Lichens (地衣)
Lichens look like splashes of paint left behind by a careless painter. Unlike many plants, they do not require soil to grow. They grow on trunk of trees in steaming tropical rain forests, on farmers’ fenceposts, on the bricks of big-city buildings, and on old gravestones. Lichens can tolerate extremes of climate. They grow on rocks in hot springs, on wind-swept mountaintops, and on stones in the driest deserts. In the Arctic, lichens are the principal source of food for reindeer. Whole mountainsides in Antarctica appear green and orange because of the presence of lichens; they are one of the few plants that can survive there. They are among the oldest of known plants. Recently, scientists discovered lichen fossils on a rock in a mine in southwest China that date back 600 million years.
When conditions become harsh, lichens become dormant (休眠). If there is not enough moisture, they simply dry up, but a short rain or even a heavy dew gives them new life. When growing on rock surfaces, lichens produce acids that dissolve (溶解) the minerals, contributing to the process of weathering by which rocks are slowly turned to soil. This property enables lichens to be pioneers. They appear on barren rock rubbed clean by glaciers, fires, lava flows, or floods, beginning the process of soil formation that allows mosses (苔藓) and other plants to later take root. But, despite their hardiness, lichens are extremely sensitive to airborne particles(颗粒). That’s why they serve as an early warning system for air pollution.
It is the acids lichens produce that give them their distinctive colors. Lichens are often spoken of in the same breath as mosses, and some lichens are even called mosses, but true mosses are all distinctively green, whereas lichens appear in many vivid colors. At one time, acids from lichens were used to make dyes, such as the purple dye, the blue dye, and the red dye, and they are sometimes still used that way today. Some lichens, such as oakmoss, contain oils that produce fragrant odors used in scented soaps, cosmetics and perfumes. Some lichens are also known to have antibiotic properties to kill bacteria.
So definite are the form, color, and characteristics of these organisms that for hundreds of years lichens were constantly under scientists’ microscope.
1. What characteristic of lichens is mainly talked about in paragraph 1?| A．They grow only on rock surfaces. |
| B．They live primarily in cold places. |
| C．They have adapted to a wide variety of environments. |
| D．They live in remote locations far from human communities. |
| A．have their primitive structure |
| B．grow in areas before other plants do |
| C．are found in remote parts of the world |
| D．develop so early in the history of the planet |
| A．as a means of coloring clothing |
| B．as a type of medicine |
| C．as a source of food |
| D．as an ingredient in perfume |
| A．Lichens are important in Canada because of their abundance in the north. |
| B．Extracts of lichens were sold as herbal medicines to facilitate hair growth. |
| C．Glacier Park’s vast array of lichens indicate relatively good air quality. |
| D．A German botanist first found lichens are composed of two life forms. |
相似题推荐
【推荐1】An artificial intelligence that navigates (导航) its environment much like mammals could help solve a mystery about our own internal GPS.
Equipped with virtual versions of specialized brain nerve cells called grid(网格) cells, the AI could easily solve and plan new routes through virtual mazes (迷宫). That performance, described online May 9 in Nature, suggests the grid cells in animal brains play a critical role in path planning.
“This is a big step forward in understanding our own navigational neural circuitry(电路),”says Ingmar Kanitscheider, a computational neuroscientist at the University of Texas at Austin not involved in the work. The discovery that rats track their location with the help of grid cells earned a Norwegian research team the 2014 Nobel Prize in physiology to medicine. Neuroscientists suspected these cells, which have also been found in humans, might help not only give mammals an internal, coordinate(协同) system, but also plan direct paths between points.
To test that idea, neuroscientist Caswell Barry at University College London, along with colleagues at Google DeepMind, created an AI that contained virtual nerve cells, or neurons, whose activity resembled that of real grid cells. The researchers trained this AI to navigate virtual mazes by giving the system reward signals when it reached its destination.
The AI bested a human expert player at solving the virtual mazes, and proved savvier than other artificial neural networks in planning ways through mazes larger than those traversed (横穿的) during its training. When a door opened to provide a shortcut through the maze, the new AI took the more direct route. By contrast, AI systems without artificial grid cells ignored the open door and took long the way around.
