Can I appear for both the Software Systems and Electronics papers? Is it allowed?

Only in the case where you have been selected on the basis of GPAT route, will you be entitled to the GPAT scholarship even though you might also qualify based on the BITS HD test.

GPAT Scholarship Eligibility at BITS Pilani (M.Pharm / M.Pharm + MBA):

This is how it looks like in a nutshell:
The benefits of GPAT Scholarship
Rs. 12,400 as twenty-four months (M.Pharm) monthly stipend.

Not offered by BITS Pilani itself, but by AICTE.

You should not be a worker or a recipient of any other significant scholarship.

Valuable Remarks
At admission time, you need to choose from GPAT based admission (and not BITS HD score) in order to get GPAT stipend.

When you get admission under BITS HD only, even though you are qualified to sit in GPAT you will not be offered stipend by AICTE.

You need to make sure that in your admission offer of BITS the route of qualification as GPAT is mentioned so that you will avail the scholarship.

 Recommendation
So, in case you want to study based on the GPAT scholarship, then:

Get in via the GPAT route.

In the course of document verification or online admission, make sure that your GPAT information is provided and accepted.

Yes, a B.Sc. Biotechnology student can appear for the BITS HD (Higher Degree) admission test. BITS HD programs are designed for those who have completed a bachelor's degree, including those in Biotechnology. A B.Sc. in Biotechnology is a valid entry point for several BITS HD programs, particularly in fields related to Biotechnology. 

Eligibility:

For BITS HD in Biotechnology:

A B.Sc. in Biotechnology is a direct pathway to the M.E. or M.Sc. programs in Biotechnology offered by BITS. 

For other BITS HD programs:

You may need to consider programs that require related disciplines or specific prior preparation, as outlined in the BITS admission brochure. 

General BITS HD requirements:

BITS HD programs generally require candidates to have completed a bachelor's degree (or equivalent) and to meet specific eligibility criteria for the programme they are applying for, including a minimum score in the BITS HD entrance test or other qualifying exams. 

Steps to apply:

1. Check BITS HD brochure:

Review the BITS HD brochure for the specific programme you are interested in, as it outlines the eligibility criteria, required documents, and admission process, available on BITS website. 

2. Prepare for the BITS HD entrance test:

Familiarize yourself with the BITS HD exam syllabus and pattern, and prepare accordingly. 

3. Submit application:

Complete the BITS HD application form, including all required documents, and submit it before the deadline, as detailed in the brochure. 

4. Appear for the test:

Attend the BITS HD entrance test on the scheduled date. 

5. Check results and admission:

Once the results are released, check for admission based on your score and other criteria, as outlined in the BITS admission brochure.

The ME disciplines that are available for BITS HD counselling and seat allotment are mentioned below. The seat allotment will be based on the performance of the candidate in the exam. 

•  Biotechnology
• Chemical Engineering
• Civil Engineering in Infrastructure Engineering and Management
• Civil Engineering in Structural Engineering
• Civil Engineering in Transportation Engineering
• Communication Engineering
• Mechanical Engineering
• Design Engineering
• Embedded Systems
• Environmental Engineering
• Software Systems
• Manufacturing systems engineering, and 
• Computer Science

Courses will be offered to candidates for Pilani, Goa, and Hyderabad campuses.