GATE and CATB are two separate exams for different purposes.

GATE (Graduate Aptitude Test in Engineering): This exam is primarily for admissions to M.Tech programs in Engineering and Technology disciplines in India. While some universities might consider a GATE score for research programs, it's not widely used for postgraduate studies in Biotechnology abroad.

CATB (Combined Admission Test for Biotechnology): This was an exam conducted by DBT-JNU for admissions to Ph.D. programs in Biotechnology in India. However, the CATB exam is currently discontinued.

For postgraduate studies in Biotechnology abroad, here's what you need:

• Strong Academic Background: A Bachelor's degree in Biotechnology or a related field with good grades is essential.
  
  
• Many universities require standardized tests like GRE (Graduate Record Examinations) or GMAT (Graduate Management Admission Test) for international students.
  
  
• TOEFL (Test of English as a Foreign Language) or IELTS (International English Language Testing System) scores are mandatory to demonstrate your English language skills.
  
  
• A well-written SOP outlining your research interests, goals, and reasons for choosing the program strengthens your application.
  
  
• Strong recommendation letters from professors or research supervisors can significantly enhance your application.
  
  https://engineering.careers360.com/exams/gate
  
  I hope it helps!