phd in political science

<p>hello everyone..first i want to thank you for your time in posting answers.
i have to questions that i hope u can help me with..
is it very common for people to go from a BA to a phd program in political science, and to do that what is it research experience primary?
second question, i have a poor GPA first two years of college and a solid GPA my last two years (3.1 first two years, and 3.8 last two) the reason is that I got 4 Cs in math and science which was required in my program.
will that hurt my application, if i decided to apply to top schools?would i have any chances</p>

<p>and plus i am an intl student,so i do not know what pool of applicants i would be in.
thanks everyone!!!</p>