1. How many people died in a landslide in 2003?
| A．About two hundred. | B．Over one thousand. | C．About two thousand. |
| A．Growing grass. | B．Cutting down trees. | C．Growing population. |
| A．Growing more forests. |
| B．Chopping down the old forests. |
| C．Getting busy in protecting our country. |
2 . 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. |
3 . Warmer oceans can cause coral (珊瑚) bleaching. Bleaching happens when the coral, colonies of tiny animals called polyps, lose colored algae (藻类) living in their bodies and turn completely white. Without the algae, the coral loses its main food source and can die.
In 2021, the United Nations reported a 14 percent loss of corals across the world largely from rising sea temperatures in the previous 13 years. Australia declared mass bleaching events in 2022 across large parts of the Great Barrier Reef, the fourth since 2016.
Reefs in Hawaii, Florida, and the Caribbean were all severely affected, but thankfully some coral areas were not. Scientists looked into the characteristics of these corals and their ecosystems to see how others could be protected. Warm water reefs in the tropics are the worst affected by bleaching, but they also contain corals with better heat resistance.
Research is focused on finding genes for heat tolerance so that they can be passed on to future generations. Biologists mix corals that are more resilient to higher temperatures with those that are not and the resulting hybrid generation has a better chance of survival.
Researchers in Florida’s reefs have been using ocean nurseries to replant coral with batches that contain genes resistant to heat, acidification, and disease. Those areas have recovered within a year.
Other projects like Revive and Restore are using methods like preserving older coral populations’ sperm and eggs (biobanking) and using corals with better adaptability characteristics in breeding. The project also believes that boosting biodiversity by restoring (恢复) seabirds to islands, and ridding them of invasive species like rats, helps coral reefs thrive.
Ultimately, scientists say that without a serious reduction in greenhouse gas emissions, 99 percent of the world’s coral reefs will be gone by the end of the century. There is a limit to how quickly coral can adapt, especially given the rate of climate change. Computer simulations have shown that mild or moderate warming allows coral to adapt, but if temperatures rise rapidly then extinction is certain.
1. What mainly causes coral bleaching?| A．Loss of algae. | B．Lack of food. |
| C．Warm oceans. | D．Ocean pollution. |
| A．Coral reefs in tropics are easier to bleach. |
| B．Some corals are found better to resist heat. |
| C．Coral reefs in some areas are badly affected. |
| D．Ecosystems in some coral areas are destroyed. |
| A．Breeding hybrid generation with heat resistance. |
| B．Replanting batches of corals containing diseases. |
| C．Restoring seabirds of islands and invasive animals. |
| D．Setting no limitation of greenhouse gas emissions. |
| A．Botany. | B．Culture. | C．Nature. | D．Education. |
4 . Increased human activity and climate change have caused a rise of algae (藻类植物) in water bodies around the world—sometimes choking ecosystems of sunlight and oxygen. In more extreme cases, they can produce dangerous poisons that can sicken or kill people and animals. But the plenty of algae could prove crucial as our population rises beyond eight billion people worldwide because algae are crops that don’t need land, freshwater, or fertilizer to fill nutritional gaps.
And even though they are so closely associated with human’s bad impact on Earth, algae could also play vital roles in slowing climate change and helping fight against pollution, viruses, and more. With microplastic pollution documented in almost all habitats related to water, a study showed that algae can help filter microplastics from water. Algae can also filter chemicals that can be used for fertilizer.
Algae can produce more effective biofuel than traditional sources. Rescarchers at a German algae growing facility are already using it to fuel plane. Researchers believe this and other sustainable fuels could reduce carbon released from airplanes by up to 80 percent.
Animal feed containing a kind of red algae reduces harmful methane(甲烷)released from cattle by more than 80 percent. The addition works by changing the environment in a cow’s stomach, stopping the production of methane before it can be released.
Red algae can stop the copies of some viruses, and have been shown to stimulate the body’s immune (免疫的) system and could become a powerful anti-HIV medicine.
In 2019, freshwater algae were launched into space to change the CO2 breathed out by astronauts on the International Space Station into oxygen. Since algae are also high in protein, they could replace up to 30 percent of astronaut food in the future.
1. What can we know about algae from the first paragraph?| A．Better late than never. | B．Every coin has two sides. |
| C．All is well that ends well. | D．Two heads are better than one. |
| A．They avoid climate change. | B．They absorb pollutants in the air. |
| C．They reduce microplastics in the water. | D．They filter most poisonous chemicals. |
| A．Change animal feed into methane. |
| B．Store carbon released from airplanes. |
| C．Help researchers to create traditional sources. |
| D．Create biofuel and reduce methane in cows’s stomach. |
| A．By helping fight against diseases. | B．By increasing human’s strength. |
| C．By producing more oxygen than other plants. | D．By replacing much food for astronauts. |
