1 . 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.

2 . When gardeners grow varieties of plants in their beautiful gardens, they are happy to see beneficial insects like bees and butterflies surrounding the flowers. But as they take a closer look, they may find some plants are covered in black dots and filled with harmful insects or pests. Some gardeners may immediately reach for chemicals.     1     Although it may stop the insect problem, it will also threaten bees and butterflies which help the plants reproduce.

If you are wise gardeners, you should first take preventive measures to control the harmful insects.     2     Only when there are too many harmful insects, should pest control be considered. The first defense should always be the safest method available.

Prevention

As a rule, prevention is the best treatment. Inspect plants closely, including their leaves, before buying them from the store.     3    

When planting, space plants out to permit them to grow to their full size. Plants too close together can breed harmful organisms, like bacteria.

    4     They invite pests if permitted to remain on the ground. When you do see pests, wash them away. Use rubbing alcohol to remove some insects, or pick them off the plants.

Pesticides

If you decide a pesticide is necessary, choose it carefully and follow the directions and warnings on the product. Avoid using pesticides in extreme heat, on windy days, or when the plants are wet.     5     At the time, beneficial insects are inactive. You can consider removing flowers from the plants to lessen the risk that beneficial insects will come in contact with the pesticides.

A．But this is not wise.

B．In most cases, chemicals don’t help.

C．Treat the plants early in the morning or at night.

D．Also do remember the plants need nutrition and care.

E．Keep your garden free of fallen leaves, fruits and other wastes.

F．Do not bring any plants home that show signs of disease or pests.

G．The process starts with the idea that having some pests is acceptable.

3 . Indoor plants might look as if they just sit around not doing much, but in many ways they are the unsung heroes of the home.     1    , but studies have shown that they can promote people’s wellbeing by improving their mood (心情), reducing stress and helping their memory. What’s more, indoor plants are easy to look after and are not very expensive.

What are indoor plants?

Indoor plants, also known as houseplants or pot plants, are plants that like to grow indoors. Many of these species (物种) are not ideally suited to growing outside in the UK, especially in the winter.     2    .

Why are indoor plants good for you?

Will Spoelstra, who works at the Royal Botanic Gardens, says, “    3    . I find during the winter months, plants around the house can really lift your mood.” Several studies have backed this up and found that indoor plants can improve creativity, focus and memory. There is also research showing that pot plants can clean the air around them by removing harmful gases, such as carbon dioxide. They also remove some harmful chemicals from paints or cooking.     4    .

Which plants can you grow?

Aloe vera, peace lilies and spider plants are some of the species that are easy to grow indoors. You can buy plants from supermarkets, garden centres or online. Younger plants are often cheaper than fully grown ones, and you get to care for them as they mature — which is part of the joy of owning plants. “    5    ,” Spoelstra says. “It can bring a new interest and focus into people’s lives and help to make the link between home and nature.”

A．All plants are different

B．Not only do they look beautiful

C．There are many benefits to growing plants indoors

D．Instead, they grow better inside, where it is warmer

E．Plants like peace lilies and devil’s ivy are among the best

F．Changing the pot of your plant from time to time will also help

G．Learning about the requirements of each plant can be very rewarding

4 . 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.

5 . For many people, catching a smell of freshly cut grass is a pleasant sign that warmer weather is here to stay. For the grass, however, this scent signals an entirely different story.

The smell we associate with freshly cut grass is actually a chemical SOS, one used by plants to beg nearby creatures to save them from attack. After all, when danger strikes —whether it's gardening equipment or a hungry caterpillar — plants can't lift their roots and run. They must fight where they stand. To protect themselves, plants employ a string of molecular (分子) responses. These chemical communications can be used to poison an enemy, warn surrounding plants of dangers or attract helpful insects to perform needed services.

Clearly, plants can communicate. But does that mean they can feel pain? According to some researchers, plants release gases that are the equivalent of crying out in pain. Using a laser-powered microphone, researchers have picked up sound waves produced by plants releasing gases when cut or injured. Although not audible to the human ear, the secret voices of plants have revealed that cucumbers scream when they are sick, and flowers cry when their leaves are cut.

There's also evidence that plants can hear themselves being eaten. Researches show that plants understand and respond to chewing sounds made by caterpillars dining on them. As soon as the plants hear the noises, they respond with several defense mechanisms.

For some researchers, evidence of these complex communication systems — giving out noises via gas when in pain — signals that plants feel pain. Others argue that there cannot be pain without a brain to register the feeling. Still more scientists infer that plants can exhibit intelligent behavior without possessing a brain or conscious awareness.

As they grow, plants can change their paths to avoid obstacles or reach for support with their tendrils (卷须). This activity comes from a complex biological network distributed through the plants' roots, leaves and stems. This network helps plants reproduce, grow and survive.

1. What does the smell of freshly cut grass signal?

A．Warmer weather.	B．Being poisonous.
C．Cry for help.	D．The need of services.

2. How do plants convey their pain?

A．By giving out gases.	B．By changing the color of their leaves.
C．By producing audible sound waves.	D．By sharing it through the root systems.

3. What makes plants' intelligent behavior possible?

A．Their tendrils.	B．Their biological network.
C．Their communication systems.	D．Their conscious awareness.

4. What is the best title for the text?

A．Do plants feel pain?	B．How plants protect themselves?
C．Do plants communicate?	D．How plants grow and reproduce?