1 . Common water plant could provide a green energy source. Scientists have figured out how to get large amounts of oil from duckweed, one of nature’s fastest-growing water plants. Transferring such plant oil into biodiesel (生物柴油) for transportation and heating could be a big part of a more sustainable future.
For a new study, researchers genetically engineered duckweed plants to produce seven times more oil per acre than soybeans. John Shanklin, a biochemist says further research could double the engineered duckweed’s oil output in the next few years.
Unlike fossil fuels, which form underground, biofuels can be refreshed faster than they are used. Fuels made from new and used vegetable oils, animal fat and seaweed can have a lower carbon footprint than fossil fuels do, but there has been a recent negative view against them. This is partly because so many crops now go into energy production rather than food; biofuels take up more than 100 million acres of the world’s agricultural land.
Duckweed, common on every continent but Antarctica, is among the world’s most productive plants, and the researchers suggest it could be a game-changing renewable energy source for three key reasons. First, it grows readily in water, so it wouldn’t compete with food crops for agricultural land. Second, duckweed can grow fast in agricultural pollution released into the water. Third, Shanklin and his team found a way to avoid a major biotechnological barrier: For the new study, Shanklin says, the researchers added an oil-producing gene, “turning it on like a light switch”by introducing a particular molecule (分子) only when the plant had finished growing. Shanklin says, “If it replicates (复制) in other species-and there’s no reason to think that it would not — this can solve one of our biggest issues, which is how we can make more oil in more plants without negatively affecting growth.”
To expand production to industrial levels, scientists will need to design and produce large-scale bases for growing engineered plants and obtaining oil — a challenge, Shanklin says, because duckweed is a non-mainstream crop without much existing infrastructure (基础设施).
1. What can people get from duckweed firsthand?| A．Plant oil. | B．Stable biodiesel. |
| C．Sustainable water. | D．Natural heat. |
| A．Options for renewable energy. |
| B．Reasons for engineering genes. |
| C．The potential of revolutionary energy source. |
| D．The approach to avoiding agricultural pollution. |
| A．Industrial levels. | B．Unique design. |
| C．Academic research. | D．Basic facilities. |
| A．Duckweed Power | B．Duckweed Production |
| C．Genetic Engineering | D．Genetic Testing |
2 . On the streets of Manhattan and Washington, D. C., in neighborhoods in Seoul and parks in Paris, ginkgo (银杏) trees are losing their leaves in reaction to the first gust of cold winter air. This leaf drop, gradual at first, and then sudden, carpets streets with golden, fan-shaped leaves. Scientists are documenting evidence of the event happening later and later, a possible indication of climate change. But the story of ginkgos is not the familiar one of human carelessness with nature.
Thanks to fossils found in North Dakota, scientists found a ginkgo has genetically similar ancestors dating back 170 million years to the Jurassic Period. “It almost went extinct. Then humans rescued it and spread it around the world. It’s such a great evolutionary (进化) and cultural story,” says Peter Crane, a ginkgo expert.
One theory for the decline of the ginkgo species began 130 million years ago, when flowering plants began spreading. They grew faster and attracted more pollinators (传粉者) than ginkgos. “It’s possible that ginkgos were elbowed out of the way,” says Crane. Already competing to survive, ginkgos began to disappear during a time of global cooling that began around 66 million years ago. By the time the last ice age ended 11,000 years ago, the remaining survivors were found in China.
Ginkgo trees are smelly. “My guess is that they were eaten by animals that liked smelly things. They then passed through their body and grew.” Crane says. Those same seeds may have helped ginkgo find favor with humans 1,000 years ago. Once cleaned of their outer layer, ginkgo seeds are safe to eat. It’s then, when the trees had long since disappeared elsewhere, that people in China may have begun planting them and eating their seeds. Then gradually ginkgos spread across the world. Now it’s seemingly naturally resistant to insects and high levels of air pollution.
