Scientists think they have the answer to a puzzle that confused even Charles Darwin: How flowers evolved and spread to become the most important plants on Earth.
Flowering plants, or angiosperms, make up about 90% of all living plant species. In the distant past, they outpaced (超过) plants such as conifers and fems (针叶植物和蕨类植物), but how they did this has been a mystery. New research suggests it is due to genome (基因组) size.
Hundreds of millions of years ago, the Earth was dominated (支配) by ferns and conifers. Then, about 150 million years ago, the first flowering plants appeared on the scene. They quickly spread to all parts of the world, changing the landscape from muted green to a variety of colours.
Why angiosperms were successful and diverse on Earth has been debated for centuries. Charles Darwin himself called it a“mystery”, fearing this apparent sudden leap might challenge his theory of evolution.
Kevin Simonin from San Francisco State University in California, US and other researchers wondered if the size of the plant’s genetic material — or genome — might be important. They analysed data held by the Royal Botanic Gardens, Kew, on the genome size of hundreds of plants, including flowering plants, gymnosperms (a group of plants including conifers) and fems. They then compared genome size with anatomical (结构上的) features.
This provides “strong evidence”, that the success and rapid spread of flowering plants around he world is due to “genome downsizing.”
By shrinking the size of the genome, which is contained within the nucleus of the cell, plants can build smaller cells. In turn, this allows greater carbon dioxide uptake (摄入) and carbon gain from photosynthesis, the process by which plants use light energy to turn carbon dioxide and water into sugar and oxygen.
The researchers say genome — downsizing happened only in the angiosperms, and his was “a necessary condition for rapid growth rates among land plants”.
1. What do you know about angiosperms?| A．They are dominant plants on Earth. |
| B．They are rare plants in South Africa. |
| C．They are topical plants in South Asia. |
| D．They are extinct plants in the world. |
| A．Charles Darwin was confident of his theory of evolution |
| B．Kevin Simonin is probably an American biologist |
| C．Kev in Simonin works in the Royal Botanic Gardens, Kew |
| D．Charles Darwin succeeded in figuring out the flower evolution |
| A．The weaker conifer. |
| B．The larger nucleus. |
| C．The smaller genome. |
| D．The stronger cell. |
| A．How Angiosperms Conquered the World? |
| B．What Puzzle Confused Even Charles Darwin? |
| C．Why Gymnosperms Were Successful on Earth? |
| D．When Angiosperms Outpaced Conifers and Fems? |
相似题推荐
【推荐1】For more than 140 years, fishers in Laguna, Brazil have formed an unusual partnership with local dolphins. As soon as the fishers spot a dolphin waving its tail, lifting its head, and diving deeply, they race into the water with their nets. Now, a new study suggests the dolphins are willing partners in this cooperation and that the animals may be guiding the people. They pay close attention to the humans, timing their actions to maximize their catch. Over the years, dolphins have been showing the fishers “where to stand and when to get ready to throw their nets” in the dark waters. It’s almost as if the dolphins are training the humans.
As much as the fishers were watching the dolphins, the dolphins were also watching the fishers, the study found. Both species must time their actions correctly to catch fish. The people wait with their nets at the ready for a dolphin to approach closely. When a dolphin sees a ready fisher, the animal will give a tip, usually that deep dive, which tells the fisher the mullet (鲻鱼)are right there and it’s time to cast their net. Sometimes, either dolphin or fisher will respond incorrectly, and neither catches fish. Yet, the scientists reported that of nearly 3000 recorded fishing attempts, nearly 46% were successful. To ensure this accuracy, fishers must understand the dolphins’ tips, learning them over time, even it can say. “The dolphins are almost like teachers.”
Other populations of dolphins have also been known to cooperate with human fishers, rushing fish toward shore or into nets off eastern Australia, Mauritania, and Southeast Asia. But these practices have either disappeared or are in decline.
