Food from the air
Everyone has seen plants growing, but have you ever thought
First, he dried some soil, put it into a pot and weighed it. Next, he weighed a small tree, planted it in the pot and added rain water. Then, he watered it
After five years, he removed the tree from the pot and weighed it again. He found that the tree had gained
We now know that plants and trees make their own food. Their leaves, when exposed
| A．From not enough water. |
| B．From not enough sun. |
| C．From not enough plant food. |
Camellias (山茶花) are available in a great range
In the 1960s, Chinese scientists announced their discovery of the golden camellias. It was an
Unfortunately, in the past, golden camellias were cut down in large numbers because
Year after year, the Huang brothers spent much time working
4 . We are learning more and more every day about just how smart some animals are: monkeys, some species of birds, dogs, cats. But how about other animals? Snails? Mosquitos? They sure seem less smart. Still smarter than plants, though. Because it would be difficult to argue that plants are intelligent. Or would it?
In a new study, it was shown that plants send out sounds when they are sad. And these sounds are very different depending on whether they have recently been cut or whether they don’t have enough water. The sounds can’t be heard by human ears, as they are between 20 and 100 kilohertz, which is above the bottom of human hearing (which usually has the upper limit of 15-17 kilohertz).
These are fantastic results: plants don’t suffer in silence; they are screaming with pain. That is exactly what the popular science press has been doing.
There is no evidence that they are heard by anyone although theoretically (理论上) some animals — bats, moths, mice — could actually hear it as their ears are sensitive to the plant sounds. And it could very well be a byproduct (副产品) of the physical condition of these plants: less water in the system leads to more air bubbles (气泡) in plants, which leads to the sound of the popping of these bubbles.
Is this a disappointing explanation? I don’t think so. The aim is to understand why plants do what they do. And the results about the sounds contribute to this body of knowledge. They could even lead to better ways of controlling the needs of plants in gardening by sound observation.
All of this is true even if the plants don’t strictly “cry” or “scream”.
1. Why are we unable to hear the sounds of plants?| A．Because they are imagined by humans. |
| B．Because they go beyond human hearing. |
| C．Because plants don’t actually give off sounds. |
| D．Because plants are not as intelligent as animals. |
| A．Plants keep silent even when they suffer. |
| B．Water in the plants sends off different sounds. |
| C．The plant sounds might show their feelings or needs. |
| D．The study aims to control the needs and feelings of plants. |
| A．Because plants don’t actually “cry” or “scream”. |
| B．Because the results prove their knowledge of plants. |
| C．Because the results show that-plants understand what they do. |
| D．Because plants’ demands could be met by observing their sounds. |
| A．Plants suffer in silence | B．Plants “cry” in pain |
| C．Plants “scream” with joy | D．Plants need attention |
5 . A Fish and Wildlife Service proposal would protect the whitebark pine as an endangered species. Whitebark pines can live for up to 1,000 years and grow at elevations (海拔) as high as 12,000 feet. Environmentalists had requested the government in 1991 and again in 2008 to protect the trees. A nonnative fungus (真菌) has been killing whitebark pines for a century. More recently, the trees have proved vulnerable (易受伤的) to tiny insects that have killed large areas of forest.
The whitebark pines have almost disappeared in some areas, including the eastern edge of Yellowstone National Park, where they are a source of food for threatened grizzly bears (灰熊). This makes the government’s declaration of the Yellowstone area’s grizzly bears as a restored species a lie.
After being blamed for not taking steps to protect the trees, wildlife officials in 2011 admitted that whitebark pines needed protection, but they didn’t act rapidly, saying other species faced more immediate threats.
A lawyer for the Natural Resources Defense Council, which made the formal request for protection in 2008, expressed his disappointment that it took so long but said the proposal was still worth celebrating.
The government’s proposal described the threats to the trees as immediate and said the whitebark pines were one of many plants expected to be harmed as climate change moves faster than they can adapt. “Whitebark pines survive at high elevations already, so there is little remaining habitat in many areas for the species to move to higher elevations in response to warmer temperatures,” Fish and Wildlife Service officials wrote.
Government officials are working with researchers and private groups on plans to gather seed from trees, grow them in greenhouses and then plant them back on the landscape, according to Fish and Wildlife Service biologist Amy Nicholas. A proposal of that nationwide restoration is expected by the end of this year. “We do have options to restore this species,” Nicholas said.