Crane isn’t worried about its future, though: The popularity of the species will help it survive. “Though its status in the wild may be difficult to access, it’s a plant that’s unlikely to ever go extinct,” he says.
1. What may have caused the further delay of ginkgo’s leaf drop?| A．The colder weather in winter. |
| B．The protection from city councils. |
| C．The global warming phenomenon. |
| D．The careless interaction with humans. |
| A．The reasons why ginkgos almost died out. |
| B．The advantages of ginkgos over other plants. |
| C．The theories of experts for multiplying ginkgos. |
| D．The competition between various flowering plants. |
| A．Their eatable seeds. | B．Their unpleasant smell. |
| C．The natural evolution. | D．The careful planting. |
| A．Worried. | B．Optimistic. | C．Uncertain. | D．Hopeless. |
3 . Scientists have shown how plants can protect themselves against genetic (基因的) damage caused by environmental stresses. The growing tips of plant roots and shoots have an in-built mechanism (机制) that spells cell death if DNA damage is detected, avoiding passing on faulty DNA.
Plants have small populations of stem cells (干细胞) at the tips of their roots and shoots, which enable them to continuously grow and produce new tissues throughout their lifetime. These stem cells serve as ancestors for plant tissues and organs. However, any genetic faults present in the stem cells will continue to exist and be passed on permanently throughout the plant’s life, which could last thousands of years.
Given the critical role of stem cells and their exposure to potentially dangerous environments at the growing tips of roots and shoots, safeguards are necessary to prevent stem cell faults from becoming fixed. Researchers Nick Fulcher and Robert Sablowski, funded by the Biotechnology and Biological Sciences Research Council, aimed to uncover these protective mechanisms. Through experiments involving X-rays and chemicals, they discovered that stem cells were more sensitive to DNA damage compared to other cells.
When DNA damage occurs, the cells have the capacity to detect it and cause programmed cells to die, preventing the propagation of the damaged genetic code to the rest of the plant tissues. This process has similarities to the safeguard mechanism found in animal cells, which has been broadly studied due to its relevance in preventing cancer.
The identification of a similar protective system in plants is of great interest in the field of plant development. It also helps scientists develop plants that can better handle environmental stress. So knowledge of how plants deal with these stresses is of fundamental significance to agricultural science’s response to climate change.
1. What is the function of the in-built mechanism in plants?| A．To produce more roots and shoots. | B．To increase the overall lifetime of the plant. |
| C．To enhance plant growth and nutrient intake. | D．To stop genetic faults in stem cells passing on. |
| A．They are relatively abundant in quantity. | B．They are resistant to environmental stresses. |
| C．They make quick response to DNA damage. | D．They have the ability to repair damaged DNA. |
| A．Spread. | B．Change. | C．Existence. | D．Self-repair. |
| A．The way of dealing with climate change on the earth. |
| B．The significance of identifying the protective system in plants. |
| C．The method of ensuring plant survival under environmental stress. |
| D．The urgency of developing plants that can handle environmental stress. |
4 . Imagine you are on a beautiful tropical beach. The blue water shines in the sun, and the sand is warm under your feet. You notice a small fruit in the sand. It looks like a little green apple. You pick it up and smell it... it smells sweet. But whatever you do. Don’t take a bite!
This is the fruit of the manchineel tree. It is the most poisonous tree in America. You can find it in Florida, as well as in the Caribbean, Mexico, and Central America.
If you were to eat the fruit, it would taste delicious. But then your mouth would start to burn. Your throat would tighten and make it difficult to breathe. You could even die.
The fruit isn’t the only risky part of the manchineel tree. The tree is full of milky white sap. Sap is a liquid that flows through a plant, like blood flows through a person. The manchineel’s sap is hazardous. If it gets on your skin, it will cause painful blisters. So don’t try to cut down these trees, because you could get sap all over you!
And if you try to burn manchineel wood, the smoke will choke and blind you.