The same fate likely faces the Laguna dolphins if the mullet numbers, which have dropped over the past decade because of overfishing, continue to decline. The practice may escape such a fate, if Brazil regards this dolphin-fisher relationship a cultural heritage, as the scientists propose. “Without mullet,” the expert says, “this partnership will end.”
1. How do the dolphins guide the fishers to catch the fish?| A．By constantly attacking fish. |
| B．By making strange voices. |
| C．By pulling the nets. |
| D．By using body languages. |
| A．Introduce a new topic for discussion. |
| B．Provide suggestions for the readers. |
| C．Add some background information. |
| D．Conclude the previous paragraphs. |
| A．It has disappeared. |
| B．It develops friendly. |
| C．It needs to be protected. |
| D．It becomes a cultural heritage. |
| A．Humans live harmonious with dolphins. |
| B．Humans and dolphins team up to catch fish. |
| C．Humans were taught to catch fish by dolphins. |
| D．Humans in Brazil rely on the dolphins for fishing. |
【推荐2】Is it to their body temperature? Save energy? Find food? Tiger sharks at Ninglaoo Reef are thought to search the seafloor for prey(猎物) as they dive down and scan for direction as they swim up to the surface. But could there be other reasons why the sharks continuously move up and down?
That’s what Sammy is hoping to find out for her Ph.D. research. Sammy attached tracking devices to 24 tiger sharks. Best described as Fitbits for sharks, the devices recorded activity rates and other data 20 times a second. Fitbits also contained video cameras, so Sammy could see the habitats the sharks moved through and the animals they met. She watched how the sharks reached to prey and how the prey reached to them.
Tiger sharks can be pretty lazy --- something as simple as a turtle noticing a shark and turning away could cause the shark not to bother hunting it. Stomach content analysis has found their normal prey items, such as turtles, rays and fish. But it has also found some really interesting things, such as licenses, cans and nails.
Sammy says that studying tiger sharks can help her better understand the ecosystem as a whole. How they move through water and feed can help her figure out how they might be influencing animals beneath them in the food chain.
“My time watching tiger sharks hunt was the best month of my Ph.D., if not any life.” Sammy says. “At first, I was a bit apprehensive about it...getting that close to some very big animals. But they were very chilled(温驯) once you had them controlled alongside the boat. They’d just sit there, you’d attached the tracking devices, you’d take the line off and they’d just swim off really calmly, it was pretty amazing to see. They’re just absolutely beautiful animals.”
1. Why does Sammy do her research?| A．To find some scientific data. |
| B．To develop others’ interest in tiger sharks. |
| C．To find out how tiger sharks move. |
| D．To further understand tiger sharks’ moving. |
| A．It’s of great benefit. |
| B．It’s a tiresome job. |
| C．It’s filled with challenges. |
| D．It’s simple and calls for little efforts. |
| A．Curious. | B．Doubtful. |
| C．Fearful | D．Enthusiastic. |
| A．How do tiger sharks find food? |
| B．Why do tiger sharks dive? |
| C．What can we do to protect tiger sharks? |
| D．What roles do tiger sharks play in the food chain? |
【推荐3】Listening to the radio is better at preventing dementia (痴呆) than exercise, a new study suggests. Dementia is one of Britain’s biggest killers, with one in ten male deaths caused by the neurodegenerative (神经退行性的) condition, and one in eight women.
But scientists have long believed that some hobbies and activities can protect the brain by delaying and potentially even completely protecting against the disease.
A large-scale review from scientists at Peking University in Beijing reviewed 38 different studies looking at what pastimes are most beneficial. The data included more than two million people and found that leisure activities were effective at protecting against the disease, lowering the risk by 17 percent, but some hobbies were found to be better than others. Mental activity — which includes reading, writing, watching television, listening to the radio and playing a musical instrument — was found to reduce the risk by 23 percent. In contrast, physical activity, including walking, running, swimming, dancing and yoga, lowered risk by just 17 percent. However, this was still better than people whose leisure time was spent doing social activities like visiting friends, going to church or volunteering, as this saw risk drop by just 7 percent.