These findings support the idea that grid cells do more than help mammals orient themselves in time and space; they also help animals plan the most straightforward direction to destinations. AI also appears to be “a very powerful tool” for testing other neuroscience theories, Barry says. He and his colleagues suggest that virtual experiments on artificial neural networks that imitate different regions of the brain may eventually replace some animal testing.
But there are limitations to using AI to study the brain. Because the system is meant to learn on its own, researchers can't tell why the system made a specific decision, says neuroscientist Francesco Savelli at Johns Hopkings University, whose commentary also appears online May 9 in Nature.
1. What's the function of the virtual grid cells?| A．Assisting the AI in finding a way-out. |
| B．Controlling the growth of nerve cells. |
| C．Helping animals adapt to the environment. |
| D．Promoting the cooperation between AI robots. |
| A．slower | B．wiser | C．earlier | D．quicker |
| A．Animals are as intelligent as humans. |
| B．Grid cells are more important than other nerve cells. |
| C．Humans will be equipped with the virtual grid cells. |
| D．Animal testing on the brain will be reduced in future. |
| A．How the AI system works. |
| B．Ways of AI learning on its own. |
| C．How effective reward signals will work on a robot. |
| D．The relationship between different regions of the brain. |
【推荐2】In the early 1980s，an American engineer Chuck Hull went to his boss with an idea：to build a machine that prints out things you can hold in your hand. His manager told him that the company produced UV lamps, not machines that were able to make copies of things of all kinds. But finally they reached an agreement. Hull would spend the day working on the company’s lamps；at night he’d work on his machine.
It was the UV lights that gave Hull the idea at first. The lamps were used in factories to harden a plastic veneer（薄片镶饰）. Hull realized that he could use UV lights to cut plastic pieces into whatever shape he liked and then pile these pieces to form a 3-D thing. Then he had to write programs to tell his machine how to cut each piece. At last，his first 3-D printer was put together.
But by the mid-1980s，the printer had developed into a working product，though it cost hundreds of thousands of dollars. Because the printer was too heavy to carry to exhibitions，Hull made home movies to show it to people. “The movies were pretty boring，but even so，”he said，“we got a strong reaction，especially in Detroit. Back then，the US car industry had been far behind Japan and the car companies were eager for a secret weapon（武器）. “The 3-D printer was just that：engineers could make their own models for parts such as door handles（把手），rather than send plans to a tool and dye shop，saving months during the design process and thus making their cars more competitive.
Now that the technology is becoming affordable，all kinds of people have caught 3-D fever. A professor from the University of California is working on printing out an entire house. Another 3-D artist has made a robotic hand that lets his son，who was born without several fingers，pick up a water bottle. “Anything that can be made will be made by anyone anywhere，”wrote Joris Peels，a 3-D pioneer. “Anyone will be able to 3-D-print a spoon，a truck or a rose. ”
1. What was Hull？| A．An engineer working for a lamp company. |
| B．A worker in a printer company. |
| C．A professor from the University of California. |
| D．A moviemaker. |
| A．Because he didn’t want people to know too much about it. |
| B．Because it was too heavy. |
| C．Because it still could not work. |
| D．Because it was too expensive. |
| A．It has a bright future. |
| B．It is difficult for people to use. |
| C．It still needs improving. |
| D．It will be used as a powerful weapon. |
| A．To introduce an engineer. |
| B．To make us know how the 3-D printer was invented. |
| C．To advertise for a printer company. |
| D．To tell us that a lamp company can also make printers. |
【推荐3】Microsoft plans to erase its entire carbon footprint since its foundation in 1975. Microsoft aims to accomplish "carbon negative" by 2030, meaning that it will erase more carbon from the environment than it emits(排放). The company will minimize carbon emissions across its entire supply chain to zero. And the following step is to clean up all the carbon emissions it has produced since 1975, when it was founded. What the company further proposed was that it would try to push for policies to price carbon and help clean energy technology develop faster. It is among the companies that approve of carbon tax.
More attention has been drawn to removing carbon from the atmosphere. There are a variety of methods toward that, including nature-based ones, like planting trees, and technological ones, like capturing carbon directly from the air.
