Yes, a change is possible especially if they is a large overlap in classes. My friends daughter was admitted to UCI last year and wanted to change her major from Biochem to Bio. She went to Freshman orientation and sat down with the Bio advisor along with the Biochem advisor and worked out her schedule so after 2 quarters with good grades, she could offically change her major. Again, there was a lot of overlap in the pre-req classes between the two majors. Good Luck.