题目内容：

How Plants Branch Out to Access Water

New research has discovered how plant roots sense the availability of water in soil and then adapt (适应)their shape to acquire water. The discovery could enable crops to be raised which are more adaptive to changes in climate conditions, such as the absence of water, and help ensure food safety in the future.

These findings, published in the journal Science, describe a new mechanism(机制) discovered by cooperating teams at the universities of Nottingham and Durham.

Roots are very important for plants to acquire water and nutrients(营养)from the soil. Water is necessary to plant growth , yet changing climatic conditions makes acquiring water from soil even more challenging. Plants are able to adapt to different soil moisture(湿润)conditions by changing their roots.

The researchers discovered that plant roots lacking a branching master gene were no longer able to branch out. They found that when roots have access to moisture, the certain gene remains active and promotes root branching, but when put in air, the gene is in activated, preventing root branching. The research has identified the certain protein which can inactivate root branching.

Professor Sadanandom explained: "This is hugely exciting as it opens up the possibility for us to help develop plants that could continue to branch roots even in challenging conditions such as the absence of water.''

Professor Bennett concluded: "Water is the key to plant growth, development and their survival. By studying how plant roots change their branching in response(回应)to water availability, we have uncovered a new mechanism. This opens the way to develop new crops better adapted to climate change and to help deliver global food safety."

It is absolutely imperative to ensure food safety worldwide. Crop production must double by 2050 to keep pace with global population growth. This target is even more challenging considering the effect of climate change on water availability. In this case, developing crops with better ability to acquire water would provide a solution.

1.The findings of the research may have a positive effect on several global issues EXCEPT

A.ensuring food safety B.preserving the agriculture

C.solving the absence of water D.increasing crop production

2.With the help of the findings, plants may be able to ________.

A.take in more nutrients B.change inactivated roots

C.grow in challenging conditions D.branch out without a special gene.

3.Which of the following best explains “imperative" in the last paragraph?

A.effective. B.hopeful.

C.impractical. D.urgent.

4.What is the new mechanism mentioned by Professor Bennett?

A.How a branching master gene responds to a particular nutrient.

B.How plant roots change their shape according to the soil moisture.

C.Why plants have different abilities to adapt to soil moisture conditions.

D.How the certain protein in activates root branching when accessible to water.