題目列表(包括答案和解析)
Have you ever wondered why the roots of the plants always know which way to grow—into the soil but not above it? Some British scientists have recently solved this mystery.
It turns out that roots have special hairs that tie them into the soil and help them grow their way past obstacles, a team at the John Inners Center in Norwich reports in the February 29 issue of Journal Science.
“The key is in the fuzzy(有絨毛的)coat of hairs on the roots of plants,” says professor Liam Dolan. “We have found a growth control system that enables these hairs to find their way and to become longer when their path is clear.”
Root hairs explore the soil in much the same way a person would feel their way in the dark. If they come across an obstacle, they make their way around until they can continue growing in an opening. In the meantime, the plant is held in place as the hairs grip(緊緊抓住)the soil.
The hairs are guided by a clever chemical trick. A protein(蛋白質) at the tip of the root hairs called RHD2 helps them to take calcium(鈣) from the soil. Calcium makes the hairs grow, and produce more RHD2, and take more calcium.
But when an obstacle blocks the hair’s path, or the hair reaches the surface of the soil, the cycle is broken and growth starts in another direction.
This system gives plants the flexibility to explore a complex environment and to live in even the most unpromising soils, says Dolan.
In poor soils such as in parts of Australia and Africa, native plants have adapted by producing enormous numbers of root hairs. A better understanding of this adaptation will allow scientists to develop hairy rooted crops that can grow in unfriendly environments.
According to Dolan, “Research in the John Inners Center is taking a breeding approach to increase hair length in wheat but it will be some time before new cultivars(栽培變種) are developed.”
1.The passage is mainly about _______.
|
A．why the roots of plants grow into the soil but not above it |
|
B．how the roots of plants grow into the soil but not above it |
|
C．the process of plants growth |
|
D．a growth control system of plants |
2.How does the circle work?
|
A．RHD2 takes calcium from the soil, which makes hairs grow, and produce RHD2 and take more calcium |
|
B．Roots take RHD2 and calcium from the soil and produce RHD2 |
|
C．Roots make hairs grow, and produce RHD2, and take more calcium |
|
D．RHD2 takes protein, which makes hairs grow, and produce RHD2, and take more calcium |
3.We can infer from the last paragraph that ________.
|
A．hairy rooted crops can grow better in unfriendly environments |
|
B．a new cultivar of wheat with long hair has been developed by scientists |
|
C．a new cultivar of wheat with long hair is still on test |
|
D．the roots of plants always know which way to grow |
Commonwealth Games gold winner Liam Killeen is one of England’s most successful Mountain Biking stars. Liam recently came third in the opening round of the World Cup Series.
Do you come from a sporty family?
NO, but my family have encouraged me and supported me from the beginning of my career.
Were there any sports you didn’t like playing at school?
I didn’t do much swimming or cricket. My school focused more on rugby and athletics including cross-country running which I really enjoyed.
How does it feel to represent England?
Good, and it’s a responsibility as well as an honor, whether representing England, as in the Commonwealth Games, or Great Britain as I did in the Athens Olympics (2004). I am proud to represent a nation that is generally well regarded by others.
Which other sports stars do you like?
Everyone who has made it to world class competition level has earned respect. I particularly admire Paula Radcliffe and Lance Armstrong.
What are your hopes for the future?
To have this season continue as successfully as it has started and make the podium in the World Cup in Fort William in May, and at the Mountain Bike World Championship on 27th August this year in New Zealand. In the longer term, to win a medal at the Olympics in Britain and to see more people racing and enjoying mountain biking.
