It happens every spring. Flowers come out everywhere on the same day. But how do plants “know” when to flower?
For years, it has been a difficult question for scientists. But a US research group may have finally answered it—the secret lies in a protein(蛋白质)called FKF1. This helps plants to know when the days become long and when they get short. Then they can tell the seasons are changing.
Researchers found the FKF1 protein when they were studying a plant called Arabidopsis(拟南芥). It is sensitive(敏感的)to sunlight, and can be made active by sunlight.
Plants produce this protein every day in the late afternoon all year. If there is no light at this time, for example in winter when the sun goes down early, the protein won’t be active. But when spring comes and the days get longer, the FKF1 protein can be made active by day light and the plants “know” it is time to flower. “If there is light in the late afternoon, plants will know that the days are getting longer and that it is the best time for flowers to come out,” explained Takato Imaizumi, leader of study. But when conditions are poor for growing, such as during autumn or winter when the weather is cold and days are short, plants won’t flower.
Although researchers have only studied how the FKF1 protein works in the Arabidopsis, they believe that it is the same with many other plants, including crops such as rice and wheat. This could be useful to the agricultural industry.
“If we can control when flowers come out, we might be able to increase crop production,” Imaizumi said.
1. The passage is mainly about ____.
A. how plants “know” when to flower
B. what people can do with plants
C. how seasons are changing
D. what kind of plant Arabidopsis is
2.Scientists found the FKF1 protein when they were____.
A. answering a question
B. controlling the clours of flowers
C. planting flowers in the garden
D. studying a plant called Arabidopsis
3.The best time for flowers to come out is when____.
A. it rains in spring
B. there is light in the late afternoon
C. it is getting dark
D. the sun goes down early
4.Scientists believe that____.
A. other plants also know when to flowers
B. flowers are more valuable than fruits and vegetables
C. people have known how to control when flowers come out
D. if the weather is cold and days are short, plants will flower
九年级英语阅读理解中等难度题
It happens every spring. Flowers come out everywhere on the same day. But how do plants “know” when to flower?
For years, it has been a difficult question for scientists. But a US research group may have finally answered it—the secret lies in a protein(蛋白质)called FKF1. This helps plants to know when the days become long and when they get short. Then they can tell the seasons are changing.
Researchers found the FKF1 protein when they were studying a plant called Arabidopsis(拟南芥). It is sensitive(敏感的)to sunlight, and can be made active by sunlight.
Plants produce this protein every day in the late afternoon all year. If there is no light at this time, for example in winter when the sun goes down early, the protein won’t be active. But when spring comes and the days get longer, the FKF1 protein can be made active by day light and the plants “know” it is time to flower. “If there is light in the late afternoon, plants will know that the days are getting longer and that it is the best time for flowers to come out,” explained Takato Imaizumi, leader of study. But when conditions are poor for growing, such as during autumn or winter when the weather is cold and days are short, plants won’t flower.
Although researchers have only studied how the FKF1 protein works in the Arabidopsis, they believe that it is the same with many other plants, including crops such as rice and wheat. This could be useful to the agricultural industry.
“If we can control when flowers come out, we might be able to increase crop production,” Imaizumi said.
1. The passage is mainly about ____.
A. how plants “know” when to flower
B. what people can do with plants
C. how seasons are changing
D. what kind of plant Arabidopsis is
2.Scientists found the FKF1 protein when they were____.
A. answering a question
B. controlling the clours of flowers
C. planting flowers in the garden
D. studying a plant called Arabidopsis
3.The best time for flowers to come out is when____.
A. it rains in spring
B. there is light in the late afternoon
C. it is getting dark
D. the sun goes down early
4.Scientists believe that____.
A. other plants also know when to flowers
B. flowers are more valuable than fruits and vegetables
C. people have known how to control when flowers come out
D. if the weather is cold and days are short, plants will flower
九年级英语阅读理解中等难度题查看答案及解析
Colorful flowers come out now. It’s wonderful for us to _________ nice flowers everywhere in spring.
A.smell B.taste C.sound D.feel
九年级英语单选题中等难度题查看答案及解析
Colorful flowers come out now. It’s wonderful for us to __________ nice flowers everywhere in spring.
