1 . For many people, catching a smell of freshly cut grass is a pleasant sign that warmer weather is here to stay. For the grass, however, this scent signals an entirely different story.
The smell we associate with freshly cut grass is actually a chemical SOS, one used by plants to beg nearby creatures to save them from attack. After all, when danger strikes —whether it's gardening equipment or a hungry caterpillar — plants can't lift their roots and run. They must fight where they stand. To protect themselves, plants employ a string of molecular (分子) responses. These chemical communications can be used to poison an enemy, warn surrounding plants of dangers or attract helpful insects to perform needed services.
Clearly, plants can communicate. But does that mean they can feel pain? According to some researchers, plants release gases that are the equivalent of crying out in pain. Using a laser-powered microphone, researchers have picked up sound waves produced by plants releasing gases when cut or injured. Although not audible to the human ear, the secret voices of plants have revealed that cucumbers scream when they are sick, and flowers cry when their leaves are cut.
There's also evidence that plants can hear themselves being eaten. Researches show that plants understand and respond to chewing sounds made by caterpillars dining on them. As soon as the plants hear the noises, they respond with several defense mechanisms.
For some researchers, evidence of these complex communication systems — giving out noises via gas when in pain — signals that plants feel pain. Others argue that there cannot be pain without a brain to register the feeling. Still more scientists infer that plants can exhibit intelligent behavior without possessing a brain or conscious awareness.
As they grow, plants can change their paths to avoid obstacles or reach for support with their tendrils (卷须). This activity comes from a complex biological network distributed through the plants' roots, leaves and stems. This network helps plants reproduce, grow and survive.
1. What does the smell of freshly cut grass signal?| A．Warmer weather. | B．Being poisonous. |
| C．Cry for help. | D．The need of services. |
| A．By giving out gases. | B．By changing the color of their leaves. |
| C．By producing audible sound waves. | D．By sharing it through the root systems. |
| A．Their tendrils. | B．Their biological network. |
| C．Their communication systems. | D．Their conscious awareness. |
| A．Do plants feel pain? | B．How plants protect themselves? |
| C．Do plants communicate? | D．How plants grow and reproduce? |
