My interest in biology dates from my childhood,when I am a young boy, I am always interested in how life-form subsistence in this world , I used to watch ant carrying their food in queue and forgot the time . when it was the time I chose my major in college ,I chose biology without hesitancy . It is no doubt that I love this subject and I wish I could make a career in this field.
Although my major is biotechnology , which doesn’t need much knowledge of mathematics and physics , but I know these two subject play a key role in many field , so , I studied them by myself , such as discrete mathematics and ,When I read some articles of neuroscience , I find that discrete mathematics can be very useful in that . Besides that , I also learn some IT knowledge and get programmer and network engineer certificate in National IT Qualification Test . Maybe these knowledge isn’t so useful , but the skills will be beneficial when I work as a investigator .
When I studied in university , as a sophomore I participated in the program named Using potato starch wastewater to produce GLA with Cunninghamella echinulata,and played a key role in it , in the program , a master and I took charge a small part of it . We looked for the best condition of the fermentation . Temperature , C/N , pH and time should be considered in . We finally got an excellent result and I also learn a lot in this experience , such as how to contribute to a team work , how to deal with the failure of experiments optimistically , etc .
As for my plan of my next five or six years . In fact, I don’t really know . Changes always go beyond plans , and I have not contacted much in Neuroscience or Calculation biology . But I always believe that five years is a very long time , I can learn a lot and do a lot of work in that long time if I study hard . Though foundation is important , I think I can catch up with the students who already have some knowledge or experience in the field through hard working . Now I am reading some treatises and articles about neuroscience . I believe I will know a lot when I get NIBS to attend the interview . I think if I matriculate by NIBS fortunately , I will study in it five or six years , focus on my major (I wish it would be neuroscience.) and get my doctor degree . After that maybe I will go abroad to finish my postdoctoral degree , maybe I will stay in NIBS . But all in all , I want to make some outstanding achievement in biology .
That is all the circumstances about me , I begin to yearn towards NIBS when I was a sophomore . I wish there would be one day I could step into this palace of biology , as a part of it , proudly and confidently . I hope may application will be considered favourably . Thank you !

前段时间我也写了PS,所以有些体会说一下
之前我写了很多修改的地方但是又删掉了，觉得还是总体上说一下比较好：

1、你的语法和用词有很大问题，最好是自己重新检查一下，或者请同学先帮你看看。主要是：1 词汇（hesitation之类）；2 句式（There is no doubt...之类）；句子结构要安排妥当，不要产生歧义;3 语法 （Although 后面不跟but等等）;4 句子组合 英语没有那么多逗号，多用从句，慎用逗号、括号；5 措辞 （尽量少用so, maybe这种口语化的词，改Therefore, I suppose that）；6 时态 （注意统一和准确性）；7、句型多变化，不要老是I开头和主谓宾结构
2、结构安排上来看感觉还可以，只是英语文章每一段的内容都是相互独立的，你文章中用了太多的转折或者自己的猜想，我觉得这会使每一段的中心不明确。

总体感觉问题挺大的，个人建议你重新写一份，或者请专门机构代写一下。