Sorry to say you, but you can not appear for IIT JEE with PCB Background in 12th, the basic requirements to apply for the IITJEE examination are as following:

Eligibility:
The applicant should have passed their 10+2 examinations from a recognized board with physics ,chem and math with minimum 60% marks.

Age Criteria:
Your age should be in between 17 to 25 years.

I would suggest you to appear in following entrance examinations:

AIIMS - All India Institute of Medical Sciences Entrance Exam
AIPVT - All India Pre Veterinary Test
AIPMT - All India Pre-Medical / Pre-Dental Entrance Examination
AIMS - Amrita Institute of Medical Sciences Entrance Exam
AMUPMDC APGM & APGD CET - AMUPMDC APGM & APGD Combined Entrance Test
AU AIMEE - Annamalai University - All India Medical Entrance Exam
BVP CET - Bharati Vidyapeeth University Combined Entrance Exam
BHU B.Sc Nursing & B. Pharm (Ay.) Entrance Test
BHU PMT - BHU Medical Entrance Exam for M.B.B.S./B.D.S./B.A.M.S./B.Pharm
BLDE UGET - BLDE University Under Graduate Entrance Test
CMC UG AWT - Christian Medical College Ludhiana Entrance Test
CET PPMC - Common Entrance Test for Pondicherry Private Medical Colleges
CPMEE - Common Pre Medical Entrance Exam
COMEDK PGET - Consortium of Medical Engineering and Dental Colleges of Karnataka Post Graduate Entrance Test
COMEDK UGET - Consortium of Medical, Engineering and Dental Colleges of Karnataka Entrance Exam
DMIMS AIPMET - Datta Meghe Institute of Medical Sciences AIPMET
DUSET - Delhi University Super-speciality Entrance Test
DNB CET - Diplomate of National Board Centralised Entrance Test
Dr. D.Y. Patil Institute All India Common Entrance Test for MBBS and BDS
FMGE Screening Test
GPAT - Graduate Pharmacy Aptitude Test
GUJCET - Gujarat Common Entrance Test for MBBS/BDS
HR PMT - Haryana Pre-Medical Test
HDC MDS CET - Himachal Dental College Masters in Dental Surgery Combine Entrance Exam
HP CPMT - Himachal Pradesh Combined Pre Medical Entrance Test
HPTU SLCET for B.Pharmacy - HPTU State Level Common Entrance Test
IVRI - Indian Veterinary Research Institute Entrance Exam
IPU CET Medical - Indraprastha University Common Entrance Test Medical
JNU CEE - Jawaharlal Nehru University Combined Entrance Exam
JSSU UGET - JSS University Under Graduate Entrance Test
KLE UG AIET - KLE University Under Graduate All India Entrance Test
KAIET - Krishna All India Entrance Test
MP DMAT - Madhya Pradesh All India Dental & Medical Admission Test
MP PMT - Madhya Pradesh Pre-Medical Test
MMU CET - Maharishi Markandeshwar University Common Entrance Exam
MGDCH JET - Mahatma Gandhi Dental College and Hospital - Joint Entrance Test
MGIMS - Mahatma Gandhi Institute of Medical Science Entrance Exam
MGMCRI CET - Mahatma Gandhi Medical College and Research Institute Entrance Exam
MGPGI PGDEE - Mahatma Gandhi Postgraduate Institute of Dental Sciences Entrance Exam
Manipal PMT - Manipal Pre Medical Test
AMUPMDC ASSO-CET - Medical Common Entrance Test - ASSO CET - (Maharashtra)
MAHER - Meenakshi Academy of Higher Education and Research Entrance Exam
MMU AIET for M.Sc Nursing - MMU All India Entrane Test for M.Sc Nursing
NBE FEE - National Board of Examinations Fellowship Entrance Examination
NIH BHMS Entrance Exam - National Institute of Homoeopathy BHMS Entrance Exam
NUUGET - Nitte University Under Graduate Entrance Test
PGI MD/MS Entrance Exam - PGI Chandigarh MD/MS Entrance Exam
PIMS AICET PG - Pravara Institute of Medical Science AICET PG
PIMS AICET UG - Pravara Institute of Medical Sciences All India Common Entrance Exam
PPMET - Punjab Para Medical Entrance Test
RPMT - Rajasthan Pre-Medical Test
Rajasthan PC PMT - Rajasthan Private Colleges Pre Medical Test
RD Exam - Registered Dietitian Exam
SRU Medical Entrance Exam - Sri Ramachandra University Medical Entrance Exam for MBBS and BDS
SSAHE AIPGET - Sri Siddhartha Academy of Higher Education AIPGET
SRM Entrance Exam - SRM Institute of Science and Technology Entrance Exam
Sumandeep AICET - Sumandeep Vidyapeeth All India Common Entrance Test
SRH University PMEE - Swami Rama Himalaya University Pre Medical Entrance Exam
UPCMET - Uttar Pradesh Combined Medical Entrance Test
UP CPMT - Uttar Pradesh Combined Pre Medical Test
UPCAT - Uttar Pradesh Common Admission Test
UPMT - Uttaranchal Pre-Medical Test
VMU AICEE - Vinayaka Missions University All India Common Entrance Exam