Botany

Yes, if you choose to major in microbiology, you can also become a lecturer in Zoology or Botany. To qualify for lectureships, you must first complete a master's degree in microbiology before applying for exams like the CSIR NET. You can be chosen for a lectureship and a Junior Research Fellowship through the CSIR NET Exam, which is administered by the NTA (National Testing Agency). Only candidates from the Science stream are eligible to take this exam. The subjects covered by this exam include:
Natural Science
Molecular Science
Life Science Mathematical Science
Planetary Science
You must submit a CSIR NET Life Sciences application because you are studying microbiology. The administrators will issue you a Certificate once you pass the test, which you can use to apply for assistant professor positions at various colleges and universities.

No, you cannot get admission for M.Sc computer Science after your B.Sc (zoology/ botany /Chemistry). This is because, The general eligibility criteria to be eligible for M.Sc computer Science is that you should have a Bachelor's or graduate in
-) Computer Science
-)Computer Applications, -)Mathematics
-) degree in Science discipline with Maths in at least 4 semesters. For example, Central University of Tamil Nadu, Thiruvarur eligibility criteria is given below:-
To be eligible you must a degree in Computer Applications or Computer Science or Mathematics/ or any degree in Science with Mathematics as in at least 4 semesters. And you must have secured at least 60% marks or 6.5 CGPA your degree examination, 55% marks or 6.0 CGPA for OBC and 50% marks or 5.5 CGPA for SC/ST candidates.