托福official21综合写作生态学类Integrated Writing范文+题目解析

Sure, there are some benefits to plant genetically modified trees, but, are these trees as really great as they first sound? When you examine the subject firstly, there are some serious problems and costs associated with genetically modified trees.First, genetically modified trees may be resistant to one particular condition. But that doesn't necessarily ensure their survival. You see, a typical non modified trees' population is genetically diverse. That means that for most threatening conditions, or climate, insects and other pests, whatever, there will be at least some individual trees of any given species of tree that are resistant. So even if most of one kind of trees are killed, those few resistant trees will survive and ensure the survival of that species of tree. But genetically modified trees are genetically much more uniform. So if they're exposed to an environmental challenge they have not been designed for, they all die. So if the climate changes, the genetically modified trees will likely to be completely wiped out.Now as to the second point, they're hidden costs associated with genetically modified trees. You see, the company that genetically modifies the tree can charge tree farmers more for its seeds than un-genetically modified trees would cost. Also, as you've grown the tree, you can't just collect the seeds and plant the new tree for free. By law, you have to pay the company every time you plant.And finally, genetically modified trees might actually cause even more damage to the local wild trees. You see, genetically modified trees often grow more aggressively than natural trees do. And, genetically modified trees are typically planted among natural trees. As a result, the genetically modified trees outcompete the native trees for resources, sunlight, soil, nutrients, and water, eventually crowding out the natural trees.