The University of Massachusetts Medical School, seeking to bolster the number of minority physicians in Massachusetts, plans to offer high school seniors the opportunity to gain admission to college and medical school at the same time. Under the initiative, the state's only public medical school will partner with UMass campuses in Boston, Amherst, Lowell, and Dartmouth to create a joint baccalaureate-MD program that would ensure admission for aspiring doctors from underrepresented ethnic and socioeconomic groups.