The motivation letter

Dear people, help meee
I'm an exchange student at the University of Minnesota for one academic year and I'm originaly from Serbia.
Now I want to apply for the Summer school in Munich, and I have to write the motivation letter. would like some of the native speakers to read the letter and say their opinion about it. But I need that as soon as possible, because the dead line is April 30th.

Thanks,

Dusan
Dear,
I wish to apply for the Summer school at the University of Munich, Department of Biology. This summer school would be a concrete step towards my future research carrier in the field of natural sciences.
I'm among the best students of my class. I'm student at the Faculty of Physical Chemistry, University of Belgrade, Serbia. My average GPA was 10.0 (out of 10) in my freshman year. In my first year I applied for the exchange program for one academic year in the US. I got the scholarship, and right now I'm a student at the University of Minnesota. My GPA in the fall semester was 3.79 (out of 4), which put me on the Dean's list of the best students.
Good grades, although important, are not the only indicator of one's research potential. What stands out in my case is the strong confluence among my passion for science and my academic interests. In my high school I participated in the state competitions for chemistry, physics and math with very good results. I was participant at the Center for gifted children Petnica, which gave me a chance to meet a lot of scientists and university students (where I actually decided to study physical chemistry). At the University of Minnesota, I volunteer as a general chemistry discussion section TA, where I help students with general chemistry problems. This section helped me realize how interesting the work with students is, but also how responsible and well prepared one must be for every class.
While I am proud of my academic achievements, I am even more proud of my volunteer work and seminars I attended. In my home town I was part of the Red Cross and the Office of youth. I attended seminars for the youth activism, volunteerism, and nongovernmental organization. These seminars were all over the Europe (Ukraine, France, Greece, and Denmark), so I had chance to travel and meet a lot of young people. On one of them I became the Y-PEER educator for the STD's and protection. Over time, I have assumed the roles of a team member, a time leader, a peer, a junior collaborator. In Serbia I took an active role in the Student Parliament. In the US, I volunteered for the Peace Jam, Big brother - big sister program, Chemists in the Library, etc.
The main reason because of I applied for this school is the multidisciplinary of sciences involved in the research. In the future the scientist will have to be familiar with a variety of subjects, because the emphasis in modern science is on the connection between different branches. Also, the great ranking of the University of Munich, experts who work there, multicultural environment, good equipment are just some of the additional reasons.
I am certain about exceeding all your expectations, may it be academic excellence, motivation for research or interpersonal skills. Furthermore, my international background will definitely add more diversity to your program.
Thank you for considering my application, and I look forward for our future work,
Sincerely yours,