2013年5月26日托福考试真题分享——阅读部分
第一篇 TOPIC：Cell-theory 细胞理论 第一段：科学家Robert Hooke在1665年运用"单片镜"看到细胞的轮廓，Hooke用"单片镜"观察细胞轮廓比当时的"双片镜"更有优势（细节题，为什么用"单片镜"观察）。Hooke的历史地位在于他是看到"细胞"的第一人，并给这种结构命名为"cell",现在一直沿用，但是缺陷在于看到的只是"死细胞"--细胞死后的细胞壁留下的轮廓。 第二段：Anton van Leeuwenhoek第一次看到了活细胞，是从他的牙龈上刮下来细菌（bacteria）。但是他没有挑战错误的"传统理论"：生命从"无生命形式"发展而来（cell evolves from nonliving form and nothingness）。同样错误的理论是：完整的细胞可由Nucleus (细胞核)生长出membrane(细胞膜)和细胞壁。细胞难以被观察到有两大原因：1，技术不够成熟（technology）;2. 错误理论的根深蒂固。 第三段：Theodor Schwann和Matthias Jakob Schleiden进一步观察细胞。他们共同观察了"动物"和"植物"的细胞，并得出细胞是""The cell is the fundamental element of organization，unit of structure and function"。Schleiden在显微镜（microscope）下观察到兰花植物（orchid plant）细胞,并在显微镜下也观察到其他动物细胞。两位科学家的共同结论是：细胞(cell)可以单独存在（existed）,但是在更大的器官中（larger organisms）是living organism的一部分（这句话是"重述题"）。他们共同确定了细胞理论。 第四段：英国科学家Robert Brown 完善了细胞理论，并成为细胞理论的先驱者。他的瞻前发现是：很多疾病（diseases）是从一个变异细胞（abnormal cell）演变而来，这在当时并没有被接纳，但是现代理论证明这是正确的。 解析：本文话题属于生物学中的微生物学，从话题角度在TPO中并无直接对应篇章；本文结构为理论的诞生与发展，从结构角度在TPO中与The Birth of Photography, Transition to Sound in Film等文章很相似。此类文章重点是理清不同的理论观点背后的文章脉络。 Cell theory The cell was first seen by Robert Hooke in 1665. He examined (under a coarse, compound microscope) very thin slices of cork and saw a multitude of tiny pores that he remarked looked like the walled compartments a monk would live in. Because of this association, Hooke called them cells, the name they still bear. However, Hooke did not know their real structure or function. Hooke's description of these cells (which were actually non-living cell walls) was published in Micrographia. His cell observations gave no indication of the nucleus and other organelles found in most living cells. The first person to make a compound microscope was Zacharias Jansen, while the first to witness a live cell under a microscope was Anton van Leeuwenhoek, who in 1674 described the algae Spirogyra and named the moving organisms animalcules, meaning "little animals". Leeuwenhoek probably also saw bacteria. Cell theory was in contrast to the vitalism theories proposed before the discovery of cells. The idea that cells were separable into individual units was proposed by Ludolph Christian Treviranus and Johann Jacob Paul Moldenhawer. All of this finally led to Henri Dutrochet formulating one of the fundamental tenets of modern cell theory by declaring that "The cell is the fundamental element of organization". The observations of Hooke, Leeuwenhoek, Schleiden, Schwann, Virchow, and others led to the development of the cell theory. The cell theory is a widely accepted explanation of the relationship between cells and living things. The cell theory states: All living things or organisms are made of cells and their products. New cells are created by old cells dividing into two. Cells are the basic building units of life. The cell theory holds true for all living things, no matter how big or small. Since according to research, cells are common to all living things, they can provide information about all life. And because all cells come from other cells, scientists can study cells to learn about growth, reproduction, and all other functions that living things perform. By learning about cells and how they function, you can learn about all types of living things. Cells are the building blocks of life Credit for developing cell theory is usually given to three scientists: Theodor Schwann, Matthias Jakob Schleiden, and Rudolf Virchow. In 1839, Schwann and Schleiden suggested that cells were the basic unit of life. Their theory accepted the first two tenets of modern cell theory (see next section, below). However, the cell theory of Schleiden differed from modern cell theory in that it proposed a method of spontaneous crystallization that he called "free cell formation". In 1855, Rudolf Virchow concluded that all cells come from pre-existing cells, thus completing the classical cell theory. (Note that the idea that all cells come from pre-existing cells had in fact already been proposed by Robert Remak; it has been suggested that Virchow plagiarised Remak.)
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发表于 2015-8-18 11:24:32
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