Explain how class acts as an obstacle for characters that have ambitions in life?

In an environment where class distinctions flourish, one is never expected to try to rise above one's "station."  Therefore, ambition is of little value because people in higher classes do not want to see anyone rise out of his/her class.  This becomes an obstacle since those above may actually throw roadblocks in the path of someone who tries to rise from a lower class.

 Is it the same in Pride and Prejudice?
When class acts as an obstacle for characters that have ambitions in life.

Thank you.