“This meta-analysis suggests that being active has benefits, and there are plenty of activities that are easy to incorporate into daily life that may be beneficial to the brain,” said study author Dr Lin Lu of Peking University. “Our research found that leisure activities may reduce the risk of dementia. Future studies should include larger sample sizes and longer follow-up time to reveal more links between leisure activities and dementia.”
Dr Sara Imarisio, head of research at Alzheimer’s Research UK, said: “There isn’t any conclusive evidence for particular brain training programmes or activities that are especially good for staying sharp, but activities that are mentally challenging, sociable and also enjoyable are likely to be better for the brain than spending time alone or engaged in passive hobbies.”
1. Which of the following activities lowers the chance of developing dementia most according to Peking University’s review?| A．Swimming. | B．Watching television |
| C．Volunteering. | D．Visiting Friends. |
| A．More assistance. | B．Wider data. |
| C．Longer trip. | D．Bigger budget. |
| A．To present the background. | B．To put forward a concept. |
| C．To provide support | D．To make a prediction. |
| A．Scientists finally found Britain’s biggest killer |
| B．Sad truth behind people suffering from Dementia |
| C．Unexpected health benefits of listening to the radio |
| D．The very simple tasks may keep dementia away |
【推荐1】The world celebrates Earth Day every year on April 22. But one school in Maryland tries to honor Earth Day every day.
Children at that school love being outside in the open air, running after each other, sliding and swinging on playground equipment. And children at St. James Children’s School also have fun by observing worms and picking up trash in the school yard. Besides, they learn to save water and electricity. They also recycle and reuse things. And every spring they get the soil ready to plant flowers and vegetables in the school garden.
Rebecca Boker teaches the children the importance of taking care of the Earth. She said, “If children learn it early on when they are younger, it will become part of their daily lives. It’s not something they have to think twice. It should be something that everyone does.”
St. James children observe the growth of plants from seeds to sprouts in cups kept in the classroom. Then they watch the plants continue to grow after placing them in the garden. The students also observe the lifecycle of butterflies and other insects and learn about rain and sea life. They try to use as much recycled material as possible.
But do these very young children really get the message that their teachers try to communicate? Ms. Boker says yes. “Oh they do. They completely understand,” she said.
On April 22 the kids at St. James will go out to the school’s garden for the yearly clean-up. But for them, Earth Day will continue for the school days ahead as well.
1. Rebecca Boker thinks that children should ________.| A．think twice before they do anything | B．make it a habit to take care of the Earth |
| C．spend less time on their schoolwork | D．do what everyone does in their daily lives |
| A．spend most of their time observing things | B．don’t have a chance to learn about sea life |
| C．make money out of recycling waste | D．know a lot about nature through observing things |
| A．children at her school don’t like doing what they are told to do |
| B．teachers at her school communicate with the students very carefully |
| C．children at her school know the importance of protecting the Earth |
| D．children at her school are much smarter than students at other schools |
| A．They pick up trash in the streets. | B．They observe the growth of plants. |
| C．They clean up the school’s garden. | D．They plant trees in the school’s garden. |
【推荐2】Triantha Occidentalis, commonly known as the western false asphodel (西部假水仙), which has been known to science since 1879, is a herb-like plant found in abundance along North America’s West Coast. But it is only recently that researchers discovered the innocent-looking plant’s desire for insects.
“We had no idea it was carnivorous (食肉的),” says botanist Sean Graham. “This was not found in some exotic tropical location, but really right on our doorstep in Vancouver. You could exactly walk out from Vancouver to this field site.”
While studying the plant, the researchers noticed that Triantha Occidentalis lacked the same gene as other carnivorous plants. Since the plant grows in the same wet, sunny habitat with nutrient-poor soil as other carnivorous plants, they wondered if it caught insects for nutrition as well. “And at the same time they have sticky stems (茎),” Graham said. “So, I wonder if this could be a sign that it might be carnivorous.”
