One day, “supercharged plants” may help feed people around the world. Supercharged plants are ones that grow faster than normal plant life. Scientists can speed up the growth by modifying, or changing, the structure of plants' genes. The modifications make them react quickly to changes in light. This all has to do with photosynthesis(光合作用), the process in which plants turn sunlight, carbon dioxide and water into food.
Plants grow fastest in the sun. That is when they make the most food for themselves. But their rate of growth can slow when things like clouds or trees block sunlight. But when the sun returns, it can take many minutes for growth to speed up again.
This can be a problem because it means some of our most important crop plants are not as productive as they could be. Researchers say demand for food is expected to increase up to 70 percent by the middle of the century. They also note rising temperatures on Earth's surface. That is why they are looking for ways to improve photosynthesis and make plants more productive.
Steve Long is a plant biologist at the University of Illinois. He wanted to find a way to help plants get back up to speed quickly after a period of darkness. So he and his team added genes that shortened the recovery time. It also increased the speed at which the plants grew. His modified plants grew up to 20 percent more than untreated ones.
In Long's study, his group used a form of genetic engineering called transgenics (转基因). It means taking genes from one plant, then putting them into another. Now they are experimenting soybeans, rice, cowpeas and cassavas.
1. What is the advantage of supercharged plants?A.They can grow more quickly. |
B.They can grow in severe conditions. |
C.They can offer high-quality grains. |
D.They can replace normal plants. |
A.Too hot weather. | B.Old farming methods. |
C.Lack of sunlight. | D.Too much sunlight. |
A.To find out what makes plants grow slowly. |
B.To create a new plant that can grow with weak sunlight. |
C.To find another way to help plants benefit each other. |
D.To make plants recover quickly when the sun returns. |
A.By changing their nature. | B.By adding new genes to them. |
C.By developing new plants. | D.By supplying more sunlight. |
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【推荐1】Do you enjoy eating ketchup on your fries? If so, you must like the essential ingredient in the sauces, tomatoes. The tomato originally comes from South America and has been eaten by people there for thousands of years. Today, tomatoes are popular all over the world. However, when they were first introduced, there was quite a bit of controversy and apprehension surrounding them.
Tomatoes were first planted by the Aztecs (阿兹特克人) in Central America. In fact, ancient Aztec writings mention recipes for dishes of tomatoes. Spanish soldiers conquered the Aztecs and brought tomato seeds back with them to Europe. In Europe, these yellowish tomatoes were first called “apples of gold “. For a long time, people in Northern Europe and North America did not eat these “apples of gold”. The tomato plant looked similar to the nightshade plant, a deadly poison, so they were afraid to eat them. German people even thought that if someone ate tomatoes, he or she would change into a werewolf(狼人). But finally, by the mid-1800s people all over the world had accepted the tomato.
However, the tomato was due for more controversy. Do you think the tomato is a fruit or vegetable? Actually the tomato is a fruit. But in America, the tomato is a vegetable by law. Why is the tomato legally a vegetable in America? In the 1800s, there was no import tax in fruit from other countries. At that time, many tomatoes were coming from other countries into America, and American tomatoes farmers became worried about making a living. The government made the tomato a vegetable by law so that non-American tomatoes would be taxed.
Actually, it is easy to tell that the tomatoes is really a fruit. Cut into a tomato and look inside. You can see many seeds in the center, which is one sign of a fruit. In fact, tomatoes are similar to strawberries. Both have seeds inside, and both grow from the flowers of a plant. And both have delicious flesh surrounding the seeds. Tomatoes and strawberries are actually in the same family.
1. What is the main idea of this reading?A.How our ideas about tomatoes have changed |
B.How to grow tomatoes |
C.The history of tomatoes planting. |
D.The history of famous tomato dishes. |
A.They thought tomatoes could change them into monsters. |
B.They though tomatoes were similar to a deadly plant. |
C.They thought tomatoes cost too much to grow. |
D.They thought tomatoes were poisonous. |
A.Both a fruit and a vegetable. | B.A kind of vegetable. |
C.A kind of fruit. | D.Neither a fruit nor a vegetable. |
A.Tomatoes do not grow very bug. |
B.The inside parts are similar. |
C.They grow on tree. |
D.Summer is the best time to pick them. |
【推荐2】Walk through the Amazon rainforest today and you will find it is steamy, warm, damp and thick. But if you had been around 15,000 years ago, during the last ice age, would it have been the same? For more than 30 years, scientists have been arguing about how rainforests like the Amazon might have reacted to the cold, dry climates of the ice ages, but until now, no one has reached a satisfying answer.
Rainforests like the Amazon are important for mopping up CO2 from the atmosphere and helping to slow global warming. Currently the trees in the Amazon take in around 500 million tons of CO2 each year: equal to the total amount of CO2 giving off in the UK each year. But how will the Amazon react to future climate change? If it gets drier, will it still survive and continue to draw down CO2 ?
