1 . When micro-plastics end up in farm fields, the pollution can damage plant growth. But two young researchers now report that combining fungi (真菌) with certain farm wastes can partly overcome that problem.
May Shin, 20, and Jiwon Choi, 18, met in a research design class at the Fryeburg Academy, a high school in Maine. May had desired to explore how micro-plastics might affect the ecosystem. Jiwon was crazy about plants and fungi. The young scientists cooperated to test how long-lived plastics might affect farm crops.
Scientists have shown certain fungi can aid root growth and a plant’s nutrient uptake. Those organisms are named arbuscular mycorrhizal fungi (AMF). Certain farm wastes, like straw, can provide nutrients to plants and help stabilize their roots. Such wastes are also known as mushroom substrate (基质) and people often grow mushrooms in them.
May and Jiwon planted over 2,000 scallion (大葱) seeds in pots of soil. Half the seeds got soil polluted with micro-plastics. The rest grew in plastic-free soil. The plants then were further divided into four groups. The young scientists added AMF to the soil in one group. Another group had a top layer of mushroom substrate. A third group got both treatments. The last group got none. For three weeks, the pair tracked how many scallions sprouted (发芽) in each group and measured the plants’ height once each week.
About twice as many scallions sprouted in clean soil compared to that containing plastic bits. But among plants surviving in the polluted soil, a combination of AMF and mushroom substrate helped them out. Those getting both treatments grew 5.4 centimeters per week. That was faster than either of the treatments alone or those getting none.
Jiwon and May then looked at the plant roots with a microscope. Where AMF had been added, it grew into those roots. That increased the scallion roots’ surface area, May said, which should promote their uptake of nutrients. So “I see this project as coming up with a sustainable solution for plant growth in polluted soils,” said May.
1. Why did May and Jiwon work together?| A．To see the effects of long-lived plastics on farm crops. |
| B．To find the relationship between plants and fungi. |
| C．To design a research on the growth of plants. |
| D．To explore the way that the ecosystem works. |
| A．To prove the existence of micro-plastics. | B．To compare fungi with farm wastes. |
| C．To tell the advantages of farm wastes. | D．To provide some related information. |
| A．Its purpose. | B．Its design. | C．Its findings. | D．Its reasons. |
| A．By keeping the plants more resistant to pollution. | B．By allowing the plants’ deep area more freedom. |
| C．By making nutrients more available to the plants. | D．By exposing the roots to a larger surface area. |
2 . When I was a kid, a sycamore (枫树) grew in front of my home. At the age of 10, I was just tall enough to reach its lowest branch and lift myself into its embrace. Sometimes two or three of my friends would join me in the sycamore, or in the maple down the street, or Mrs. DiMarco’s old peach tree, some of whose stout horizontal branches allowed us to sit shoulder to shoulder, eating sweet fruit.
In my small town there are some kinds of trees, their branches spreading wide, open for business. But I have not yet seen a climber. Perhaps computer games have replaced tree climbing, or maybe the activity went the way of monkey bars, which came to be viewed as too risky and have largely disappeared from playgrounds.
It is a sad loss. I have always believed that, since low-hanging branches provide no benefit to the tree, they must be meant for the child. Robert Frost understood this when he wrote:
When I see baches (桦树) bend to left and right,
Across the lines of straighter darker trees,
I like to think some boy’s been swinging them.
My only disagreement with Frost is his inference that tree climbing is a gender-specific task. Both boys and girls make a joyful climb.
The campus of the university where I teach has all sorts of trees. During a recent walk, I found myself bending under the branch of an immense spruce (云杉). I grabbed the thing, and a moment later was sitting on a branch. Then the memories came flooding back. The old sycamore, the friends, and finally, the reluctance to return to earth when the parental call to supper came.
I was so lost in my thoughts that I didn’t hear the student calling to me from below. He asked what I was doing. I didn’t waste time on explanations. “Come on up,” I said “The air’s fine.” But he only laughed and waved me off. He didn’t know what he was missing.
1. What does the underlined word “stout” in Paragraph 1 probably mean?| A．Slim. | B．Bent. | C．Smooth. | D．Strong. |
| A．Why kids don’t climb trees. |
| B．Why monkey bars are dangerous. |
| C．Why there is no business under trees. |
| D．Why kids are addicted to computer games. |
| A．Some branches of trees are useless. |
| B．Trees are intended for kids to climb. |
| C．Trees are a source of inspiration for poets. |
| D．Climbing trees is a unique right of boys. |
| A．The explanations to his question. |
| B．The fresh air above the tree. |
| C．The pleasure of climbing trees. |
| D．The sense of safety on earth. |
3 . In ancient Greece, purslane herb (马齿苋) was regarded as an important medicinal herb for treatment of fever, female disorders, stomachaches, and headaches, and Hippoctrates, the famous father of medicine, practically tried it for the healing of wounds. Purslane herb was later considered as a cold herb around the 17th. Century.
Purslane is today known as a beneficial juicy herb found as a weed throughout the world. Purslane is commonly used as an ingredient for salads. Purslane has been recently identified as an excellent source of alpha-linolenic acid (亚麻酸). Alpha-linolenic is a kind of an omega-3 fatty acid, also known as fish oil. This important content in purslane herb plays an important role in human growth, development and preventing disease. Modern medical research claims that purslane herb is five times richer in omega-3 fatty acids than another vegetable, and also is high in vitamin C.