1.The passage is taken from .
|
A．an interview between a reporter and Liam Killeen |
|
B．a daily talk between Liam Killeen and his father |
|
C．a book written by Liam Killeen |
|
D．a speech made by Liam Killeen |
2.Liam Killeen won a gold medal in the .
|
A．World Championships |
B．World Cup |
|
C．Commonwealth Games |
D．Olympic Games |
3..Which of the following is TRUE according to the passage?
|
A．Liam’s family enjoy sports very much. |
|
B．Liam loves swimming and mountain biking |
|
C．Liam took part in the Olympic Games in 2004 |
|
D．Liam’s father also enjoys mountain biking very much |
4.From the passage we can infer that .
|
A．Liam Killeen will win a gold medal in the Olympics in 2012 |
|
B．Lance Armstrong is a world-class sports player |
|
C．Liam Killeen has earned a lot of money |
|
D．Liam has won many gold medals in world competitions |
Have you ever wondered why the roots of the plants always know which way to grow—into the soil but not above it? Some British scientists have recently solved this mystery.
It turns out that roots have special hairs that tie them into the soil and help them grow their way past obstacles, a team at the John Inners Center in Norwich reports in the February 29 issue of Journal Science.
“The key is in the fuzzy(有絨毛的)coat of hairs on the roots of plants,” says professor Liam Dolan. “We have found a growth control system that enables these hairs to find their way and to become longer when their path is clear.”
Root hairs explore the soil in much the same way a person would feel their way in the dark. If they come across an obstacle, they make their way around until they can continue growing in an opening. In the meantime, the plant is held in place as the hairs grip(緊緊抓住)the soil.
The hairs are guided by a clever chemical trick. A protein(蛋白質) at the tip of the root hairs called RHD2 helps them to take calcium(鈣) from the soil. Calcium makes the hairs grow, and produce more RHD2, and take more calcium.
But when an obstacle blocks the hair’s path, or the hair reaches the surface of the soil, the cycle is broken and growth starts in another direction.
This system gives plants the flexibility to explore a complex environment and to live in even the most unpromising soils, says Dolan.
In poor soils such as in parts of Australia and Africa, native plants have adapted by producing enormous numbers of root hairs. A better understanding of this adaptation will allow scientists to develop hairy rooted crops that can grow in unfriendly environments.
According to Dolan, “Research in the John Inners Center is taking a breeding approach to increase hair length in wheat but it will be some time before new cultivars(栽培變種) are developed.”
【小題1】The passage is mainly about _______.
| A．why the roots of plants grow into the soil but not above it |
| B．how the roots of plants grow into the soil but not above it |
| C．the process of plants growth |
| D．a growth control system of plants |
| A．RHD2 takes calcium from the soil, which makes hairs grow, and produce RHD2 and take more calcium |
| B．Roots take RHD2 and calcium from the soil and produce RHD2 |
| C．Roots make hairs grow, and produce RHD2, and take more calcium |
| D．RHD2 takes protein, which makes hairs grow, and produce RHD2, and take more calcium |
| A．hairy rooted crops can grow better in unfriendly environments |
| B．a new cultivar of wheat with long hair has been developed by scientists |
| C．a new cultivar of wheat with long hair is still on test |
| D．the roots of plants always know which way to grow |
Liam Fitzptrick
Liam Fitzptrick was born in Hong Kong and educated at Christ Church, Oxford, graduating with a First in Modern History. He wrote for several regional and international publications before joining Time in 2003. he edits Global Adviser for Time Asia, and is also Time Asia’s senior writer. Liam is married with two daughters and lives in Hong Kong’s New Territories.
Ling Woo Liu
Ling Woo Liu grew up in California, where she was a self—employed writer for Asian—American print and broadcast media. She worked as a television reporter in Beijing and California before earning graduate degrees in Journalism and Asian Studies from the University of California, Berkeley. In 2006, Ling moved to Hong Kong to report for Time Asia.
Bill Powell
Prior to his current post, a senior writer for Time in Shanghai, Bill Powell was Chief International correspondent for Fortune based in Beijing and then New York. He also served as Newsweek bureau chief in Moscow, Berlin and Tokyo. Bill is married to Shanghai native Junling Cui. They have one daughter and live in a house they recently purchased in suburban（郊區）Shanghai.
