my aim is to become a biomedical scientist?which subject i want take? please guide my career

As you are aspiring to become a biomedical scientists you have to pursue a Bachelor of Science in Biological Sciences, or you may seek a specific undergrad program for biomedical science. You can thing of take foundation classes in chemistry, biology, math and physics. Because research requires strong communication skills, students may also take liberal arts classes in writing and speech.

Below are few additional relevant information i found online...

Types of biomedical scientist
Biomedical scientists usually specialise in one of three areas: infection sciences; blood sciences; or cellular sciences.

Infection sciences include:

clinical microbiology - identification of micro-organisms causing disease and their antibiotic treatment;
virology - identification of viruses, associated diseases and monitoring the effectiveness of vaccines;
immunology - understanding the immune system and its role in combating disease.
Blood sciences include:

clinical chemistry - analysis of body fluids and toxicology studies;
transfusion science - determination of donor/recipient blood compatibility, ensuring blood banks are sufficient;
haematology - form and functions of blood and related diseases.
Cellular sciences include:

histopathology - microscopic examination of diseased tissue samples;
cytology - best known for cervical smear screening, but also covers other cellular analysis;
reproductive sciences - analysis of samples to detect fertility issues.

All the best!