Manchineel trees are dangerous, but they’re also an important part of the environments where they grow. Manchineels protect beaches with their strong roots. The roots help stop sand and soil from washing away. This is good for the plants, animals, and people living nearby. There aren’t many manchineel trees left in the world. So even though they’re harmful, people are trying to protect them. Still, if you see one, stay away!
1. What do we know about the manchineel tree?| A．It looks ugly. | B．Its fruit is dangerous. |
| C．Its fruit tastes terrible. | D．It grows in cool places. |
| A．Clear. | B．Smelly. |
| C．Sweet. | D．Unsafe. |
| A．To help people choose fruit. |
| B．To introduce the manchincel tree. |
| C．To improve people’s sense of safety. |
| D．To attract people to tropical beaches. |
5 . When scientists talk about recent extinctions, birds and mammals (哺乳动物) get most of the attention. But the first global analysis of its kind finds it is twice as many plants that have disappeared as birds, mammals, and amphibians (两栖动物) combined.
Researchers reviewed published research, international databases, and museum specimens such as grasses from Madagascar, finding that 571 plants species have gone extinct in the past 250 years. One reason why the total is higher than that of the well-studied animals is that there are simply more species of plants. Looking at percentages, the situation is worse for mammals and birds. An estimated 5% of those species have gone extinct, compared with 0.2% of plants.
The loss includes the Chile sandalwood tree in the South Pacific, which was cut down for its fragrant (芳香的) wood. It was last seen on Robinson Crusoe Island in 1908. The extinction rates among plants have been highest for trees and shrubs on islands, which often have species that occur nowhere else, and in regions with rich diversity, especially the tropics and in Mediterranean climates.
Just a few years later, the world lost the banded Trinity (Thismia americana), a leafless plant that grew entirely underground except for its flowers. Most species of this kind of plant grow in rainforests, but this plant was first described in 1912 in a sandy wetland in Chicago, Illinois, and was wiped out by development.
According to the team’s report in Nature Ecology & Evolution, the total of 571 extinct plant species is four times higher than the official listing kept by the International Union for Conservation of Nature. Even so, it is probably still an underestimate (低估), as less is known about the status of plants in Africa and South America than on other continents. Many of these species may disappear, too. A major review of the status of global biodiversity recently estimated that more than a million species, including 14% of plant and animal diversity, are threatened with extinction.
1. What caused the extinction of the Chile sandalwood tree?| A．Climate change. | B．The market demand. |
| C．Environmental pollution. | D．The decline of the habitat. |
| A．It flowered without bearing seeds. |
| B．It disappeared during the 19th century. |
| C．It was a flowering plant without leaves. |
| D．It was a rare plant growing underground. |
| A．Their current situation is more worrying. |
| B．About one plant species dies out every year. |
| C．More plant species will keep alive in the reserve. |
| D．They would be replaced by other new species soon. |
| A．Sports. | B．Nature. | C．Entertainment. | D．Figures. |
6 . Dandelion (蒲公英)seeds are some of the best flyers in nature, catching the wind and spreading as far as 100 kilometers. Each dandelion seed is tied by a thin tube to around 100hairs, which form the parachute-like (类似降落伞的) structure, When seeds break free from the flower head, these hairs catch the wind and carry their seeds. This hairy parachute closes when the air is humid (潮湿的), which often means the wind is weak. In drier, windier conditions. dandelions widen their parachutes to better catch the wind so the seeds can fly freely.
However, in the past, nobody knew how they sense and respond to their environment so effectively.
Now researchers have uncovered the secret “thinking” behind dandelions’ spreading seeds. Their work. published in Nature Communications, found the seed-carrying parachutes open and close using something like actuators-devices that change signals into movement-without using active input of energy. The center of the parachutes senses the humidity of their immediate environment by absorbing water molecules (分子)from the air. Responding to these humidity signals. they either open their parachutes and fly away, or close their parachutes and stay put.
