1. (2020八下·北京月考) 阅读理解

Human, Don't Come Too Close

When we see babies or pets, we can't help gently touching them to show our love. And they give us happy feelings back. But a recent study shows that it's different for plants.

A study, published inThe Plant Journal, shows that plants don't "like" to be touched. That's because touching changes their genes (基因) and, even worse, can slow their growth.

Professor Jim Whelan of the La Trobe Institute in Australia gave an explanation. "The lightest touch from a human, animal, insect, or even plants touching each other in the wind, leads to a huge gene change in the plant,"Science Daily reported.

Frequent touching from humans may change plants' genes and slow their growth.

In order to test the theory, the scientists did an experiment on plants. They grew a number of plants to the age of four weeks. Then they touched them with a paintbrush every 12 hours over a 36-hour period.

They found that as a response to the touch, the mitochondria (线粒体) in the plants had been partly destroyed. The mitochondria, as Science Alert noted, are the "powerhouse of the cell (细胞)". The mitochondria produce energy for the rest of the cell in both animals and plants.

If this "powerhouse" is weakened, the plants will lose a large amount of energy that should have supported their growth. Whelan further explained to Science Daily, "If the touching is repeated, then plant growth is reduced by up to 30 percent."

Although the process does have a strong effect on plants, usually the plants survive. Touching changes the plants, but it's not necessarily a bad change.

According to Science Alert, frequent touching or moving plants will make them grow shorter than other ones. The researchers believe this change, in some way, could be helpful. It may help plants fight threats to their health such as insects and bad weather.

The new research findings have led to a deeper understanding of the plants' response to touching. And the research might "open up new ways to reduce sensitivity (敏感性) and improve growth in the future", Science Alert reported.

1. （1） Why did the scientists do the experiment?

   A . To test if touching can change the genes of plants. B . To show that plants' and animals' genes are different. C . To tell when touching has effect on plants and animals. D . To find out why some plants grow more slowly than others.
3. （2） What did the scientists find in their experiment?

   A . Repeated touching shortened the plants' life by four weeks. B . Touching slowed down plant growth by reducing energy for growth. C . Repeated touching made plants die sooner than they were expected to. D . Mitochondria in the plants couldn't produce energy because of touching.
5. （3） What do the scientists think of the fact that touch makes plants become shorter?

   A . The plants will be more likely to be attracted by insects. B . The plants will be more easily harmed by bad weather. C . The plants will be less sensitive to being touched. D . The plants will be better at fighting dangers.