Hello dear.. As you are interested in Medical field you can pursue MD Psychiatry after your MBBS. But if you want to do B.A or B.Sc psychology,  admission norms are different for different Colleges/Universities. some universities release cutoff on the basis of marks obtained in 10+2 or intermediate,  whearas some University conducted it's own entrance exam for admission screening such as Banaras Hindu University, Jamia Milia Islamia etc. So there is no fixed qualifying examination to appear in graduation, it vary from College to College. You can apply according to your preference.

Hope it helps.

Good Luck.