GATE

If you want to become a scientist at ISRO, you should appear for the ISRO qualifying exam rather than appear for GATE.
The eligibility:
BE/B.Tech or equivalent qualification in first class with an aggregate minimum of 65% marks or CGPA 6.84/10 (average of all semesters for which results are available). Minimum of 65% marks or CGPA 6.84 in section B alone for candidates with AMIE/Grad IETE qualification.
The qualification prescribed and the benchmark are only the minimum requirement and fulfilling the same does not automatically make candidates eligible for written test.
To answer your question, GATE syllabus for both would be the same.

Hello Kuldeep,
No, you cannot. You need to have a M.Sc degree after B.Sc to become eligible for GATE exam.
Only BE/B.Tech graduates are directly eligible for GATE exam.

Hello Shivani,
No, you cannot. The eligibility to appear for GATE for a B.Sc student is to have an M.Sc degree.
Only BE/B.Tech and B.Arch students are directly eligible without post graduate degree.
All the best!

Microelectronic circuits: Theory and application.

GATE score is valid for 3 years. GATE score is not required for seeking admission in part-time or distance learning M.Tech.

Hello Sanjay,
GATE exam is only for admission into post graduate programs in the top Institutes like IIsc, IITs, etc.
To get government jobs you need to appear for the respective exams satisfying the eligibility requirements.