Scientists hope that they will be able to learn in advance how the rainforest will manage in the future by understanding how rainforests reacted to climate change in the past. Unfortunately, getting into the Amazon rainforest and collecting information are very difficult. To study past climate, scientists need to look at fossilized pollen, kept in lake mud. Going back to the last ice age means drilling deep down into lake sediments (沉淀物)which requires specialized equipment and heavy machinery. There are very few roads and paths, or places to land helicopters and aeroplanes. Rivers tend to be the easiest way to enter the forest, but this still leaves vast areas between the rivers completely unsampled(未取样).So far, only a handful of cores have been drilled that go back to the last ice age and none of them provide enough information to prove how the Amazon rainforest reacts to climate change.
1. What does the underlined phrase “mopping up” in the second paragraph mean?A.Giving up. | B.Giving out. |
C.Wiping out. | D.Taking in. |
A.It’ll get drier and continue to remove CO2 . |
B.There is no exact answer up to present. |
C.It’ll get warmer and then colder and drier. |
D.It’ll remain steamy, warm, damp and thick. |
A.It’s important to drill deep down into lake sediments to collect information. |
B.It’s impossible to prove how climate changes in the Amazon rainforest. |
C.It’s hard to collect information for studies of the past climate in the Amazon rainforest. |
D.It’s necessary to have specialized equipment and machinery to study the past climate. |
A.Studies of the Rainforests |
B.Climates of the Amazon |
C.Secrets of the Ice Age |
D.Changes of the Rainforests |
【推荐3】Winter begins in the north on December 22nd. People and animals have been doing what they always do to prepare for the colder months. Squirrels(松鼠), for example, have been busy gathering nuts from trees. Well, scientists have been busy gathering information about what the squirrels do with the food they collect.
They examined differences between red squirrels and gray squirrels in the American state of Indiana. The scientists wanted to show how these differences could affect the growth of black walnut(黑胡桃) trees. The black walnuts is the nut of choice for both kinds of squirrels. The black walnut tree is also a central part of some hardwood forests.
Rob Swihart of Purdue University did the study with Jake Goheen, a former Purdue student now at the University of New Mexico. The two researches estimate(估计) that several times as many walnuts grow when gathered by gray squirrels as compared to red squirrels. Gray squirrels and red squirrels do not store nuts and seeds in the same way. Gray squirrels bury nuts one at a time in a number of places. But they seldom remember where they buried every nut. So some nuts remain in the ground. Conditions are right for them to develop and grow the following spring. Red squirrels, however, store large groups of nuts above ground. Professor Swihart calls “death traps for seeds”.
Gray squirrels are native to Indiana. But Professor Swihart says their numbers began to decrease as more forests were cut for agriculture. Red squirrels began to spread through the state during the past century.
The researchers say red squirrels are native to forests that stay green all year, unlike walnut trees. They say the cleaning of forest land for agriculture has helped red squirrels invade Indiana. Jake Goheen calls them a sign of an environmental problem more than a cause.
1. The study done by Rob Swihart and Jake Goheen is to ________.A.find out how squirrels collect walnuts |
B.learn squirrels’ influence on black walnut trees |
C.do something to get rid of squirrels |
D.save the forests in the American state of Indiana |
A.the way they gather the walnut | B.the time they have winter sleep |
C.the place they have winter sleep | D.the place they store the walnuts |
A.Agricultural in Indiana has been well developed. |
B.Gray squirrels will be replaced by red squirrels in Indiana. |
C.The spread of red squirrels will do harm to walnuts trees in Indiana. |
D.The government will take some measures to protect black walnut trees. |
【推荐1】Is there a way to turn back the aging process in people? For centuries, people have been looking for a “fountain of youth.” The idea is that if you find a magical fountain, and drink its water, you will not age.
Researchers in New York did not find an actual fountain of youth, but they may have found a way to turn back the aging process. It appears that the answer may be called the hypothalamus, which is part of your brain. It controls important body activities, including growth, the way we process food and so on. Researchers found that hypothalamus neural stem cells (干细胞) also influence how fast aging takes place.
Dongsheng Cai was the leading researcher in a study on aging in mice. He and his team reported their findings. “when the hypothalamus starts aging, particularly the loss of hypothalamus stem cells, so does the body.” he said.
Using this information, the researchers began trying to activate (激活) the hypothalamus in laboratory mice. The results show that the treatment slowed aging in the animals. “When we injected the hypothalamus stem cells to the middle-aged mice, the mice aged slowly and they could also live longer.”
But these results were just from studying mice in a laboratory. If the mice can live longer, does that mean people could have longer lives? The next step is to see if the anti-aging effects also work in human beings. If so, they say the findings could lead to new ways to help doctors identify and treat age-related health problems.