A. smell B. taste C. sound D. feel
九年级英语单项填空中等难度题查看答案及解析
Flowers usually come out ______ spring every year.
A.in B.at C.on D.of
九年级英语单项填空中等难度题查看答案及解析
As the spring comes, the flowers began to _____.
A.come out | B.come in | C.come on | D.come down |
九年级英语单项填空简单题查看答案及解析
When spring comes and the flowers begin to bloom(开花), the bees come out of the hives(蜂房) very early in the morning. 1.
The bee has a long tongue which goes into the flower to suck(吸) up the juice.
2. When the bee flies out to work in the morning to look for flowers, it may go to places very far from its hive, but it never loses its way. When the rain comes down, the bee will hide in some little hole in a wall, or perhaps among the leaves of a tree, or inside a large flower.
3.
Bees gather not only the juice but also the pollen(花粉) from inside the flowers.
4. They also use pollen to make wax(蜂蜡).
5. We may also thank it for many useful things which are made of wax.
九年级英语其他题中等难度题查看答案及解析
Spring is here, the colourful flowers are seen everywhere but it is a pity that many of us are not able to smell them while enjoying the colourful flowers.
Growing levels of air pollution from the factories and cars have reduced flower fragrances(芳香) by up to 90 percent in the US, compared with pre-industrial levels 100 years ago.
But if the trend is simply unpleasant for human noses, it may be life-dangerous for bees and butterflies.
Many insects find flowers by following the scent produced by those flowers.
The increasing pollution makes it difficult for them to find the flowers and feed on their nectar (花蜜).
Scientists have already found that flowers produce scent molecules (气味分子) that mix with polluted things, which breaks down the plants’ sweet smell.
With more pollution in the air, the scent molecules don’t remain powerful as long and travel shorter distances on the wind. In the mid-19th century, when pollution levels were first recorded, scent molecules would have been able to travel some 1,000 to 1,200 meters. Today, in the polluted air of large cities, scents may only make it some 200 to 300 meters.
Also, pollution from polluted air may fool the bee’s “nose”, making their search for flowers all the more difficult.
In a paper published recently in Scientific Reports, scientists said that the nitric oxide (NO) and nitrogen dioxide (NO2) in polluted air could change many chemicals that work together to give a flower its special smell.
“This”, researchers said, “could prevent honeybees from reaching their flowers and prevent the pollination (授粉) of some of the world’s food crops.” Or, this could put in danger agricultural harvests worldwide.
But the bees seem to have learned to get used to the changing world. “In nature honeybees use their special eyes and flower smell to find out where a flower is for the first time,” the researchers said.
1.According to the article, researchers have recently found that ________.
A.reduced flower fragrances have resulted in the dying out of many bees and butterflies
B.reduced flower fragrances are connected to growing levels of air pollution
C.polluted things in the air prevent flowers from producing scent molecules
D.flowers today can’t produce enough nectar because of air pollution
2.What do the underlined words “the trend” in Paragraph 3 refer to (指的是)?
A.Increasing air pollution.
B.Reduce flower fragrances.
C.Human beings’ worse sense of smell.
D.A growing number of power plants and cars.
3.The scent molecules a plant produces are mainly to ________.
A.help flowers to produce nectar B.prevent insects from eating the plant
C.draw attention from bees and butterflies D.clear up polluted things in the air
4.We can infer (推断) from the article that ________.
A.future food crops won’t depend on bees to complete their pollination
B.bees have great advantages in their senses compared to humans
C.world food crop production is likely to fall greatly in the near future
D.some bees have successfully get over the challenge of reduced flowers fragrance
九年级英语阅读单选困难题查看答案及解析
— sweet the flowers smell in spring!
—Yes, many tourists come to enjoy them every day.
A. What B. How C. What a D. How a
九年级英语单选题中等难度题查看答案及解析
Trees turn green and flowers come out in _______ spring.
A. the B. a C. /
九年级英语单选题中等难度题查看答案及解析
Spring is coming and there ________ flowers everywhere.
A. is B. are C. was D. were
九年级英语单项填空简单题查看答案及解析