors can speed up evolution?Exercise 2. Explain the meaning of the following key terms connected with evolution:natural selectionmutationvariationatavismhereditynorm of reactionrudimentselective breedingspeciesdivergencecompetitiongenotypepopulationconvergencebiological progressphenotypeecological nicheparallelismbiological regressionadaptationExercise 3.
Now read the article to check some of your answers in Exercise 1.Culture Speeds Up Human EvolutionAnalysis of common patterns of genetic variation reveals that humans have been evolving faster in recenthistoryBy David BielloHomo sapiens sapiens has spread across the globe and increased vastly in numbers over the past 50,000years or so—from an estimated five million in 9000 B.C.
to roughly 6.5 billion today. More people means moreopportunity for mutations to creep into the basic human genome and new research confirms that in the past 10,000years a host of changes to everything from digestion to bones has been taking place."We found very many human genes undergoing selection," says anthropologist Gregory Cochran of theUniversity of Utah, a member of the team that analyzed the 3.9 million DNA sequences* showing the mostvariation. "Most are very recent, so much so that the rate of human evolution over the past few thousand years isfar greater than it has been over the past few million years." "We believe that this can be explained by an increasein the strength of selection as people became agriculturalists—a major ecological change—and a vast increase inthe number of favorable mutations as agriculture led to increased population size," he adds.Roughly 10,000 years ago, humanity made the transition from living off the land to actively raising crops anddomesticated animals.
Because this concentrated populations, diseases such as malaria, smallpox andtuberculosis, among others, became more virulent. At the same time, the new agriculturally based diet offered itsown challenges—including iron deficiency from lack of meat, cavities and, ultimately, shorter stature due to poornutrition, says anthropologist John Hawks of the University of Wisconsin–Madison, another team member. "Theirbodies and teeth shrank.
Their brains shrank, too," he adds. "But they started to get new alleles that helped themdigest the food more efficiently. New protective alleles allowed a fraction of people to survive the dread illnessesbetter."By looking for wide swaths of genetic material that vary little from individual to individual within these sectionsof great variation, the researchers identified regions that both originated recently and conferred some kind ofadvantage (because they became common rapidly). For example, the gene known as LCT gave adults the ability todigest milk and G6PD offered some protection against the malaria caused by Plasmodium falciparum parasite."Ten thousand years ago, no one on planet Earth had blue eyes," Hawks notes, because that gene—OCA2—hadnot yet developed.
"We are different from people who lived only 400 generations ago in ways that are very obvious;that you can see with your eyes."Comparing the amount of genetic differentiation between humans and our closest relatives, chimpanzees,suggests that the pace of change has accelerated to 10 to 100 times the average long-term rate, the researcherswrite in Proceedings of the National Academy of Sciences USA.
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