1 . What foods do you use to celebrate with your family? Do you eat something special on your birthday or holidays? Among the Hopi people, many foods for special celebrations are made from corn.

The Hopi people are Native Americans who live in Black Mesa, Arizona, USA. They grow special types of corn with long roots (根), which help the corn reach water in the ground in the hot and dry desert (沙漠).     1     In fact, in Hopi tradition, corn is the first solid food a baby eats.

The Hopi use each color of corn for something different. For example, blue corn is used to make some traditional Hopi foods. Piki is one Hopi food made with blue com. It is like a paper-thin, rolled pancake.     2     When a new baby is born, cobs (玉米棒子) of white corn are placed in the baby’s cradle (摇篮).     3     When girls grow up, they grind (磨碎) com for four days as part of their Coming of Age Ceremony. The Hopi also grind com by hand for wedding ceremonies.

    4     For example, in some Hopi villages, women walk down the Mesa to gather water and firewood every day. Men in those villages run up to 40 miles to their farms every day to grow corn, bean, and chili pepper crops. Other Hopi live in modern homes and use modern technology in their daily lives.     5     Corn is an important part of Hopi life today.

A．The Hopi people have a long history.

B．Corn is also used in Hopi ceremonies.

C．There are different types of corn as well.

D．Corn plays an important role in the Hopi diet.

E．Some Hopi today still live as they did hundreds of years ago.

F．White corn is used to wish a baby good health and long life.

G．But both groups still practice Hopi spirituality and other traditions.

2 . 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.

2. What does paragraph 4 mainly convey?

A．Options for renewable energy.

B．Reasons for engineering genes.

C．The potential of revolutionary energy source.

D．The approach to avoiding agricultural pollution.

3. What is the decisive factor to mass-produce the plant?

A．Industrial levels.	B．Unique design.
C．Academic research.	D．Basic facilities.

4. What would be the best title for the text?

A．Duckweed Power	B．Duckweed Production
C．Genetic Engineering	D．Genetic Testing

3 . 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.

2. What does paragraph 3 mainly talk about?

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.

3. What might have contributed to ginkgos’ survival?

A．Their eatable seeds.	B．Their unpleasant smell.
C．The natural evolution.	D．The careful planting.

4. How does Crane feel about ginkgos’ future?

A．Worried.

B．Optimistic.

C．Uncertain.

D．Hopeless.

4 . 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.

2. What can we know about stem cells in plants according to the text?

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.

3. What does the underlined word “propagation” in paragraph 4 mean?

A．Spread.

B．Change.

C．Existence.

D．Self-repair.

4. What does the last paragraph focus on?

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.

5 . 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.    1    For example, they use geothermal(地热的) energy to heat greenhouses and solar power to supply electricity and lighting. While domestic growing doesn’t involve the same carbon footprint as commercial growing, it’s important to consider what we can all do to minimize our own impact while still enjoying growing plants.

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.    2     The more plants you have, the more limited your time and resources become, and plants can suffer. This leads to another issue-many people may end up throwing away their plants which don’t look perfect or stop flowering, in a similar way to the world of fast fashion.     3    .

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.     4    Meanwhile, we can build a community of like-minded, passionate plant people.

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.     5    And they can be passed down the generations.

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.