To test whether it is carnivorous, scientists marked fruit flies with nitrogen-15 isotopes (氮-l5同位素). By collecting the plants the fruit flies visited and comparing the nitrogen levels of different plants, the researchers found that Triantha Occidentalis was able to get more than half of the nitrogen it needed, suggesting that it absorbs nitrogen from the fruit flies. Additionally, the digestive enzyme (消化酶) released by the sticky hairs in flower stems was similar to that found in other carnivorous plants.
Usually, the deadly trap of carnivorous plants grow far away from the flower to prevent accidentally killing pollinators (授粉者), while the western false asphodel traps insects near flowers. The scientists say this is the first time they have met the deadly trap on the flower’s stem, and the sticky hairs on the stem of Triantha Occidentalis can only catch small insects, not the larger bees or butterflies involved in pollination.
“It’s a good reminder that we still don’t know much about the ecology of a lot of individual plant species, even in well-known environments,” says Dr. Qianshi Lin.
1. What does Graham stress in paragraph 2?| A．The discovery is made in the local place. |
| B．Carnivorous plants grow in the hottest places. |
| C．Triantha Occidentalis is very common. |
| D．Vancouver is home to various carnivorous plants. |
| A．The nitrogen. | B．The digestive enzyme. |
| C．The flower. | D．The nutrition. |
| A．Its fruit. | B．Its leaves. |
| C．Its stem. | D．Its roots. |
| A．A new species of local flower is discovered. |
| B．A carnivorous flower in the wild grows well. |
| C．A flower gives off strange smell to attract insects. |
| D．An innocent-looking plant turns out to be carnivorous. |
【推荐3】You’ll boost your brainpower if you brave the unknown, says our memory expert, Jonathan Hancock.
There’s a lot to cope with when you go off to university, and the academic work is just the start. There are new friends to meet, new opportunities to choose between, new responsibilities to accept... and, for most students, a completely new city to explore.
We recently drove our daughter Evie 150 miles to start life as a fresher. It was a struggle to find the car park, let alone navigate the maze of corridors that led to her room. Before we left that evening, we’d taken her to the local supermarket, and we knew that she had flatmates and phone apps to get her orientated. But the scale of the challenge ahead was clear — to find her way in an unfamiliar world.
The good news for Evie — and learners everywhere is that exploring new habitats is hugely beneficial to memory. In a recent study, volunteers walked around a simulated forest environment. Then some of them took the same walk again, while others explored a different forest. And that second group performed significantly better in memory tests straight after. According to the researchers, that was because navigating the new environment stimulated their dopamine (多巴胺) systems-setting up their brains for learning.
So leaving home to study for a degree makes perfect sense. What’s more, young minds seem to gain most from being in strange surroundings. But we may all be able to gain some of the benefits, even if it’s just by stimulating our senses and challenging our thinking skills. Here are three things to try:
(1) Go somewhere new to tackle an upcoming learning task—like memorizing a speech in the library or revising for an exam on a park bench — and take an unfamiliar route to get there.
(2) Play video games that get you moving through new landscapes. Then see whether it improves your success with other learning tasks, like practising a dance or mastering phrases for a foreign trip.
(3) Get lost in your imagination! To warm yourself up for learning, picture a city you know well, but imagine you’re stranded in a part of it that you’ve never visited. Then try to fancy exactly how you’ll get out.
1. What happened when they sent their daughter to her school according to Paragraph 3?| A．They found a park for all their efforts. | B．They were new to the surroundings. |
| C．They got lost in the maze of corridors. | D．They had no phone apps to rely on. |
| A．Taking an unfamiliar route to go home. |
| B．Playing some video games that help you explore new surroundings. |
| C．Getting addicted to playing video games before revising for the exam. |
| D．Imagining yourself getting out of a new city before memorizing a speech. |
| A．Because their dopamine systems were activated. |
| B．Because they entered the same environment twice. |
| C．Because they had flatmates and phone apps to help them. |
| D．Because they walked around a simulated forest environment. |
| A．The need for finding parking spaces in unfamiliar cities. |
| B．The impact of exploring a new environment on our minds. |
| C．The benefits of playing video games for improving learning tasks. |
| D．The significance of picturing familiar cities for memory enhancement. |
【推荐1】Four surprising ways algae (藻类) are driving innovation
Algae can be a double-edged sword. Increased human activity and climate change have caused explosions of algae populations in water bodies around the world sometimes choking entire ecosystems of sunlight and oxygen. Even though they are so closely associated with humanity’s negative impact on Earth, algae could also play key roles in helping fight pollution, viruses, and more.
