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(有绒毛的)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(紧紧抓住)the soil.
The hairs are guided by a clever chemical trick. A protein(蛋白质) at the tip of the root hairs called RHD2 helps them to take calcium(钙) 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(栽培变种) are developed.”
【小题1】The passage is mainly about _______.

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(有绒毛的)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(紧紧抓住)the soil.

The hairs are guided by a clever chemical trick. A protein(蛋白质) at the tip of the root hairs called RHD2 helps them to take calcium(钙) 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(栽培变种) are developed.”

1.The passage is mainly about _______.

2.How does the circle work?

3.We can infer from the last paragraph that ________.

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(有绒毛的)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(紧紧抓住)the soil.
The hairs are guided by a clever chemical trick. A protein(蛋白质) at the tip of the root hairs called RHD2 helps them to take calcium(钙) 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(栽培变种) are developed.”

1. 1.

   The passage is mainly about _______.

   1. A.
      why the roots of plants grow into the soil but not above it
   2. B.
      how the roots of plants grow into the soil but not above it
   3. C.
      the process of plants growth
   4. D.
      a growth control system of plants
2. 2.

   How does the circle work?

   1. A.
      RHD2 takes calcium from the soil, which makes hairs grow, and produce RHD2 and take more calcium
   2. B.
      Roots take RHD2 and calcium from the soil and produce RHD2
   3. C.
      Roots make hairs grow, and produce RHD2, and take more calcium
   4. D.
      RHD2 takes protein, which makes hairs grow, and produce RHD2, and take more calcium
3. 3.

   We can infer from the last paragraph that ________.

   1. A.
      hairy rooted crops can grow better in unfriendly environments
   2. B.
      a new cultivar of wheat with long hair has been developed by scientists
   3. C.
      a new cultivar of wheat with long hair is still on test
   4. D.
      the roots of plants always know which way to grow

The beet (甜菜) is a tasty root vegetable that does not require much work to grow. People think of beets as being always dark red，but they can also be pink，yellow or white. Beets are high in nutrients，and both the root and the tops can be eaten. The leaves make good salads when the plants are young，and the greens can be cooked when the plants are older. Beets grow best in full sun and in loose soil that is not too wet.
Remove stones from the soil while preparing the ground，and test it before adding fertilizer Beet seeds can be planted as soon as the soil can be worked at the start of the growing season. Planting them every two or three weeks will provide a continuous harvest into the fall. A beet seed is a fruit containing several seeds. Overcrowding the plants will mean that the roots cannot spread out and grow，so thin the beets by removing the smaller ones and using them as greens.
A specialist named Cindy Haynes says little or no fertilizer is needed in rich soils. Once the seeds are planted，however，she suggests covering the soil to protect it from the rain and during dry periods. She also suggests putting a fence around the plants to keep away rabbits and deer. She says the only work beets need once they have been thinned is weeding and， when the weather is dry，a weekly watering. For best results，beets should be picked when the roots are two and one-half centimeters around. Larger beets can be tough，and have to be cooked for a long time. Beets can be eaten in many ways.
60.What is the second paragraph mainly about?
A. How to test the soil.           B. How to plant beets
C. When to harvest beets.          D. When to plant beets.
61.Smaller beets are often removed in order to       .
A. give other beets space to grow    B. add more fertilizer to the soil
C. plant new seeds                D. use the green，young leaves in salads
62.What may the next part of the last paragraph be about?
A. When to pick beets.             B. How to eat beets.
C. The uses of beets.              D. The taste of larger beets.
63.The passage is most probably from a(n)     .
A. gardening book   B. education magazine   C. science report   D. entertainment magazine

The beet (甜菜) is a tasty root vegetable that does not require much work to grow. People think of beets as being always dark red，but they can also be pink，yellow or white. Beets are high in nutrients，and both the root and the tops can be eaten. The leaves make good salads when the plants are young，and the greens can be cooked when the plants are older. Beets grow best in full sun and in loose soil that is not too wet.

Remove stones from the soil while preparing the ground，and test it before adding fertilizer Beet seeds can be planted as soon as the soil can be worked at the start of the growing season. Planting them every two or three weeks will provide a continuous harvest into the fall. A beet seed is a fruit containing several seeds. Overcrowding the plants will mean that the roots cannot spread out and grow，so thin the beets by removing the smaller ones and using them as greens.

A specialist named Cindy Haynes says little or no fertilizer is needed in rich soils. Once the seeds are planted，however，she suggests covering the soil to protect it from the rain and during dry periods. She also suggests putting a fence around the plants to keep away rabbits and deer. She says the only work beets need once they have been thinned is weeding and， when the weather is dry，a weekly watering. For best results，beets should be picked when the roots are two and one-half centimeters around. Larger beets can be tough，and have to be cooked for a long time. Beets can be eaten in many ways.

60.What is the second paragraph mainly about?

A. How to test the soil.           B. How to plant beets

C. When to harvest beets.          D. When to plant beets.

61.Smaller beets are often removed in order to       .

A. give other beets space to grow    B. add more fertilizer to the soil

C. plant new seeds                D. use the green，young leaves in salads

62.What may the next part of the last paragraph be about?

A. When to pick beets.             B. How to eat beets.

C. The uses of beets.              D. The taste of larger beets.

63.The passage is most probably from a(n)     .

A. gardening book   B. education magazine   C. science report   D. entertainment magazine