生物作文2500字【一】
1、植物细胞的生长中细胞体积和重量不可逆的增加。
2、原生质生长和细胞壁生长。
生物作文2500字【二】
1：细胞周期：一次细胞分裂中期到下一次分裂中期的全部历程。包括：分裂间期和分裂期两个阶段。
2：分裂间期：前一次分裂结束到下一次分裂开始的一段时间。包括：复制前期、复制期和复制后期。
3：细胞分裂的三种形式：有丝分裂，减数分裂，无丝分裂。
4：有丝分裂：
特点：1）多数发生在植物体细胞中。
2）两个过程：一是核分裂，二是胞质分裂。
3）分裂后形成两个新的完整的细胞，与原细胞相同。主要作用是生长发
育和新陈代谢 。
5：减数分裂：
特点：1）与有性生殖有关，多数发生在性细胞中，分裂后产生生殖细胞。
2）细胞连续分裂两次;DNA复制一次。
3）一个母细胞分裂两次产生4个子细胞。
4）染色体数目减半。
生物作文2500字【三】
一层液泡膜包被，其中充满细胞液，液泡占据成熟细胞的大部分体积。
成分： 是水，还含有盐、糖、可溶性物质、晶体等。
功能： 维持细胞的膨压；细胞代谢产物的贮藏场所
生物作文2500字【四】
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
