To apply for B.Sc. Biology or B.Sc. Zoology, you must have passed Class 12 with Biology. Admissions are either merit-based (using Class 12 marks) or entrance-based (such as CUET for central universities). You need to visit the official website of the college or university, fill the application form, upload documents, and pay the fee. Based on the merit list or entrance score, attend counselling and confirm your admission.