“Microsoft will initially focus on nature-based methods like restoring degraded forests and planting new trees, ”said Lucas Joppa, the company's Chief Environmental Officer. An investment of one billion dollars will also be provided for the development of carbon removal and reduction technology. Microsoft's decision of counting its supply chain's emissions is an extension of its previous commitment to run data centers mainly on the renewable energy.
The company's intention to promote low-carbon policies was highly recognized by environmentalist. “A company's most powerful tool for fighting climate change is its political influence, and we're eager to see Microsoft use it, ”Elizabeth Sturcken, Managing Director of EDF+Business said.
Other industries are also encouraged to follow Microsoft's example. But none of them has such a commitment, according to Gary Cook, senior analyst of Greenpeace. Nevertheless, Cook, together with some other environmentalists, criticized Microsoft for continuously cooperating with oil and gas companies. Amazon's AWS service has faced the same criticism for working with fossil fuel clients.“There's a real disconnection between what they're doing within their own company and their empowering of dirty energy, ” Cook said.
1. What do we know about Microsoft In its “carbon negative” commitment?| A．It will reduce its carbon emissions to almost zero. |
| B．It will remove all the carbon from the environment. |
| C．It plans to clean up its previously released carbon. |
| D．It plans to include its clients in its future campaign. |
| A．Collecting carbon tax | B．Capturing carbon from the air |
| C．Exploring renewable resources | D．Funding carbon reduction technology |
| A．They criticize it for its unrealistic promise. |
| B．They think highly of it for its political influence. |
| C．They praise it for its push for low-carbon policies |
| D．They speak ill of it for its partnership with Amazon. |
| A．Health. | B．Politics | C．Technology. | D．Environment. |
【推荐1】High-resolution (高分辨率) satellite imagery has been used to map every single tree in Africa, showing a technique that could help improve the monitoring of deforestation (森林砍伐) across the world. Florian Reiner at the University of Copenhagen, Denmark, and his colleagues used images from sate lies to map canopy (树冠) across the entire African continent.
Modern sate lies usually catch tree canopies at a resolution of 30 meters — fine for measuring the size of forests, but less good at mapping individual trees. The satellite data Reiner and his colleagues used had a resolution of 3 meters, enabling the study to map all trees, including those not part of a forest.
The results suggest that 30 percent of all trees in Africa aren’t in a forest and instead are across farmland, savannah and urban areas. “Many countries in Africa lack thick forests, but have a lot of trees.” says Reiner. “These trees are extremely important to the local ecosystems, the people and the economy. By tracking every single tree, researchers can start to monitor how these trees are coping with climate change or whether they are sensitive to deforestation.” It could also improve the monitoring of reforestation efforts, which are growing in popularity as a way of removing carbon dioxide from the atmosphere.
“At a local level, being able to consistently monitor when and where trees are disappearing or reappearing can lead to more actionable insights,” says John Francis at the Alan Turing Institute in London.
“The study is a proof of concept rather than a map ready for immediate commercial use,” says Reiner. “It’s research work. It’s showing what could be done,” he says. But he is already working with colleagues to scale up the tracking approach to cover the entire global canopy: “We’re hoping that this will be seen as a way forward in monitoring tree resources.”
1. Why is high-resolution satellite imagery used to map every single tree?| A．To know the exact height of the tree. |
| B．To have a clear picture of the canopy. |
| C．To help monitor the deforestation. |
| D．To improve the satellite technology. |
| A．Doubtful. | B．Disapproving. | C．Indifferent. | D．Favorable. |
| A．Protect the trees only in Africa. |
| B．Put the map into commercial use. |
| C．Track the entire global canopy. |
| D．Improve the imagery technology. |
| A．Ways to Measure the Size of Forests in Africa |
| B．Coping with Climate Change by Tracking Every Single Tree |
| C．A Map from the Satellite Ready for Immediate Commercial Use |
| D．High-resolution Satellite Imagery Used in Monitoring Deforestation |
【推荐2】An ancient plant, amaranth(苋菜),is drawing attention throughout the world and connecting indigenous people(土著人)to their history. It has become a billion-dollar food and cosmetic product since the 1970s. The ancient grain can be found in greater numbers of grocery stores in the US and Mexico, and increasingly in the Asia Pacific and Europe.
