托福official61综合写作生物学类Integrated Writing范文+题目解析

Narrator: Now listen to part of a lecture on the topic you just read about.

Unfortunately, none of the solutions you read about will be very effective in helping to save golden frog populations.

First, using the protective bacterium will probably not work. Scientists introduced to the bacterium to the skin of golden frogs, the bacterium did have a positive effect, but it did not last very long. The protection against the fungus was only temporary. You see, the bacterium produces a chemical that attacks the fungus, unfortunately, the bacterium only produces this chemical early in its colonization of the frog skin. After this brief period, the bacteria stop producing the chemical and therefore stop protecting the golden frogs from the fungal infection.

Second, if we release healthy golden frogs bred in captivity to an area where the wild golden frogs have died out, this new frog population is not going to stay healthy. That's because some other animals living in that environment carry the same disease causing fungus. So if we release golden frogs raised in captivity into that environment, they will soon get infected by the fungus as they come into contact with the wild animals there that are already infected. So this plan probably won't work either.

Third, what about the frogs that defend themselves against the fungus by heating up their bodies? Well, this type of natural defense seems to have a big drawback. Frogs that heat up their bodies have to use up a lot of energy. The expenditure of so much extra energy weakens the frogs and frogs that are weak can easily get ill or even die from other causes. So frogs that use this defense might be protected from the fungus, but they're not strong and healthy. It's unlikely that using this defense will help the golden frog population to recover.