浙江省Z20名校联盟2023届高三第三次联考阅读理解D篇拓展学案

Z20名校联盟2023届高三第三次联考阅读理解D篇拓展练习 一、阅读理解D篇 阅读下列短文，从每题所给的A、B、C和D四个选项中，选出最佳选项。 More than 360 million years ago, during the Devonian(泥盆纪)period, life was flourishing in spectacular fashion. As fish and invertebrates populated the seas, the first trees emerged on land. But by the end of the Devonian, more than half of all Earth's species had disappeared in a series of mass extinctions. New research shows how tree evolution could have contributed to these extinction events. As land plants diversified, “they started to grow more complex root systems that were able to reach farther down to grab water,” says U. S. Naval Academy oceanographer Mathew Smart, lead author of the new study in the Geological Society of American Bulletin. Deep tree roots drew crucial minerals such as phosphorus(磷)out of the bedrock and then eventually decayed, forming mineral-rich soil. Periodically, large quantities of this soil were washed into the seas and lakes-where the sudden phosphorus inflow caused harmful algal blooms(藻华)that pulled oxygen from the waters below. Then came a series of large-scale extinctions. The researchers tracked this deadly pattern in five prehistoric lake beds in Scotland and Greenland. They measured a gradual phosphorus decrease in sediment layers from the middle to late Devonian, accompanied by sudden increase of the mineral with evidence of corresponding oxygen depletion(耗竭). “We've been working on the Devonian for a long time, and we have been thinking that these cycles have occurred, but we couldn't really explain it,” says Anne-Christine Da Silva, a sedimentologist at the University of Liège in Belgium. “This paper could bring an explanation.” University of New Mexico planetary scientist Maya Elrick, who was also not involved in the study, says that while the oxygen depletion incidents coincided with extinctions, it is unclear how much of a role tree roots played. Phosphorus levels did gradually decrease overall as trees evolved, but she says this reduction may