Career

A doctoral degree is the usual educational requirement to become an astronomer, since most of the work tends to be related to research and development.
Those who opt for this field should clear their plus two examination under the science stream, especially in physics and maths. For pursuing a career in theoretical or observational astronomy one may go through the science stream after plus two. Since universities offering undergraduate program in Astronomy are rarely found, one can join for a major/ honors in Physics with Mathematics as a subsidiary subject. Thereafter, take a master's degree in Physics or Astronomy. After the successful completion of MSc, one can do specialization in astronomy leading to Ph. D. which enables one to become an astronomer/ astronaut/ astrophysicist or a scientist/ research officer etc. in the field of space research.
For doing PhD, which is mandatory to do research, one should appear for the Joint Entrance Screening Test (JEST) examination.

B.Com in Computer Application graduates can find career opportunities in the field of accounting, banking, marketing, e-commerce, teaching, insurance and stock markets. They can work as Probationary officer, Loan officer or Collection officer in various banks. These graduates can also find lucrative jobs in the software industry.
Higher courses you can look for –
Master of Computer Applications
Master of Computer Application in Commerce
Master of Computer Application in Software Systems
Master of Commerce in Computer Applications
Master of Commerce in Finance and Computer Applications
Other certification courses-
Advanced Certification course in Computer Application (ACCA)
Certificate course in Desktop Publishing
Certificate course in Computer Application
Certificate course in Computer Operation and Application (CCOA)

Yes, it is necessary to have knowledge of grad level mathematics if you're going to pursue a degree in biotech. If you're in 12th standard and if it's possible that you can still add a subject in your current curriculum then go for it.
Mathematics is compulsory for admission in government colleges, only private colleges don't have maths as a compulsory. Since you'll be opting for a biotech course (most probably a B.Tech in biotech) then you will require the knowledge of mathematics (grad level).
If you want to improve your maths grade/score then try consulting Math Online Tutor at: https://tutstu.com/tutors/Math/sub/18/COLLEGE
This way you'll be able to prepare for admission exams at your pace and at your own timings.

Bachelor's degree from an accredited institution in engineering, biological science, physical science or mathematics.
At least 1,000 hours pilot-in-command time in jet aircraft. Flight test experience is highly desirable.
Ability to pass a NASA space physical which is similar to a military or civilian flight physical and includes the following specific standards -
Distant visual acuity- 20/100 or better uncorrected, correctable to 20/20 each eye
Blood pressure- 140/90 measured in a sitting position.
Height between 62 and 75 inches
But, if you want to get more detail then please read the given attach files or you can visit the given officials site -
http://www.nasajobs.nasa.gov/astronauts
http://www.jsc.nasa.gov/Bios