Filtering (过滤) water.
With microplastic pollution documented in almost all water bodies, a recent study shows that through absorption, algae can help filter microplastics out of water.
Fueling air travel.
Fighting viruses.
Red algae can prevent the replication (复制) of some viruses, including COVID-19, according to a 2020 study.
In 2019, freshwater algae were launched into space to turn the carbon dioxide exhaled (呼出) 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.
| A．Making space food more nutritious. |
| B．Making long-term space travel possible. |
| C．These are several ways algae are solving modern problems. |
| D．Some algae can also filter chemicals that can be used in fertilizers. |
| E．Brown algae have been shown to stimulate the body’s immune system. |
| F．Algae can produce more effective biofuels than traditional sources like soybeans. |
| G．It aims to harvest algae for energy while keeping the environment pollution-free. |
【推荐2】How to Prepare Houseplants for Fall
It would be easy to think that since houseplants live inside, they don't really experience seasons as their outdoor plants do.
Remove any dead or dying leaves. Find any yellowing or brown leaves.
Be mindful of extreme temperatures. Hot or cold extremes can stress（使……紧张）plants out.
Repot（移植）if needed. Spring is the best time to repot houseplants because that's when they begin to grow rapidly. But if any of your babies have had an active summer and are too small for their pot, now is a good time as well. Lift the plant out of the pot and check how the roots look.
Be careful with watering. Over-watering is one of the most common houseplant mistakes. Unless you have especially thirsty species or a very dry home, wait at least a few days in between watering.
| A．The plants under stress will die soon. |
| B．If they seem crowded, it is time to repot. |
| C．So be careful about where your plants are living. |
| D．Bring them in if they've been vacationing outside. |
| E．Pay attention to whether there are harmful insects. |
| F．It's true that they are provided more protection inside. |
| G．Cut off the leaves of these colors at the base or at the soil. |
【推荐3】Don’t Buy Fertilizer (肥料)! It Is All Around You.
The cost of everything seems to be rising around the world. So, growing our own food is a good way to save money. However, the cost of gardening has also been rising. Now make your own!
Cut grass
Consider cut grass. If you leave cut grass on the land, you may not need fertilizer. As grass breaks down, it benefits the soil.
However, do not use fresh cut grass in garden beds. It will burn your plants.
Compost (堆肥) is best for soil
Compost is the best thing you can add to soil. Compost helps to control how much water stays in the soil. It keeps dry soil wet. Compost also adds nutrients (营养) to the soil.
To make your own compost, simply collect fruit and vegetable leftovers. Do not add meat, milk, or fats. You can keep the food leftovers in a bowl in your kitchen.
Use leftover from around your house
Are you a fish owner? Plants can also be helped from used fish-tank water. This water is rich in nutrients. Do you cook vegetables in water? If so, save it!
And water from cooked eggs is full of calcium (钙). This is especially useful for tomatoes. Just make sure to let the water cool to room temperature before using on your plants.
You can even use egg shells (壳). Dry out the egg shells.
| A．They are good for plants. |
| B．Then break them up into tiny pieces. |
| C．This will help plants to continue to grow. |
| D．The same can be done with banana wastes. |
| E．Whenever it fills up, bury it directly in the garden earth. |
| F．Just be sure to bury them at least 25 to 30 centimeters deep. |
| G．The water is filled with useful things that could help your garden. |
