往年托福对于生物学的考察常常有规律可行，文章涉及内容较表观，紧扣animal characteristics, behavior and evolution三大方向，解题并不难。但近年来，托福听力文章趋于描述微观机理，探查机理过程中所用的技术，以及某些发现对于发明新的科学技术的启示，出题较为细节化。

真核细胞： Eukaryotic cells

Figure 1. Structures of an animal cell

（Adapted from the image on the website: https://www.yourgenome.org/facts/what-is-a-cell）

参见: TPO 18 L4 （讲到北美树蛙如何freeze themselves at cellular level）

TPO 45 L2 ( T –CELL, human immune system)

知识小贴士：

Cell membrane: Every cell in the body is enclosed by a cell membrane. The cell membrane separates the material outside the cell, extracellular, from the material inside the cell, intracellular. 

Cytoplasm: The cytoplasm is the gel-like fluid inside the cell. It is the medium for chemical reaction. It provides a platform upon which other organelles can operate within the cell.

Organelles: Cytoplasmic organelles (细胞器) are "little organs" that are suspended in the cytoplasm of the cell. Each type of organelle has a definite structure and a specific role in the function of the cell. E.g. Mitochondria（线粒体）is where respiration occurs.

Figure 2. Structures of a plant cell

参见：TPO19L3（spartina能够生活在salt marsh中是因为reverse osmosis 作用）

TPO43L1 （讲到叶绿素）

知识小贴士：

Cell wall: a rigid layer of polysaccharides (多糖) lying outside the plasma membrane of the cells of plants, fungi, and bacteria. In the algae and higher plants, it consists mainly of cellulose （纤维素）and chitin (几丁质).

Figure 3. Filamentous Fungi

参见： TPO42L3 ( 真菌细胞壁的几丁质具有吸附土壤中的重金属的作用)

Cells are the structural and functional units of all living things. They can further group together to form tissues, and finally function as organs.

原核细胞： Prokaryotic cells

Figure 4. Bacteria ( adapted from the image on the website: https://leavingbio.net/bacteria%20page.htm)

参见：  TPO15L4 (Biocommunity)

新托福真经4  P142 Microbiology

知识小贴士： 细菌是导致人体疾病的病原体（pathogen）之一， 抗生素（antibiotics）比如说青霉素penicillin是治疗细菌性感染（infection）的常用药物。由于抗生素的滥用，细菌逐渐产生了对抗生素的抗性（resistance），因此，在美国抗生素是处方药（prescribed medicine）.而科学家研发新型抗生素的速度远远赶不上细菌变异的速度。感染性疾病无药可治将是人们即将面对的困境。

DNA- RNA-蛋白质

Figure 5. 遗传物质到蛋白质的转换（adapted from the image on the website: https://cancergrace.org/cancer-101/tag/dna/）

参见： TPO5L1 ( Meme)

       TPO10L1 (Whales)

       TPO12L1 ( Cell division)

       TPO30L3（Life on Mars）

       TPO33L3 (Notothenioids)

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