1. What do we know about whitebark pines?| A．They are long-lived, high-elevation trees. |
| B．They have a strong resistance to nonnative fungi. |
| C．The government used to care about protecting them. |
| D．They and small insects depend on each other for survival. |
| A．Grizzly bears are no longer threatened. |
| B．The whitebark pines have almost disappeared. |
| C．The population of grizzly bears has increased greatly. |
| D．The government is actually doing nothing to protect bears. |
| A．Better late than never. | B．All roads lead to Rome. |
| C．Never do things by halves. | D．The first step is the hardest. |
| A．Irresponsible. | B．Doubtful. | C．Optimistic. | D．Uncertain. |
6 . Worldwide, there are more than a thousand mistletoe (槲寄生) species. They grow on every continent except Antarctica. They are parasites(寄生物) and live on the branches of their plant “hosts”, absorbing water and nutrients to survive. They accomplish this thievery via a specialized structure that infects their hosts. In fact, they infect plants of all kinds, including themselves—a number of species have been documented parasitizing other mistletoe species.
Yet despite their parasitism, mistletoe species may well be the Robin Hoods of plants.(Robin Hood is a character in old English stories who lives in a forest with a group of friends and steals money from rich people in order to give it to poor people.) They provide food, shelter and hunting grounds for other animals. Fallen mistletoe leaves release nutrients into the forest floor that would otherwise remain locked within trees, and this generosity benefits the food chain. “Yes, ecologically, they are cheats,” says David Watson, a community ecologist at Charles Sturt University at Albury-Wodonga, Australia. But they share their wealth. “They steal these nutrients, and then they drop them,” Watson says.
Mistletoe species depend critically on animals to get around. Most mistletoe fruits are berries containing a single seed that’s surrounded by a sticky layer. Roughly 90 bird species are known to consume mistletoe species’ seeds, so the birds can pass them to other trees on their bodies, or when they are eaten, seeds are passed through their waste. (There are exceptions: Some mistletoe species make explosive fruits that send their seeds toward nearby trees, reaching distances of 10 meters or more.)
Scientists have known that mistletoe species all have ancestors that were parasites not on branches, but on roots. “They evolved over and over and over, and this understory, root-parasitic, shrubby thing switched to being an aerial(meaning they infect above-ground plant parts, rather than roots), parasitic shrubby thing,” Watson says. Moving up the tree helped to solve a problem that all plants are faced with: competing for sunlight. Despite their parasitic nature, most mistletoe species still use energy from light to make their food.
1. What can we learn about mistletoe species according to paragraph 1?| A．They are highly independent. | B．They are harmful to their hosts. |
| C．They can be found on every continent. | D．They prefer to live on the roots of plants. |
| A．They help poorly grown trees absorb more nutrients. |
| B．They have remarkable abilities to survive in the forest. |
| C．They live in the forest with other plant species in groups. |
| D．They steal and give food to many other living things. |
| A．With the help of birds. | B．By making explosive fruits. |
| C．With the help of nearby trees. | D．By taking advantage of hosts’ seeds. |
| A．They eventually evolved into shrubby plants. |
| B．Their habitats changed from roots to branches. |
| C．They tried to give up using energy from sunlight. |
| D．Their parasitic nature was formed in a gradual way. |
7 . After tracking flowers on a prairie (草原) in Minnesota for 21 years, scientists reported that the plants reproduce more successfully in the year following a carefully controlled burn. Understanding the relationship between prairie plants and fire is important for preserving this ecosystem which is becoming rapidly smaller, says Stuart Wagenius, a conservation scientist.
Fire provides an additional advantage for the narrow-leaved purple coneflower (紫锥花), as Wagenius and his colleagues say. To really bloom (开花), they need a little help: Enter the fire. Between 1996 and 2016, Wagenius says his team tracked nearly 8,000 purple coneflowers on the Staffanson Prairie Preserve. In 9 of those years, they conducted controlled burns over 400 times. “In the summer after a burn, many more plants flower,” Wagenius says. “It is just a huge flowering festival.”
Purple coneflowers and many other prairie plants were previously known to bloom energetically after fires. However, the researchers said that fire also stimulated purple coneflowers to bloom at the same time in the summer after a burn. This meant that instead of being unconnected, the purple coneflowers were surrounded by potential mates and went on to produce nearly double the number of seeds compared with other years. Wagenius says it’s not yet clear exactly how fires signal the flowers to get busy.
The new findings may help the people who manage prairies to better understand the different ways that fire affects the plants growing in these habitats, said Kathryn Yurkonis, a grassland ecologist who was not involved in the research. However, Yurkonis added, it remains to be shown how the fires influence the purple coneflower population. “This paper implies that making more seeds would mean more seeds would land on the soil and enter the population of plants — but they don’t actually examine that step,” she said. “I’d be curious to see whether this actually translates to more purple coneflowers.”
