初一生物科普作文500字【一】
胞间 连丝：是连接相邻两个植物细胞的跨细胞的细胞器，是植物细胞间物质和信息交流的直接通道，行使水分、营养物质、小信号分子以及大分子的胞间运输功能。
初生纹孔场：初生壁的厚度往往是不均匀的，常有一些凹陷区域，其内有许多胞间连丝通过，这个区域称为初生纹孔场。
纹 孔：次生壁形成时，往往在原有的初生纹孔场处不形成次生壁，这种只有中层和初生壁隔，而没有次生壁的较薄的区域为纹孔。
初一生物科普作文500字【二】
1、分生组织的概念：指植物体内保留的具有持久分裂能力的组织。
2、分生组织组成细胞的特点：细胞壁薄、体积小、原生质浓厚、细胞核大、液泡不明显。
3、分生组织的类型：
按位置分：
1）顶端分生组织分布于根、茎顶端形成初生植物体。
2）侧生分生组织分布于双子叶植物和裸子植物根、茎侧面形成植物体的次生结构。
3）居间分生组织位于植物顶端分生组织被成熟组织隔离而保留下来的部分。
按来源和性质分：
1）原生分生组织直接由植物胚胎里的细胞分裂保留下来的组织。
2）初生分生组织由原分生组织衍生细胞组成，已出现了分化，仍具有分裂能力。
3）次生分生组织由成熟组织经反分化成为具分裂能力的细胞。分为：维管形成层和木栓形成层。
4、组织的形成：成熟组织和非分生组织分生组织衍生的大部分细胞，逐渐丧失分裂能力，进一步生长和分化，形成的其它各种组织。
初一生物科普作文500字【三】
Dear Sir or Madam:
In my capacity as the chairman of Biochemistry and Molecular Biology Department, the School of Life Science, Nankai University, I deem it a pleasure to recommend Mr. Bruce Liu as a worthy candidate for graduate studies at the Department of Cell and Molecular Biology of your esteemed university.
Over the past four years, I delivered two important courses Genetics and Cell Engineering to the Mr. Liu‘s class and his performance was impressive. He is endowed with a strong curiosity in the quest for new knowledge. Before attending each class, he would make full preparations so that he could quickly assimilate what was being taught. Sometimes he could come up with some surprisingly thought-provocative questions and he had a habit of discussing important problems with me in great detail. During those discussions, he often brought with him valuable materials that he obtained from a large quantity of technical literature. Such an initiative enabled him to broaden his ken of knowledge extensively and to cultivate and significantly improve his ability in reading technical literature in English and to follow the latest scientific and technological development in the world. Therefore, even before he graduated, he had already distinguished himself from the rest of his classmates in his English proficiency. Furthermore, his indefatigable spirit of reading large amount of technical materials was not simply intended to secure high scores in his coursework, but more importantly, to satisfy his almost insatiable interest in biology.
Apart from this, I was also very impressed by Mr. Liu‘s hands-on ability in conducting experiments. For many complicated experiments, he undertook them with a rigorous and conscientious attitude and would always complete them satisfactorily. In dealing with crucial steps involved in the experiments, he tended to make bold hypotheses and conduct substantial observations, ultimately achieving remarkable results. All those testify to Mr. Liu‘s tremendous potential in academic research, especially in his analytical skills and in the execution of experimental procedures.
In addition to his scholastic aptitudes, Mr. Liu can be described as trustworthy in personality. His kind-hearted nature and his integrity have created many friends for him. By no means a bookworm, Mr. Liu took an active part in extracurricular activities in which he enhanced his group spirit and the sense of collectivism. His willingness to assist his classmates has brought him a very high reputation.
To summarize, Mr. Liu has been an outstanding student in our department and he is fully qualified to undertake high-level studies in a more challenging environment. His excellent qualities will undoubtedly facilitate him in achieving satisfactory results in his future academic pursuit and in his career.
Yours Sincerely
Professor and Chairman of Biochemistry and Molecular Biology Department
Nankai University