Purslane has small, green leaves, which are usually delicate and juicy. The stem is round and smooth. Young plants have a green stem but as the plant matures the stems take on reddish colors. Flowers are 1/4 inch long and a brilliant yellow in color with 5 petals (花瓣), which contain round black seeds. Purslane herb presents a wide variety of medical uses and each part of the herb is beneficial. Purslane herb is widely used all over the world and here is its known benefit: Purslane is known as an excellent source of vitamins C and E and the essential alpha-linolenic acids.
Reports describe purslane as power food of the future because of its high value of nutrition and medicine. Purslane leaves contain Omega-3 fatty acids which regulate the metabolic (新陈代谢) activities of bodies. The stems of purslane herb are known to be high in vitamin C. Purslane-herb is known to have one of the best known concentrations of Omega-3 fatty acid.
1. In ancient Greece, Hippoctrates used purslane to treat ________.| A．Stomachaches | B．Wounds | C．Headaches | D．Fever |
| A．Its stems are round and strong. |
| B．Its leaves are big and green. |
| C．Its stems are red in color. |
| D．Its flowers are yellow in color. |
| A．Because its leaves are rich in vitamin C. |
| B．Because its stem contains Omega-3 fatty acids. |
| C．Because it is valuable in nutrition and medicine. |
| D．Because it regulates the metabolic activities of bodies. |
| A．Purslane, a famous herb in the world |
| B．The basic knowledge about purslane |
| C．Purslane, a herb that benefits health |
| D．The medical research about purslane |
4 . The Greenwood fire took its name from the nearby lake where lightning struck on Aug.15, causing a wildfire that burned for weeks. Fueled by drought and wind, its persistence dominated headlines for much of late summer and early fall in Minnesota. When the last flames were finally put out, the northern Minnesota fire had consumed nearly 27,000 acres, countless firefighting resources, and at its worst, the lives that some had built around nearby McDougal Lake. Vast areas of forest were left burned-out, with the black and bare remains of what were once massive pines.
But, despite the destruction left behind, Mother Nature is set to a comeback. When organic matter is burned from the forest floor, seeds dropped by plants and trees begin to take hold, with the sprouting species emerging first. The trees above have died, which sends a chemical signal to the root system that is actually more expansive than just under that tree, and that chemical response encourages those root systems to re-grow. Ten years ago, a fire ripped through 93,000 acres of Minnesota forest in and around the BWCA. Today, that burnt area's rebirth is well underway.
"Here in the Pagami Creek wildfire scar, we have Jack Pine, Red Pine, Black Spruce, Aspen and paper birch-those are our main species, those are the ones that are growing quickly. It's 10 years on, and these trees are 10 to 15 feet tall in many areas," said Kyle Stover from the U.S. Forest Service.
A wildfire kills most things in its path, but despite the flames and intense temperatures, rarely is everything reduced to ashes -and that plays a key role in a forest's regeneration. Just one year after the fire, the survivors dominate the forest, and grasses replace the burnt ground. Wildflowers are abundant bushes and small trees have started to grow, and Jack Pine returned. So, it's an amazing ecological system of creating new forest life when it appears that all is lost, one that has evolved throughout the ages, where fire has always played a vital role.
1. What can we learn about the Greenwood fire?| A．It was a natural occurrence | B．It was caused by drought. |
| C．it gained half-year fame. | D．It took many people's lives. |
| A．Seeding growth is held up. | B．Burnt organic matter hardly functions. |
| C．Root systems spread further and wider | D．Chemicals in the soil are in greater demand. |
| A．They are flammable | B．They are fire-resistant |
| C．They are fire-adapted. | D．They are overgrown. |
| A．A fire. | B．A life | C．A time. | D．A system |
5 . Ever since humanity began to farm our own food, we've faced the unpredictable rain that is both friend and enemy. It comes and goes without much warning, and a field of leafy greens one year can dry up and blow away the next. Food security and fortunes depend on sufficient rain, and nowhere more so than in Africa, where 96% of farmland depends on rain instead of the irrigation common in more-developed places. It has consequences: South Africa's ongoing drought — the worst in three decades — will cost it at least a quarter of its corn harvest this year.
Biologist Jill Farrant of the University of Cap Town in South Africa says that nature has plenty of answers for people who want to grow crops in places with unpredictable rainfall. She is hard at work finding a way to take qualities from rare wild plants that are adapted to extreme dry weather and use them in food crops." The type of farming I am aiming for is literally so that people can survive as it's going to get drier and drier," Farrant says.
Extreme conditions produce extremely tough plants and a few fierce plants are highly adaptable to the everchanging conditions. Farrant calls one of them resurrection plants (复苏植物). During months without water under a harsh sun, they fade and contract until they look like a pile of dead green leaves but rainfall can revive them in the matter of hours. That is to say, when they detect and extend dry period, they produce sugars and certain stress-associated proteins and other materials in their tissues to enter a glass-like state that is “the most stable state that a plant can maintain”.
Last year, after Chinese team published a draft genome (基因组)of rock violet, one of the best studied resurrection plants, Farrant and colleagues published a detailed study of another candidate. One or both of these models will help researchers test their ideas-so far mostly done in the lab-on test plots.
1. Which can be responsible for the reduction in corn crop in South Africa?| A．Facing unpredictable rain. |
| B．Lacking advanced irrigation. |
| C．The food security. |
| D．The ongoing drought. |
| A．To maintain the most stable state of tough plants. |
| B．To grow crops in places with unpredictable rainfall. |
| C．To apply the special quality of wild plants to human farming. |
| D．To survive extreme dry weather and ever-changing conditions. |
| A．shrink | B．die | C．withdraw | D．rest |
| A．The research is still on trial. |
| B．Chinese team worked harder. |
| C．One of the candidates has been put into use. |
| D．The results contribute to resurrection plants. |