Austin Ramzy
Austin Ramzy grew up in Iowa. In 1996 he studied Mandarin in Harbin, China, and graduated from Middlebury College with a degree in Asian Studies in 1997. after working as a newspaper reporter in Washington state, he completed journalism school at the university of California, Berkeley has been a reporter for Time Asia in Hong Kong since 2003.
1.The passage is mainly written to ____________.
A. advertise Time Asia B. introduce the publishers of Time Asia
C. introduce the development of Time Asia
D. introduce some of the authors and writes of Time Asia
2.It’s ___________ who majored in History but worked as a writer.
A. Bill Powell B. Liam Fitzpatrick C. Ling Woo Liu D. Austin Ramzy
3.It’s clear that __________ graduated from the same school.
A. Liam Fitzpatrick and Ling Woo Liu B. Bill Powell and Austin Ramzy
C. Ling Woo Liu and Austin Ramzy D. Liam Fitzpatrick and Bill Powell
4.Which is TURE about Bill Powell?
A. He lives in Hong Kong with his family B. He is Time Asia’s senior writer
C. He once studied Mandarin in Northeast China
D. He once worked for Newsweek bureau in New York
Doctors in Britain are warning of an obesity time bomb, when children who are already overweight grow up. So, what should we do? Exercise more? Eat less? Or both? The government feels it has to take responsibility for this expanding problem.
The cheerful Mr. Pickwick, the hero of the novel by Charles Dickens, is seen in illustrations as someone who is plump and happy. In 18th century paintings, beauty is equated （使…等同） with rounded bodies and soft curves. But nowadays being overweight is seen as indicating neither a cheerful character nor beauty but an increased risk of heart disease, stroke and diabetes.
So what do you do? Diet? Not according to England's chief medical officer, Sir Liam Donaldson. He says that physical activity is the key for reducing the risks of obesity, cancer and heart disease. And the Health Secretary John Reid even said that being inactive is as serious a risk factor in heart disease as smoking.
So, having bought some cross trainers, how much exercise should you do? According to Sir Liam Donaldson, at least 30 minutes of moderate activity five days a week. Is going to the gym the answer? Luckily for those who think that running machines are boring, the Health Development Agency believes that physical activity that fits into people's lives may be more effective. They suggest taking the stairs rather than the lift, walking up escalators, playing active games with your children, dancing or gardening. And according to a sports psychologist, Professor Biddle, gyms "are not making the nation fit", and may even cause harm.
There's new scientific evidence that too much exercise may actually be bad for you. Scientists at the University of Ulster have found that unsuitable exercise releases dangerous free radicals that can adversely （oppositely） affect normal function in unfit people. The only people who should push their bodies to that level of exercise on a regular basis are trained athletes.
So, should we forget about gyms and follow some expert's advice to reduce sedentary （久坐不動的） activities and increase exercise in our daily life? After all, getting off the bus a stop early and walking the rest of the way can't do any harm! One final thought. How come past generations lacked gym facilities but were leaner and fitter than people today?
1.Mr.Pickwick and the paintings of the 18m century are used as examples to show that_____.
A. beauty should be overweight
B. a fat man is usually a cheerful character
C. fatness was considered something good at one time
D. fatness leads to an increased risk of disease
2.According to Sir Liam Donaldson, we should_____.
A. go on a diet B. do regular physical activity
C. give up smoking D. go to the gym
3.The underlined phrase cross trainers probably refers to _____.
A. people who help you do exercise B. places where you can do exercise
C. a kind of shoes D. a form of vehicles
4.At present being overweight indicates _____.
A. an increased risk of diseases B. a happier life
C. a cheerful character D. a beauty
5.What is the passage mainly about?
A. how to keep fit and avoid fatness. B. increased risks for overweight people.
C. the dangers of exercise in the gym. D. the benefit of a balanced diet.
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