How Do Tibetans Survive At High Altitudes Worksheet Answers

If you live in the lowlands, you may have experienced the huffing and puffing that typically accompany a trip to higher altitudes. That’s because oxygen levels go down as one goes up.

Travelling to Denver from sea level means a 17% decrease in available oxygen. Our bodies compensate for even this small change with faster breathing and a higher heart rate — at least until we acclimate to the thinner atmosphere.

What happens when you travel to the mountains?

As you increase elevation the PO2 in the airdrops which affect the pressure in arterial blood (PAO2). The brain detects these changes and sends a message to increase respiration rate, a condition called hyperventilation.

You are likely to take deeper breaths in addition to breathing faster and your heart rate will increase. You may experience dizziness, nausea, fatigue, and headaches.

Low arterial PO2 will cause the release of erythropoietin from the kidneys. EPO will stimulate the bone marrow to produce more red blood cells to increase the concentration of hemoglobin in the blood. This hemoglobin will have the effect of providing tissues with more oxygen.

Extra hemoglobin may compensate for decreased oxygen levels, allowing breathing and heart rate to return to normal. This is an example of phenotypic plasticity, shifts in an organism’s body, physiology, or behavior that are dependent upon the environment it occupies, it is not a genetic change. People can usually acclimate to higher altitudes within a couple of weeks.

  • 1. What does the word “compensate” mean? How does your circulatory system compensate for low levels of oxygen?
  • 2. What is hyperventilation? What are the side effects of hyperventilation?
  • 3. What is the role of your kidneys in compensating for low levels of oxygen?
  • 4. Read the example of phenotype plasticity and provide another example of this phenomenon. Think about this!
  • 5. The following chart compares the hematocrit of blood samples taken from a person at sea level and one at a high altitude. Identify the one at a high altitude and explain your choice.

Some People Didn’t Just Acclimate, They Evolved

Tibetan highlanders have no trouble living at 13,000, and many of them can climb parts of Mount Everest without supplemental oxygen.

How do they do it? New research makes it clear that Tibetan highlanders haven’t just acclimated to their mountain home; they’ve evolved unique physiological mechanisms for dealing with low oxygen levels.

The evolutionary adaptations that allow Tibetans to function at high altitudes are very different from the acclimatization process that most of us go through when we spend time in those places.

One of these adaptations is almost exactly the opposite of a lowlander’s response to high altitude: Tibetans have gene versions that cause them to produce fewer red blood cells.

How is that helpful? It turns out that extra red blood cells make blood thicker — more like honey than water — and after a certain point, this cell-laden blood can actually get so thick that it doesn’t pass through capillaries efficiently to oxygenate cells.

Having blood with too many red blood cells can be particularly problematic during pregnancy since it is linked to slow fetal growth and high rates of fetal mortality.

The basis for the Tibetans’ adaptation is not a change in a gene that produces hemoglobin or any one of the other proteins that make up red blood cells. Instead, the key change seems to be in a stretch of DNA, called EPAS1, which helps control the process of producing red blood cells. The change in EPAS1 seems to make Tibetans less likely to overproduce red blood cells at extreme altitudes.

Biologists compared the genomes of ethnic Tibetans to the genomes of Han Chinese individuals. The basic reasoning was that if a particular gene version was found in Tibetans, but not in their close relatives who lived in the lowlands (Han), then that gene likely arose from natural selection. It was found that the Tibetans were much more likely to have this gene than Han Chinese.

Genetic studies estimate that the Tibetans split from the Han Chinese population and began migrating to the highlands less than 3000 years ago, which means adaptation to living at high altitudes occurred in the population is about a hundred generations. That would represent the fastest example of human evolution ever documented!

  • 6. How is adaptation as observed in the Tibetan population different from acclimatization?
  • 7. What are the consequences of having too many red blood cells?
  • 8. What is EPAS1 and what is its role in the circulatory system?
  • 9. Why did scientists want to compare the genes of Tibetans to the genes of Han Chinese?
  • 10. Scientists examined Tibetans and Han Chinese to compare average hemoglobin (Hb) amounts in the blood.
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GroupAverage [Hb] (g/dL) at high elevationAverage [Hb] (g/dL) at sea level
Lowlanders (Han Chinese)18.515.3
Tibetans15.815.6

Why would scientists want to compare the Hb levels of Tibetans to the two groups of Han Chinese? Summarize the chart above.

  • 11. Does the data support the claim that Tibetans have evolved? Or does it provide evidence that the Tibetans have adjusted? Explain your Reasoning.
  • 12. This table is from an original journal article on altitude adaptation in Tibetans. It shows data from individuals with different versions of the EPAS1 gene. The different gene versions are called “C” and “G.” Remember that humans have two copies of each gene, so this table shows data for people who carry two copies of these gene versions (CC and GG) and for individuals who carry one of each (CG).
  • 13. Which gene version is most likely to be adaptive for Tibetans living at high altitudes? How do you know (reference data in the table)?
  • 14. What is the phenotypic difference between a person with CC genotype and one with CG? How do you think a person with the CG variant would fair at high altitudes?
  • 15. Doctors studied infant mortality rates among Han Chinese population who had moved to Tibet (high altitude).

