Hello Aspirant,

See NEET consists of syllabus of class 11th and 12th both and there is nothing a kind of important because any question might be asked from any topic but yes there are some topics which have higher weightage as compared to others and on the basis of same weightage we consider them like important. So for NEET , complete chapter wise weightage for each subject is described below and topics with more weightage can be considered as important  :-

@Physics

Physical-world and measurement-2%

Kinematics-3%

Laws of Motion-3%

Work, Energy and Power-4%

Motion of System of Particles and Rigid Body-5%

Gravitation-2%

Properties of Bulk Matter-3%

Thermodynamics-9%

Behaviour of Perfect Gas and Kinetic Theory-3%

Oscillation & Waves-3%

Electrostatics-9%

Current Electricity-8%

Magnetic Effect of Current & Magnetism-5%

Electromagnetic Induction & Alternating Current-8%

Electromagnetic Waves-5%

Optics-10%

Dual Nature of Matter and Radiation-6%

Atoms & Nuclei-3%

Electronic Devices-9%

@Chemistry

Basic Concepts of Chemistry-1%

Structure of Atom-2%

Classification of Elements & Periodicity in Properties-2%

Chemical Bonding and Molecular Structure-5%

States of Matter: Gases and Liquids-2%

Thermodynamics-8%

Equilibrium-6%

Redox Reactions-3%

s-Block Elements-2%

Some p-Block Elements-2%

Organic Chemistry: Basic Principles & Techniques-4%

Hydrocarbons-3%

Environmental Chemistry-2%

Solid State-2%

Solutions-5%

Electrochemistry-2%

Chemical Kinetics-3%

Surface Chemistry-2%

Isolation of Elements-2%

p-Block Elements-5%

d- and f-Block Elements-4%

Coordination Compounds-9%

Haloalkanes and Haloarenes-3%

Alcohols, Phenols and Ethers-4%

Aldehydes, Ketones and Carboxylic Acids-4%

Organic Compounds containing Nitrogen-2%

Biomolecules-3%

Polymers-3%

Chemistry in Everyday Life-2%

@Biology

Diversity of Living Organisms-14%

Structural Organisation in Plants & Animals-5%

Cell: Structure and Function-9%

Plant Physiology-6%

Human Physiology-20%

Reproduction-9%

Genetics and Evolution-18%

Biology and Human Welfare-9%

Biotechnology and its Applications-4%

Ecology and Environment-6%

For complete details about important chapters and other weightage related information kindly check out the links given below :-

https://medicine.careers360.com/articles/neet-chapter-wise-weightage-and-important-topics

You can also check out NEET Knockout package for your preparation :-

https://learn.careers360.com/knockout-neet-may/?product=50&icn=knockout-neet-2021-may&ici=

I hope this information helps you.

Good Luck!!