“This is a plant that could feed the world.” Beata Tsosie-Pena, a coordinator of the environmental, health and justice program at nonprofit Tewa Women United, told The Guardian.
Amaranth is actually a grain, like buckwheat, and native to Mesoamerica, a region including southern Mexico and many counties in Central America. Its seed is a highly nutritious source of protein, vitamins and minerals. It’s proved to be an attractive product for health-conscious shoppers.
A single amaranth plant produces hundreds of seeds and can be grown in a wide variety of climates and countries from India, China, Southeast Asia to West Africa and the Caribbean. It’s this resilience that allowed the plant to survive over the centuries, even when the Spanish arrived in the Americas in the 16th century and outlawed amaranth. Growing amaranth has also provided a degree of economic independence for indigenous farmers in Guatemala and the US, according to The Guardian. Even after facing a near-extinction event in Guatemala when state forces targeted the Maya people and burned their fields, farmers preserved their amaranth seeds by hiding them in jars in the field and under their floorboards.
“What we want is for the whole world to produce their own food,” Maria Aurelia Xitumul, a. member of agricultural community Qachuu Aloom, told The Guardian. ”For the seeds, distance doesn’t exist. Borders don’t exist.” Most recently, Xitumul said that during the pandemic, people with their own gardens, especially in locked down communities, felt secure knowing they had control over their food supply, thanks to amaranth.
“Amaranth has completely changed the lives of families in our communities, not only economically, but spiritually,” added Xitumul.
1. What do we know-about amaranth?| A．It was found in Mesoamerica in the 1970s. |
| B．It mainly grows in the Americas and Europe. |
| C．Its seed contains abundant vitamins and minerals. |
| D．It’s one of the most expensive foods in the world. |
| A．Its ability to produce many seeds. |
| B．Its function of offering economic independence. |
| C．The quality of growing quickly in extreme weather. |
| D．Its ability to adjust to different environments. |
| A．Plants should be grown in line with local conditions. |
| B．Countries should work together to promote the seeds. |
| C．Amaranth gave people a sense of security during lockdown. |
| D．Amaranth helped lift many families out of poverty. |
| A．The Origin of Amaranth. |
| B．The Value of Amaranth. |
| C．The Popularity of Amaranth. |
| D．The Wide Application of Amaranth. |
【推荐3】Would it surprise you to learn that, like animals, trees communicate with each other and pass on their wealth to the next generation?
UBC Professor Simard explains how trees are much more complex than most of us ever imagined. Although Charles Darwin thought that trees are competing for survival of the fittest, Simard shows just how wrong he was. In fact, the opposite is true:trees survive through their co-operation and support, passing around necessary nutrition “depending on who needs it”.
Nitrogen and carbon are shared through miles of underground fungi networks, making sure that all trees in the forest ecological system give and receive just the right amount to keep them all healthy. This hidden system works in a very similar way to the networks of neurons in our brains, and when one tree is destroyed, it affects all.
Simard talks about“mother trees”, usually the largest and oldest plants on which all other trees depend. She explains how dying trees pass on the wealth to the next generation, transporting important minerals to young trees so they may continue to grow. When humans cut down “mother trees” with no awareness of these highly complex “tree societies”or the networks on which they feed, we are reducing the chances of survival for the entire forest.
“We didn’t take any notice of it,” Simard says sadly. “Dying trees move nutrition into the young trees before dying, but we never give them chance.” If we could put across the message to the forestry industry, we could make a huge difference towards our environmental protection efforts for the future.
1. The underlined sentence “the opposite is true” in Paragraph 2 probably means that trees________.| A．struggle for survival |
| B．protect their own wealth |
| C．depend on each other |
| D．provide support for dying trees |
| A．look the smallest in size in the forest |
| B．pass on nutrition to young trees |
| C．seem more likely to be cut down by humans |
| D．know more about the complex “tree societies” |
| A．how “tree societies” work |
| B．how trees grow up. |
| C．how young trees survive |
| D．how forestry industry develops |
| A．Old Trees Communicate Like Human being |
| B．Protect Young Trees In Need |
| C．Trees Are More Awesome Than You Think |
| D．Trees Contribute To Our Society |