How many prenatal deaths were recorded for Tibetans? ____ How many for Han? ____

What does “prenatal mortality” mean?

Add another bar to the chart that would represent Han Chinese at low altitudes. Pay attention to the height of the bar and provide a short explanation for your choice.

16. The following graph compares birth weights and postnatal mortality among the two populations. Annotate (Summarize) the graph to explain what it is telling you about the two populations.

Evolution refers to the change in populations over time. This change can be caused by natural selection, where some traits provide an advantage to the individuals, who then pass those traits to their offspring.

How does the evidence about the Tibetans support the claim that humans are evolving? Provide supporting evidence using specific details from this case.

FAQs Tibetans survive high altitudes

How do Tibetans survive high altitudes answer key?

Tibetan populations have actually adapted to high altitudes by producing fewer red blood cells. … Students will discover that blood becomes thicker at high altitudes and that increases the risk of miscarriage and low birth weight. Lowered production of RBC’s is traced to a change in the EPAS1 gene.

How have Tibetans living in high altitudes adapted to their environment?

Instead the Tibetans inhale more air with each breath and breathe more rapidly than either sea-level populations or Andeans. Tibetans have better oxygenation at birth enlarged lung volumes throughout life and a higher capacity for exercise.

What gene version is most likely to be adaptive for Tibetans living at high altitudes?

One of these adaptations is almost exactly the opposite of a lowlander’s response to high altitude: Tibetans have gene versions that cause them to produce fewer red blood cells.

Some People Didn’t Just Acclimate They Evolved.

GroupAverage [Hb] (g/dL) at high elevationAverage [Hb] (g/dL) at sea level
Tibetans15.815.6

What role does the EPAS1 gene play to help Tibetans live at high altitudes?

Researchers discovered in 2010 that Tibetans have several genes that help them use smaller amounts of oxygen efficiently allowing them to deliver enough of it to their limbs while exercising at high altitude. Most notable is a version of a gene called EPAS1 which regulates the body’s production of hemoglobin.

Is Tibet high altitude?

Tibet has an average elevation of roughly 14 370 feet (4 380 meters) above sea level. The number of settlements with a large Han Chinese population peaks at around 8 900 feet (2 700 meters) while Tibetan settlements only begin to peter out beyond 17 000 feet (5 200 meters) the researchers found. See also how many spaces are there in world of light

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Where do the Tibetans live?

Their current population is estimated to be around 6.7 million. In addition to the majority living in Tibet Autonomous Region of China significant numbers of Tibetans live in the Chinese provinces of Gansu Qinghai Sichuan and Yunnan as well as in India Nepal and Bhutan.

How Tibetans survive life on the roof of the world?

At more than 4 000m (13 000ft) above sea level each breath contains around a third less oxygen than the same breath far below. But deep inside each of their bodies within their blood and DNA an ancient and unique trick to surviving at altitude protected them from the thin air in which they built their home.

How do you survive high altitude?

Top 7 Tips for Altitude Sickness Prevention

  1. Climb slowly. Your body needs about two to three days of slowly going higher in order to adjust to the changes. …
  2. Eat carbs. It’s not often we’re told to eat extra carbohydrates. …
  3. Avoid alcohol. …
  4. Drink water. …
  5. Take it easy. …
  6. Sleep lower. …
  7. Medication. …
  8. Symptoms of altitude sickness.

How do people survive in high altitude?

At high altitudes the air is much thinner than at sea level. As a result a person inhales fewer oxygen molecules with each breath. … Having more hemoglobin to carry oxygen through the blood system than people at sea level counterbalances the effects of hypoxia.

How do animals adapt to high altitude?

Scott explains this is in part because high altitude animals have aerobic muscles with a high number of mitochondria – the organelles in cells that generate energy. As well they have more blood vessels to support the supply of oxygen to their tissues.

Is there a genetic basis for adapting to life at high altitudes?

Humans have adapted to the chronic hypoxia of high altitude in several locations and recent genome-wide studies have indicated a genetic basis. … High-altitude adaptation may be due to multiple genes that act in concert with one another.

Did Tibetans evolved or adjust?

Researchers say that Tibetans underwent the fastest genetic changes seen yet in humans during their adaptation to life at high altitudes. The most rapid genetic change showed up in the EPAS1 gene which helps regulate the body’s response to a low-oxygen environment. …

What is EPAS1 and why do Tibetans need EPAS1?

A high percentage of Tibetans carry an allele of EPAS1 that improves oxygen transport. The beneficial allele is also found in the extinct Denisovan genome suggesting that it arose in them and entered the modern human population through hybridization.

What does the EPAS1 gene do?

The EPAS1 gene often known as HIF2A provides instructions for making a protein called hypoxia-inducible factor 2-alpha (HIF-2α). This protein is one part (subunit) of a larger protein complex called HIF which plays a critical role in the body’s ability to adapt to changing oxygen levels.

Are Tibetans better athletes?

