It provides admission on the basis KVPY, Jee Advanced and State and Central Boards percentage so you will have to clear anyone of them and the syllabus is mentioned below -

Syllabus of Mathematics for IISER Admissions-

Application of Derivatives Applications of integrals Binomial Theorem Complex Numbers and Quadratic equations Conic Sections Continuity and Differentiability Determinants Differential equations Integrals Introduction to Three Dimensional Geometry Inverse Trigonometric Functions Limits and Derivatives Linear Inequalities Linear Programming Mathematical Reasoning Matrices Permutations and Combinations Principle of Mathematical Induction Probability Relations and functions Sequences and Series Sets Statistics Straight Lines Three-dimensional geometry Trigonometric Functions Vector.

Syllabus of Physics for IISER Admissions-

Alternating Current Atoms Behaviour of perfect gas and kinetic energy Communication Systems Current Electricity Dual Nature of Radiation and Matter Electromagnetic Induction Electromagnetic Waves Electronic devices Electrostatics Gravitation Kinematics Laws of Motion Magnetic effect of current and magnetism Motion of Systems of Particles and Rigid body Nuclei Optics Oscillations Physical World and Measurement Properties of bulk matter Thermodynamics Waves Work, Energy and Power.

Syllabus of Chemistry for IISER Admissions -

Some Basic Concept of Chemistry Structure of Atom Classification of Elements and Periodicity in Properties Chemical Bonding and Molecular Structure States of Matter Thermodynamics Equilibrium Redox Reactions Hydrogen s-block Elements p-block Elements Organic Chemistry – Some Basic Principles and Techniques Hydrocarbons Environmental Chemistry The Solid State Solutions Electrochemistry Chemical Kinetics Surface Chemistry General Principles and Processes of Isolation of Elements The d & f-block elements Co-ordination Compounds Haloalkanes and Haloarenes Alcohols, Phenols and Ethers Aldehydes, Ketones and Carboxylic Acids Organic Compounds containing Nitrogens Biomolecules Polymers Chemistry in Everyday Life

Syllabus of Biology for IISER Admissions -

Biology and human welfare Biotechnology and its application Cell structure and function Diversity in the living world Ecology and environment Genetics and evolution Human physiology Plant physiology Reproduction Structural organisation in animals and plants.

And if you talk about cut off then they only release the merit list based on Jee advanced, kvpy and SCB so it is quite difficult to provide any cut off.

Hope this helps!!!