So, if you get the first question right, the second question should be a little harder and if you get the first question wrong, the second question should be a little easier, and so on.
Harder questions generate higher scores and easier questions lower scores.
The earlier questions of a GMAT CAT section are crucial in determining your baseline score, so invest the necessary time to try and answer these questions correctly. You must, however, pace yourself so that you have time to mark an answer for every question in the section. Don't over invest.