1. What is the basis for the research?| A．Prairies are easy to disappear. | B．Plants on a prairie are diverse. |
| C．Fire relates positively to prairie plants. | D．Without fire, flowers won’t bloom. |
| A．Wagenius’s team was committed indeed. |
| B．Samples of flowers were rich in number. |
| C．Time spent on the research was long. |
| D．The findings were relatively convincing. |
| A．The result of plants being unconnected. |
| B．The influence of fires on prairie plants. |
| C．The process of prairie plants’ growing after fires. |
| D．The reason for plants’ blooming at the same time. |
| A．Uninterested. | B．Prejudiced. | C．Objective. | D．Opposed. |
8 . More than half the world relies on rice as a main food source. Yet the crop faces an worrying future as global warming increases the Earth’s temperature and adds to more storms, droughts and heat waves, because rice is sensitive (敏感的) to climate extremes and grows in places already experiencing many. Any disturbance to that food source can cause great problems.
The latest report from the Intergovernmental Panel on Climate Change—which brought together 234 scientists to collect recent climate studies—warned that human-caused global warming is happening at an extraordinary pace and is adding to the deadly floods, heat and droughts that we’re already witnessing. And those events result in major risks to farming.
“Higher temperatures lead to increased water loss, resulting in soil drying, increased plant stress and impacts on agriculture, especially in regions where large amounts of rainfall are not expected,” the report states.
If greenhouse gases are not reduced, about a third of global land areas are expected to suffer from at least moderate drought by the end of the century, the report concludes. Some changes like sea-level rise are already locked in.
Rice is especially sensitive to these changes. Rice often grows in ecosystems, such as deltas (三角洲), that have low sea-level and are easy to be influenced by rising seas. Any additional temperature increase could cause sea water into the filed where a healthy crop can develop, scientists say.
A 2018 study in the Archives of Agronomy and Soil Science found that an increase in the frequency and seriousness of hot weather could reduce rice outputs by up to 40% by the end of this century.
“Most of the world’s rice is currently grown in regions where existing temperature is already close to the most suitable range for rice production,” the study states. “Therefore, any further rise in temperature or short period of high temperature during sensitive growth stages will be disastrous.”
1. Why is rice particularly weak to climate change according to the passage?| A．Rice requires large amounts of rainfall. |
| B．Rice is grown in regions with low sea levels. |
| C．Rice is hard to live in places with extreme climate conditions. |
| D．Rice is grown in regions with high levels of greenhouse gases. |
| A．Rising sea levels |
| B．Increased frequency of storms |
| C．Global warming and climate change |
| D．Reduction in greenhouse gas emissions |
| A．Pessimistic | B．Optimistic | C．Uncertain | D．Encouraging |
| A．Rice Output Is Decreasing Heavily. |
| B．Climate Change is Caused by Greenhouse Gas. |
| C．Climate Change Resuits in Low Output of Rice. |
| D．Greenhouse Gas Has Great Effect on Rice Growing. |
9 . House Plants That Are Easy to Grow
Jessica Damiano is an expert at taking care of plants. She writes stories about how to keep plants in good condition.
As a result, Damiano chooses house plants that need the least amount of care for her home.
Chinese evergreen is a beautiful house plant that does well in low-light conditions. Damiano said all you need to do is keep the plant’s soil lightly wet at all times and fertilize (施肥) every other month over the winter and every month for the rest of the year.
The cast iron plant is as strong as its name sounds. Damiano said it does not even want your attention.
One house plant, the aloe plant, can be used for treating burns.
Similar plants called succulents share aloe plants’ ability to store water within their leaves.
| A．Avoid providing too much sunlight. |
| B．But even she has killed house plants. |
| C．These house plants usually need much attention. |
| D．She looks for plants that grow well with very little water. |
| E．There are many other house plants that need little water and sunlight. |
| F．These sorts of plants usually do well where conditions are dry and warm. |
| G．When necessary, just cut open a leaf and use the juice from within on an injury. |
10 . This is the time of year when many gardeners are harvesting tomatoes. Gardening expert Jessica Damiano recently reported about the many pictures of strangely shaped tomatoes sent to her from fans of her gardening advice.
Not every tomato on an affected plant will be deformed (改变形状), however. What are the possibilities? Under the right conditions (temperatures that are too hot or even too cold), this could affect one or two tomatoes per plant, depending on where they are in the development process and what the (weather) conditions are, said Timothy McDermott, a professor at Ohio State University. The possibility of one of your tomatoes developing a locule oddity (怪异) is about one in a thousand, McDermott said.
And, when harvesting your crop, remember:
| A．select the good-looking ones. |
| B．Any tomato can grow an extra locule. |
| C．the funny-looking tomatoes taste just as good! |
| D．What causes the unusual appearance of tomatoes? |
| E．Unless otherwise diseased, they are perfectly good for eating. |
| F．She said people sometimes question if the tomatoes are okay to eat. |
| G．Provide shade for your plants when temperatures are predicted to remain above 32℃. |