1. Why does the author mention the “fountain of youth” in the first paragraph?A.To explain what the “fountain of youth” is. |
B.To introduce the hypothalamus. |
C.To show how to find the “fountain of youth”. |
D.To help people find the “fountain of youth”. |
A.The brain. | B.The aging process. |
C.Hypothalamus. | D.The stem cell |
A.They have found a way to turn back the aging process. |
B.The brain controls growth, reproduction and the way we process food. |
C.The decrease of hypothalamus stem cells can lead to aging. |
D.The finding has been applied to human beings. |
A.The Secret of Youth |
B.A New Discovery about Aging |
C.The Ways of Slowing Down Aging |
D.Hypothalamus — the Fountain of Youth |
【推荐2】There are many colors in nature. But do you think that a color has weight? I think you'll say "no". But I'm afraid you are wrong. If you don't believe it, you may do a small experiment.
First, put two objects with the same weight into two boxes. Then cover the boxes. Third, wrap one box with a red piece of paper, the other one with white piece of paper. OK. Now hold the boxes with your hand one by one. It is certain that you will think the red one is a little heavier.
Why do you think so? A scientist found that different colors have different weights in man's mind. That is to say, every color has its own weight in our mind.
The scientist told us that colors also have smell. Can you smell the color? Of course not. Then why did the scientist say so? That is because every color stands for kind of light with a certain wavelength(波长). It reaches our brain through sense organs.
According to this discovery scientists say that people accept the colors they like, and refuse the colors they hate. So your body and mind will be healthy by using the colors you like. Or you'll be nervous or even get ill. For example, you like blue and hate red. If you stay in a room with red windows, wallpaper and furniture for two hours, you'll feel you have been there for four hours. But if the room is blue, you'll feel you have been there for only an hour. And if a person walks out of a blue room and into a red room, his temperature will rise. That means our body temperature will change with different colors.
1. What can we know from the experiment?A.The two boxes have the same weight. |
B.Colors can change the weight of an object. |
C.The red paper is heavier than the white paper. |
D.Colors have different weights in people's mind. |
A.The meal of colors is changeable. |
B.People can sense the light from colors. |
C.People can smell the colors through the nose. |
D.All the colors have the same smell for the blind. |
A.White color is heavier than red color. |
B.People nay get ill if they refuse the colors they don't like. |
C.People can stay longer in red rooms than in blue rooms. |
D.People's body temperature will change with different colors. |
A.short novel | B.news report |
C.science report | D.advertisement |
【推荐3】For decades, India’s time zone has been a hotly debated issue. Back in 1884 when time zones were officially established, two time zones were used — Bombay Time and Calcutta Time. Indian Standard Time (IST) was introduced in 1906, but Calcutta Time and Bombay Time continued to be maintained after
India’s independence in 1947, until 1948 and 1955 respectively. The current single time zone, though a legacy of British rule, is often viewed as a symbol of unity. Yet, not everyone thinks it is a good idea. India stretches 3,000 km from east to west, spanning roughly 30 degrees longitude. This corresponds to a two-hour difference in mean solar time, based on the position of the sun in the sky. Thus, the sun rises nearly two hours earlier in the east than in India’s far west. In Northeastern states, sunrise can be as early as 4 a.m. in summer and sunset by 4 p.m. in winter, much earlier than the official working hours. This results in great loss of daylight hours and more consumption of electricity, and often reduced productivity.
Meanwhile, recent studies point out that the current system leads to a serious problem in education for some students. Nationwide, the school day starts at roughly the same time; thus, children go to bed later and have reduced sleep in west India, where the sun sets later. Such sunset-induced sleep deprivation is more pronounced among the poor, mostly due to their noisy environment and lack of sleep-inducing facilities like window shades or indoor beds. On average, an hour’s delay in sunset time reduces children’s sleep by 30 minutes, and an hour’s delay in annual average sunset time reduces education by about 0.8 years. As a result, children living in locations with later sunsets are less likely to complete primary and middle school education.
Despite various requests and proposals for multiple time zones, the government is keen to retain the current system. Reasons provided include prevention of confusion and safety issues regarding railway and flight operations.
1. Which of the following illustrates the Indian time zone system since 1955?A.![]() | B.![]() |
C.![]() | D.![]() |
A.Noisy. | B.Distant. | C.Flexible. | D.Outstanding. |
A.The number of traffic accidents can be reduced. |
B.Children may have better-quality sleep and education. |
C.India may have more energy resources to generate electricity. |
D.The country may rid itself of the impact of British colonization. |
![](https://img.xkw.com/dksih/QBM/2022/7/30/3033950050820096/3035395069665280/STEM/0c20d0d321eb48edb1516ce39025cbb7.png?resizew=240)
A.7 p.m. | B.6 p.m. | C.5 p.m. | D.4 p.m. |