Tibetans have a gene EPAS1 that’s known to help regulate how the body responds to low oxygen levels. “It’s also been called the ‘super athlete gene ’ because we know that certain humans that have a special version of this gene have a better performance with certain types of athletics ” says Nielsen.

How do people survive in Tibet?

People who live or travel at high altitude respond to the lack of oxygen by making more hemoglobin the oxygen-carrying component of human blood. … Tibetans maintain relatively low hemoglobin at high altitude a trait that makes them less susceptible to the disease than other populations.

How do Tibetans heat their homes?

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Most Tibetan homes don’t have gas or oil heating and kerosene and wood are in short supply. Yak dung is often burned for cooking and heating. Most houses are sealed except for small hole in the ceiling that lets out some smoke but also allows some rain or snow to enter.

What’s the highest altitude a human can survive?

An elevation of about 20 000 feet above sea level is the maximum height at which sufficient oxygen exists in the air to sustain us.

Why does China want Tibet?

There are also strategic and economic motives for China’s attachment to Tibet. The region serves as a buffer zone between China on one side and India Nepal and Bangladesh on the other. The Himalayan mountain range provides an added level of security as well as a military advantage.

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How many Chinese killed Tibetans?

1.2 million Tibetans   The 14th Dalai Lama has alleged that 1.2 million Tibetans were killed under Chinese rule.

Which country is called roof of the world?

Tibetan
Central Asia’s Tibetan Plateau is justifiably nicknamed “the roof of the world”-its average elevation is more than 4 500 meters (14 764 feet).Sep 17 2007

What altitude do Tibetans live?

People of Tibetan ethnic descent are lifelong high-altitude residents and cannot easily move to higher or lower elevations. Over 90% of the population are engaged in farming and herding. The upper altitude limit of crops is around 4500 m while the nomads reside above 4800 m and 5500 m.

Why do you get altitude sickness in Tibet?

Despite it being cold on the Tibetan plateau the climate can still cause severe dehydration which is one of the main causes of the symptoms of altitude sickness.

Who lives in the Tibetan mountains?

Tibetan people are the inhabitant of the Qinghai-Tibet plateau. They are descended from the ancient Qiang people. More than 4 000 years ago the ancestors of the Tibetan people flourished in the Brahmaputra Valley.

What are the 3 stages of acclimatization to high altitude?

We divided the time at altitude into nine periods with three stages from the preparation for ascent to a high altitude to the time after soldiers descend to a low altitude (Fig. 1). The three stages are the preparation stage the ascent stage and the descent stage.

Does high altitude make you fart?

Australian researchers found the farts occur at altitudes as low as 5 900 feet and that flatus frequency tends to peak around eight and 11 hours after a rapid ascent. Rapid meaning you got there in a day from a much lower altitude.

How do you breathe at high altitudes?

Once you’ve mastered the belly breath you can add resistance to your exhalation by pursing your lips and exhaling forcefully and this is what mountaineers call the Pressure Breath. This is one of the most important breaths for climbing at high altitudes and helps combat the decrease in atmospheric pressure. See also Why Do Lakes Turnover?

What animals live at high altitude?

  • Brown Bear (Ursus arctos)
  • Himalayan Tahr (Hemitragus jemlahicus)
  • Lammergeier (Gypaetus barbatus)
  • Tibetan sand fox (Vulpes ferrilata)
  • Himalayan Marmot (Marmota himalayana)
  • Kiang (Equus kiang)
  • Chiru (Pantholops hodgsonii)
  • Tibetan gazelle (Procapra picticaudata)

Can snakes survive at high altitudes?

High altitudes are known for being colder. Because snakes do not generate their own heat cold temperatures can make them sluggish and interfere with their digestion. They will not immediately become helpless but if they can’t maintain enough heat in their bodies they will stop moving and eventually die.

Which mammal lives at the highest altitude?

Among domesticated animals yaks (Bos grunniens) are the highest dwelling animals of the world living at 3 000–5 000 metres (9 800–16 400 ft).

Why do you think animals living in high altitude have thick fur?

Mountains at very high altitudes also witness regular snowfall during winters. Animals such as snow leopard yaks etc. which live in mountains have thick skins or furs that protect them from cold. Furs can also be present on the feet and toes of these animals.

What happens to the body at high altitude?

At high altitudes oxygen molecules are further apart because there is less pressure to “push” them together. This effectively means there are fewer oxygen molecules in the same volume of air as we inhale. In scientific studies this is often referred to as “hypoxia”.

Which one is a physiological adaptation at high altitude?

Altitude exposure is associated with major changes in cardiovascular function. The initial cardiovascular response to altitude is characterized by an increase in cardiac output with tachycardia no change in stroke volume whereas blood pressure may temporarily be slightly increased.

Which of the following is an adaptation at higher altitude?

Physiological adaptations to high-altitude

One of the classic examples of adaptation to a novel environment is adaptation to high-altitude. At high-altitude differences in barometric pressure result in insufficient oxygen in the air thereby causing hypoxia (that is reduced oxygen levels in the blood).

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