Extreme conditions produce extremely tough plants. The big difference between "drought—tolerant" plants and these tough plants: metabolism. Many different kinds of plants have developed tactics to weather dry spells. Some plants     1     of water to see them through a drought; others send roots deep down to subsurface water supplies. But once these plants use up their stored water or tap out the underground supply, they cease growing and start to die. They may be able to handle a drought of some length, and many people use the term "drought tolerant" to describe such plants, but they never actually stop needing to     2     water, so Farrant prefers to call them drought     3    .

Resurrection plants, defined as those capable of recovering from holding less than 0.1 grams of water per gram of dry mass, are different. They lack water—storing structures, and their existence on rock faces prevents them from     4     groundwater, so they instead developed the ability to change their metabolism. When they detect a/an       5     dry period, they change their metabolisms, producing sugars and certain stress—     6     proteins and other materials in their tissues. As the plant dries, these resources take on first the     7     of honey, then rubber, and finally enter a glass—like state that is "the most stable state that the plant can maintain," Farrant says. That     8     the plant's metabolism and protects its dried—out tissues. The plants also change shape, shrinking to minimize the surface area through which their remaining water might evaporate. They can recover from months and years without water, depending on the species.

What else can do this dry—out—and—revive trick? Seeds—almost all of them. At the start of her career, Farrant studied seeds such as avocados(牛油果) , coffee and lychee(荔枝). Though     9    , such seeds are delicate — they cannot bud and grow if they dry out. Most seeds can wait out the dry, unwelcoming seasons until conditions are right and they sprout. Yet once they start growing, such plants seem not to retain the ability to hit the     10     button on metabolism in their stems or leaves.

Climate change has already affected South America

Scientists have long warned that extreme weather would cause major disasters in the future. But in South America, that future is already here.

In the past month, there have been     1    landslides in Brazil, wildfires in Argentine wetlands and flooding in the Amazon. In just three hours on 15 February, the Brazilian city of Petropolis received over 25 centimetres of rainfall. That is the most recorded in a single day since officials began keeping records in 1932. The     2    landslides killed more than 200 people and left nearly 1,000 homeless.

A recent report by the Intergovernmental Panel on Climate Change(IPCC)has found that global warming is changing the strength and     3    of extreme weather events. These events have also become less     4    , the report said, leading to additional damage.

Recently, 70% of the city of Jordao in Brazil’s Amazon rainforest was underwater because of     5    from two rivers. The floods have severely affected the lives of thousands of people in the area, including in 32 indigenous communities.

The entire Amazon rainforest     6    between 150 and 200 billion tonnes of carbon in its plants and soil, says Carlos Nobre, a climate scientist. Nobre told The Associated Press, “If you lose the forest, this carbon dioxide… goes into the atmosphere. It is very important to     7    the forest.”

But most governments across the area have failed to consider the IPCC’s warnings and stop the destruction. In Colombia, a recent increase in forest fires led more than 150 international researchers and activists to send a letter urging the government to do more to prevent them. Local prosecutors and police officials have said the area is more and more dependent on activists for     8    

Alejandra Boloqui     9    a private protected land area in Argentina’s Ibera Wetlands. She has been helping firefighters fight against wildfires there. Recently, she recorded 12 alligators fleeing the fires and walking down a dirt road in search of water.

The alligators and many other animals found     10    in a nearby body of water that had dried up due to lack of rain. It has since been refilled using water pumps powered by the sun.

There is no doubt that human activities have warmed the atmosphere, oceans and land. To improve the situation, what can we do? Here are some tips on how to help protect our planet.

The first and most important thing you can do is keep talking about climate change to everyone. The greatest challenge in the history of our     1     should not be a taboo (禁忌) subject. Just one idea shared with one of your friends or relatives can     2     in protecting our planet.

As consumers, let’s try to make better choices. Think about these questions before you buy something. Can I reject all that packaging? Do I really need the new product? Besides, use     3     bottles and throwaway coffee cups less. You should keep refillable and     4     alternatives to hand. In addition, fix things when they are broken.     5    , you can replace your smartphone’s battery or screen instead of buying a whole new device.

If you use cars less, there will be less harmful     6     sent out to the environment. At the same time, there will be fewer     7    . You can get to your destination by walking, cycling or using public transport. If you need a car occasionally, hire an electric one. If you really need your own set of wheels, choose the most environmentally friendly one possible.

People across the UK are set to sizzle on what could be the hottest day of the year so far. Temperatures are expected to reach 33℃ for four consecutive days,     1     concerns there could be hundreds of heat related deaths in the UK.

A Met Office amber weather warning for extreme heat comes into     2     today for almost all of England south of Manchester and parts of eastern Wales. It is expected to last until Sunday with temperatures     3     to climb to 36℃.

Temperatures are not expected to drop below the low 20℃ in some areas, even at night. Older people, young children and those with     4     health conditions are more likely to experience adverse health effects, the Met Office said.

“Compared to the July record-breaking heat, this event will be less     5    , but last longer, which could actually have a greater impact on people’s health,” Hannah Cloke, a professor of hydrology at the University of Reading, said.

Both countryside and urban areas are tinder dry,     6     people to take special care. Ten fire engines and about 70 firefighters were called to a grassfire in Rainham, east London, yesterday, the London Fire Brigade said.

The Met Office’s fire     7     index, an assessment of how severe a fire could become if one were to start, is very high for most of England and Wales. The village of Northend in Oxford shire became the first place in the UK to run dry in the hot     8    . Thames Water, which operates in the area, sent water tankers and handed out bottles. The company has said that as a severe drought has made ground conditions worse for water     9    , it will bring in a hosepipe ban for its 15 million customers across London, Surrey and Gloucestershire in the “coming weeks”.

Experts have also warned that cliff     10     could become more of a risk on south coast beaches. Vanessa Banks, of the British Geological Survey, said that clay-like sediments will shrink as soils experience large changes in volume due to changes in water content.