I am a 12th commerce student can I admission in biology
Nope! For most colleges, if you need to pursue Biology as a course of study in your UG then you need to have Biology and Chemistry as a subject in your UG. Also there are other subject combination eligible such as Biology and Nutrition but its mandatory to have Biology in 10+2. Now as you didn't have biology in your 10+2 you can't pursue your UG in biology.
To know more about Biology visit the link below:
https://www.careers360.com/courses/biology-course
I hope this answer helps. All the very best for your future endeavors!