A breathtaking trick potentially left over from our ancestors might be found in us — the ability to sense oxygen through our skin.
Amphibians, animals such as frogs that can live both on land and in water, have long been known to be capable of breathing through their skin. In fact, the first known lungless frog that breathes only through its skin was discovered recently in the rivers of Borneo.
Now the same oxygen sensors found in frog skins and in the lungs of mammals (哺乳动物) have unexpectedly been discovered in the skin of mice.
“No one had ever looked,” explained Randall Johnson, a biologist researcher.
Mice and frogs are quite distant relatives, so the fact they have these molecules (分子) in common in their skin suggests they might well be found in the skin of other mammals, such as humans.
“We have no reason to think that they are not in the skin of people too,” Johnson said.
These molecules not only detect oxygen, but help increase levels of vital red blood cells, which carry oxygen around the body. Normal mice breathing in air that is 10 percent oxygen—a dangerously low level similar to conditions at the top of Mount Everest, and about half that of air at sea level. However, mice that had the oxygen sensor HIF-1a genetically removed from their skin failed to produce this hormone (荷尔蒙) even after hours of such low oxygen.
These findings, if they hold true in humans, suggest one could raise the level of oxygen circulating inside the body. This could help treat lung diseases and disorders such as anemia (贫血症) without injecting drugs, which make up a multibillion-dollar market, Johnson said.
Athletes also often try to get more oxygen delivered to their muscles in order to improve their performance. They often do this by training at high altitudes or in low-oxygen tents. The new study suggests they might want to expose their skin as well as breathing in low-oxygen air to improve their performance. “It’s hard to say what exactly might be done, however—there’s a lot we don’t know yet,” Johnson explained.
The scientists detailed their findings in the April 18 issue of the journal Cell.
【小题1】Which of the following statements is TRUE according to the passage?

Can you remember a morning when you’ve woken up to the ring of your alarm clock and wished you could stay in bed? You haven’t slept well, your hair is a mess. Worse, you can’t stop yawning. Yawning is universal to humans and many animals. Cats, dogs and fish yawn just like humans do! Yawning is an involuntary(无意识的,不自觉的) action during which you open your mouth and breathe deeply. The average duration of a yawn is about 6 seconds.
The purpose and cause of yawning are still a mystery. Scientists are not sure what causes a yawn. People yawn when they are tired or bored, but they also yawn when they aren’t. There are many ideas explaining why we yawn.
One idea is that yawning is a way for the body to become more alert by taking in more oxygen. A yawn increases the heart rate, forces carbon dioxide out of the lungs and blood stream, and brings oxygen to the brain. But one study showed that volunteers given a lot of oxygen did not yawn any less than before, while those given a lot of carbon dioxide did not yawn more.
Another idea is that early humans used yawning as a form of communication. If one decided it was time to sleep, they would tell the others by yawning and they would do it in return to show they agreed.
A third explanation comes from psychology professor Gordon Gallup of University at Albany in New York. He said that as people yawn, they cool off their brains. “Brains are like computers.” he said. “They only operate efficiently and effectively when they’re cool. Many things connected to yawning, like being tired, make the brain hot, and yawning can reduce the heat.”
Scientists have sent people into space, and created terrible nuclear weapons, but there are lots of seemingly simple things, such as why we yawn, or hiccup（打嗝）, that they can’t figure out. Next time you are in class in the morning, let out a big yawn and watch to see how many of your classmates yawn in response!
【小题1】What’s the purpose of the description of how bad you may feel when you’re woken up in the morning?

从A、B、C、D四个选项中，找出其划线部分与所给单词的划线部分读音相同的选项。

1.realize        A. pyramid       B. responsibly       C. whisper       D. title

2.produce    A. distance    B. dictation         C. increase     D. courage

3.rather         A. bath          B. thinking          C. feather      D. something

4.oxygen    A. damage        B. degree            C. recognize    D. sugar

5.regular     A. apartment       B. park          C. similar          D. hardship

Aluminum isn’t found free in nature, owing to its always ____ with other elements, most commonly with oxygen.

A breathtaking trick potentially left over from our ancestors might be found in us — the ability to sense oxygen through our skin.

Amphibians, animals such as frogs that can live both on land and in water, have long been known to be capable of breathing through their skin. In fact, the first known lungless frog that breathes only through its skin was discovered recently in the rivers of Borneo.

Now the same oxygen sensors found in frog skins and in the lungs of mammals (哺乳动物) have unexpectedly been discovered in the skin of mice.

“No one had ever looked,” explained Randall Johnson, a biologist researcher.

Mice and frogs are quite distant relatives, so the fact they have these molecules (分子) in common in their skin suggests they might well be found in the skin of other mammals, such as humans.

“We have no reason to think that they are not in the skin of people too,” Johnson said.   These molecules not only detect oxygen, but help increase levels of vital red blood cells, which carry oxygen around the body. Normal mice breathing in air that is 10 percent oxygen—a dangerously low level similar to conditions at the top of Mount Everest, and about half that of air at sea level. However, mice that had the oxygen sensor HIF-1a genetically removed from their skin failed to produce this hormone (荷尔蒙) even after hours of such low oxygen.

These findings, if they hold true in humans, suggest one could raise the level of oxygen circulating inside the body. This could help treat lung diseases and disorders such as anemia (贫血症) without injecting drugs, which make up a multibillion-dollar market, Johnson said.

Athletes also often try to get more oxygen delivered to their muscles in order to improve their performance. They often do this by training at high altitudes or in low-oxygen tents. The new study suggests they might want to expose their skin as well as breathing in low-oxygen air to improve their performance. “It’s hard to say what exactly might be done, however—there’s a lot we don’t know yet,” Johnson explained.

The scientists detailed their findings in the April 18 issue of the journal Cell.

49. Which of the following statements is TRUE according to the passage?

A. Johnson believes that Oxygen sensors also exist in human skin.

B. People have to surf the Internet to read detailed findings.

C. It has been proved that these findings help treat lung diseases.

D. It has long been expected oxygen sensors exist in mice’s skin. 

50. One of the functions of the molecules mentioned above is _______.

A. carrying oxygen around the body                   B. improving athletes’ performance

C. detecting oxygen                                          D. increasing level of oxygen

51. What is Johnson’s attitude to the application of the findings to the athletes’ training?

A. Negative                  B. Doubting                  C. Positive             D. Hesitating

52. The best title of the passage may be _______.

A. Great Findings Benefits Athletes A Lot

B. Frogs And Mice Are Distant Relatives

C. First Known Animal Breathes Through Skin

D. Humans Might Sense Oxygen Through Skin