Can plants learn and remember? Monica from Australia thinks so.

    Monica and her team members did some tests on mimosas(含羞草). The plants close their leaves quickly when people touch them. They put some mimosas in 56 pots. Every time they dropped the pots from 30cm high, the plants closed their leaves. Monica and her team members did this for a whole day. To their surprise，at the end of the day, the plants didn't close their leaves at all. It seemed that the plants learned that this action wouldn't hurt them.

    Another amazing thing was that the plants might remember things for a long time. Monica dropped the same pots of mimosas four weeks later. The plants still didn't close their leaves.

    Monica wasn't sure how plants learned and remembered. "The plants don't have brains, after all. Maybe they learn and remember with the help of their cells(细胞)," she said.

    Humans can go to the hospital when they're ill. But as for animals, what should they do？To stay healthy, animals have their own ways to heal(治愈)themselves. Now let's get to know their special skills.

    Skill One

    Have you ever seen your dog or cat lick(舔)its wounds？Why do they do it？It probably feels good, but it's good medicine. Licking cleans a wound, and saliva(唾液)has chemicals that kill germs(细菌).

    Skill Two

    To avoid diseases, many animals have good living habits. They hate to be dirty. Most animals separate their pooping(排便)areas from their eating areas. Horses poop far away from the grass they eat. Rabbits put their poop in special pooping areas.

    Skill Three

    Have you ever heard of the expression "starve a fever(发烧时宜饿)"？Many animals stop eating when they're ill. When a sick animal stops eating, it can stop germs from getting necessary things.

    Skill Four

    Another way that animals heal themselves is to raise their body temperature. High temperature can kill germs. Warm—blooded animals(like us)get fevers to fight with germs.

    Cold—blooded animals(like snakes)look for pieces of wood or rocks heated by the sun.

    Fish move to warmer waters.

    The population of the world is still going up and scientists are worried that there will not enough food for us in the middle of the century. One plant from Madagascar, the Kalanchoe fedtschenkoi, may help. It takes in carbon dioxide (二氧化碳) at night and it needs 10 times less water than food plants like rice. This means it can grow in the desert(沙漠).

    It is dangerous to eat this plant, but scientists can study two things about it: how it takes in carbon dioxide at night when other plants only do this during the day, and why it is so good at living in the desert. There will be less good land for growing food in the future because deserts are increase in size. There, growing plants will be more and more important.

    There is a possible way to take this research. To grow a desert plant to eat will be difficult, but it may be possible to use the genes(基因) from this plant and put them into food plants like beans or potatoes. And the food plants with the genes can grow in the desert. We hope the plant could be an answer to our future food.

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