Study author Dr. Naomi Nakayama of the Department of Bioengineering who led the work said that their “findings reveal how the dandelion ensures the survival of its species by making perhaps the most important decision in a plant’s life—to stay or go seek a better habitat”.
“Understanding how dandelions work is fascinating because the dandelion is the foundation of ecosystems. It feeds insects and birds.” Nakayama says “So, the environmental sensitivity of their flight is an important topic for us to understand how nature will change in future climates.”
1. What can be learned from paragraph 1?| A．Dandelion seeds have a tube-like design. |
| B．A dandelion flower consists of 100 hairs. |
| C．Dandelion seeds begin to grow in dry weather. |
| D．The dandelion parachute closes on wet mornings. |
| A．Its hairs catch the wind easily. |
| B．Its actuator needs extra energy to function. |
| C．The middle of its parachute measures humidity. |
| D．Its actuator’s shape was changed by the wind. |
| A．To feed more insects and birds. | B．To better learn about climate change. |
| C．To explain their role in ecosystems. | D．To change dandelions’living environment. |
| A．Why dandelion seeds “prefer” the wind |
| B．How dandelions “tell” us their destinations |
| C．How dandelions “decide” to spread their seeds |
| D．Why dandelion seeds “create” parachute-like structure |
1. What makes potted roses easier to plant?
| A．Lower nutrition requirement. |
| B．Stronger cold resistance. |
| C．Better root development. |
| A．They need less soil. |
| B．They are easier to transport. |
| C．Their planting time is fixed. |
| A．Damp condition. | B．Heavy sunshine. | C．Continuous watering. |
| A．Types of roses. | B．Ways of rose packing. | C．Tips on rose growing. |
Housed in a small container and measuring just 0.5cm long, the weevil (象鼻虫) doesn’t look very
The weevil I saw in
The weevils were first used in the wild in the UK last winter. Now more will
9 . Growing plants is often seen as a very “green” thing to do, but like many products, they take a huge amount of energy to produce.
Over-consumption of plants is a big issue. It’s so easy to get overexcited when you see all these incredible plants, and you can end up carrying home huge numbers of them.
If you are ready and able to increase your collection, propagate(繁殖) from your own plants rather than buying more, and share plants with others.
Recycling takes a huge amount of input, which can end up more damaging to the environment, so instead of buying something of lower quality that needs replacing every year, buy fewer things of a higher quality.
| A．But large collections call for an enormous amount of work. |
| B．Many commercial growers continue to market their produce. |
| C．This removes the need to buy plants and encourages a sharing culture. |
| D．These will last many years and be more cost-effective in the long term. |
| E．So it’s important to assess your collection and buy plants you have time to look after. |
| F．Throwing them away will greatly reduce your gardening footprint on the environment. |
| G．Many large-scale growers have used technology to minimize their impact on the environment. |
10 . A major benefit of growing your own tomatoes is variety. If you visit a garden center, you will find seeds and small starter plants for yellow tomatoes, purple tomatoes, huge tomatoes, and even very small tomatoes.
Tomatoes grow best in soil with a pH level between 6.0 and 6.8. If the pH reading is lower than 6.0, you can add about 2 cups of dolomitic lime (石灰) into the soil for each plant.
If you want to grow really big tomatoes, try following these seven tips from expert growers: Select tomato seeds with names like Big Zac or Bull’s Heart.
Start seeds early indoors and re-plant them into larger containers several times before moving them outdoors.
Remove new flowers that develop at the top of the plant when older fruits near the bottom begin to grow.
Remove the small growths where the plant’s stems and branches meet. This will prevent them from taking away nutrients and shading developing fruit under them.
Finally, water, fertilize and weed!
| A．Plant them deep each time |
| B．Rich soil benefits the growth |
| C．Tomatoes are not difficult to grow |
| D．Skills are demanding in growing tomatoes |
| E．Cut back the plants to keep only one main branch |
| F．They are all genetically designed to produce large fruit |
| G．This will force the plant to produce fewer but larger tomatoes |
