Hello there!
Greetings!
Actually,  you don't need to calculate your percentile of biology in neet as it is already mentioned in neet's result,  in the result physics, chemistry and Biology 's percentile scores are written separately and then there's overall percentile as well.
The percentile rank of a score is the percentage of scores in its frequency distribution that are equal to or lower than it. For example, a test score that is greater than 75% of the scores of people taking the test is said to be at the 75th percentile, where 75 is the percentile rank.
Thankyou

Hello there!
Greetings!
You don't need to worry at all regarding this as there's no rule that one needs to appear in neet 2019 to appear in 2020 and there's no need of previous score card at all.
So you can participate in neet 2020 even if you didn't appear in neet 2019.
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Thankyou

Dear Priya, unfortunately there is no short cut to success. Every journey has to go through practise. Even Rome wasn't built in a day and this is Physics we are talking about. Agreed it is a subject that doesnt garner a reader's attention unless you are Sheldon Cooper from the Big Bang Theory. So try watching Physics Videos. You can learn Physics in an interesting way. Lets go through the syllabus first:

The Syllabus for Physics Includes:

Physical World and Measurement
Kinematics
Laws of Motion
Work, Energy and Power
Motion of System of Particles and Rigid body
Gravitation
Properties of Bulk Matter
Thermodynamics
Behaviour of perfect gas and kinetic theory
Oscillation of waves
Electrostatics
Current Electricity
Magnetic effects of current and magnetism
Electromagnetic induction and alternating currents
Electromagnetic waves
Optics
Dual Nature of matter and radiation
Atoms and nuclei
Electronic devices


Best Books:

NCERT Physics Class XI & Class XII
Concepts of Physics by H. C. Verma
Objective Physics By DC Pandey
Fundamentals of Physics by Halliday, Resnick and Walker
Fundamental Physics by Pradeep
Problems in General Physics by IE Irodov

Preparation tips:

Physics needs utmost focus and time because it involves with theoretical concepts and numbers. There should be a systematic approach in preparing for NEET/JEE. The important topics are Mechanics, ElectroDynamics, Modern Physics, Heat and Thermodynamics, Optics, Simple Harmonic Motion, Waves. Formulae form an integral part of your preparation. Memorise as many formulae as you can and write them down and stick them as post its so that you can always see them. Practise regularly and try various kinds of questions. Solving previous papers and mock tests to test your improvement. Keep a clock and check the time its taking you to solve these questions. And improve the time as you practise more. One day of the week should be set aside for revision so as to keep the mind fresh. For reading what the toppers and experts have to say, please visit our page at: https://medicine.careers360.com/articles/how-prepare-for-neet-physics/amp

Dear Sheetal, you will not need to upload any documents durimg filling NEET application form. However, during Counselling one of the documents that you need to bring along is a Disability certificate if availing PWD Benefits. Any disability needs to be first assessed by a team of Doctors at any of the Disability Assessment Centres approved by the MCC. As of now there are 20 such centres and their information is available at mcc.nic.in. You need to produce that certificate for Counselling. Only certificates issued from the Disability Assessment Centres are considered while giving seats under PWD quota.