IAT 2026 Important Topics: Every year, the IISER Entrance Exam is conducted to offer admission to the five-year integrated BS–MS dual degree and four-year BS/BTech degree programmes offered by IISERs, IIT Madras, and IISc Bangalore. Thousands of students appear for this exam who wish to pursue a career in science and research.

As the number of seats is limited and registrations are high, the IAT 2026 exam becomes highly competitive. To secure admission to the desired course, a focused and well-informed preparation strategy is essential to achieve an IISER 2026 high score.

One of the most effective ways to plan preparation is by understanding the IAT 2026 important topics, recent exam trends, and chapter-wise weightage across Physics, Chemistry, Mathematics, and Biology.

The SciAstra academic team, based on previous years’ trends and in-depth research, has identified subject-wise high-priority chapters and analysed frequently asked concepts. Studying IAT previous years’ question patterns also helps aspirants understand the difficulty level and nature of questions asked in the exam.

This SciAstra blog provides complete insights into IAT 2026 subject-wise important topics, trend analysis, and chapter-wise weightage, helping candidates streamline their preparation and approach the exam with confidence.

Latest Updates:

IISER 2026 Exam Highlights

Candidates taking the IISER entrance exam for the academic session 2026-2027 can check out the exam highlights from the following details:

Particulars

Details

Exam Name

IISER Aptitude Test (IAT) 2026

Conducting Body

One of the IISER

Exam Level

National Level

Exam Mode

Computer-Based Test (CBT)

Courses Offered

5-year Integrated BS–MS, 4-year BS, and BS–BTech Dual Degree

Participating Institutes

IISERs, IISc Bangalore, IIT Madras (as applicable)

Exam Frequency

Once a year

Medium of Question Paper

English

Subjects Covered

Physics, Chemistry, Mathematics, Biology

Question Type

Multiple Choice Questions (MCQs)

Total Questions

60 (15 questions per subject)

Exam Duration

180 minutes (3 hours)

Marking Scheme

+4 for each correct answer, −1 for each incorrect answer

Total Marks

240

Eligibility

Class 12 (or equivalent) with Science subjects

Selection Process

IAT Score → Counselling → Seat Allotment

Official Website

iiseradmission.in

IAT 2026 Important Topics: Previous Year Trends

The exam officials will assess the candidate’s domain knowledge based on the IISER 2026 syllabus provided by them. Also, in order to get the exam difficulty level and pattern, one should check out the IAT previous year question papers. This will help the candidates in identifying the IAT 2026 important topics and planning an effective preparation strategy.

An analysis of past IAT question papers shows that questions are concept-based, require analytical skills and are evenly distributed across Physics, Chemistry, Mathematics, and Biology.

These recurring trends help candidates prioritise high-scoring chapters and improve accuracy in the IAT 2026 exam. This section will provide details on IAT 2026 subject-wise important topics and previous year trends.

Also Read: How to Prepare for IAT 2026 in Three Months?

IISER 2026 Biology Important Topics and Previous Year Trends

There will be 15 MCQ questions, asked in the examination, with questions designed to test both conceptual clarity and application-based understanding. An analysis of previous years’ IAT papers shows that the topics consistently include Human Physiology, Plant Physiology, and Ecology. Questions from Molecular Biology, Biomolecules, and Biotechnology have also shown a rising trend in recent years.

Check out the previous years trends of the questions from the biology section from here:

Biology

Section

Chapters

2020

2021

2022

2023

2024

2025

Diversity

1

1

1

-

1

1

Morphology and Anatomy

1

2

1

2

1

-

Cell Biology

and Biomolecules

Cell Biology

1

1

1

1

-

1

Biomolecules

-

-

-

2

-

1

Plant Physiology

2

3

2

1

2

2

Human Physiology

3

1

3

1

3

3

Molecular Biology

Genetics

-

-

3

1

1

2

Molecular Biology

1

1

1

1

1

2

Evolution

1

1

1

1

-

-

Human Health

Human Health & Disease

and Microbes in Human Welfare

1

1

-

1

1

-

Reproduction

1

-

-

2

2

1

Biotechnology

1

2

1

1

2

1

Ecology

2

2

1

1

1

1

Also Read: Top IISER in India

IISER 2026 Chemistry Important Topics and Previous Year Trends

Chemistry in the IISER Aptitude Test (IAT) 2026 focuses on conceptual understanding across Physical, Organic, and Inorganic Chemistry. There will be 15 MCQ questions, asked by the exam officials to test candidates’ understanding. Based on previous year trends, the following topics are important and are mainly asked by the officials. Most questions are NCERT-based and require clarity of fundamentals rather than rote memorisation:

Chemistry

Section

Chapters

2020

2021

2022

2023

2024

2025

Physical

Some Basic Concepts of Chemistry

-

-

-

-

-

-

Atomic Structure

1

1

1

1

1

1

Thermodynamics

1

1

1

2

1

1

Equilibrium

-

-

1

-

-

-

Solution

-

-

1

1

1

-

Electrochemistry

1

1

1

-

1

2

Chemical Kinetics

1

2

-

-

1

1

Inorganic

Periodicity

1

-

1

-

1

1

Chemical Bonding

1

3

1

1

2

2

Coordination

2

2

2

-

2

1

d- & f- block

-

-

-

-

-

1

Organic

Introduction To Organic And GOC

-

2

1

2

1

-

Hydrocarbon

1

-

1

1

1

-

Alcohol, Phenol and Ether

-

-

1

-

1

-

Haloalkanes and Haloarenes

-

1

2

1

-

-

Aldehyde, Ketone and Carboxylic Acids

3

2

-

-

-

5

Amines

-

-

1

-

1

-

Biomolecules

1

-

-

1

1

-

IISER 2026 Physics Important Topics and Previous Year Trends

Physics is a high-scoring yet concept-intensive section in the IISER Aptitude Test (IAT) 2026. Analysis of previous year papers shows that questions are primarily numerical and application-based, with a strong focus on fundamentals. Check out the list of important topics that were asked by the officials here:

Physics

Section

Chapters

2020

2021

2022

2023

2024

2025

Mechanics

Kinematics

-

-

-

1

1

-

Laws Of Motion

2

-

-

-

-

2

Work Power Energy

-

-

-

-

-

1

System Of Particles

1

1

2

-

-

-

Rotation

1

2

3

2

2

1

Oscillation

Simple Harmonic Motion

-

1

1

-

3

Waves

-

1

-

1

-

2

Mechanical Properties of Matter

Properties Of Matter

-

-

-

-

-

-

Fluid Mechanics

-

-

1

-

1

-

Kinetic Theory of Gases

1

1

-

-

1

-

Thermodynamics

1

1

1

1

1

-

Gravitation

-

-

-

1

-

-

Electricity

Electrostatics

2

1

2

2

1

1

Capacitors

-

2

1

-

1

-

Current

2

-

-

2

-

1

Electromagnetism

Magnetism

-

-

-

1

1

2

Electromagnetic Induction

1

1

-

1

-

-

Alternating Current

-

-

1

-

1

-

Electromagnetic Wave

1

1

-

-

-

-

Optics

Ray Optics

1

-

1

2

-

2

Wave Optics

-

1

-

-

-

-

Modern Physics

Modern Physics

2

2

2

-

2

3

Semiconductors

-

-

-

1

-

-

Also Read: How Many Times Can You Take the IISER Aptitude Test (IAT)?  

IISER 2026 Mathematics Important Topics and Previous Year Trends

Check out the previous years' trends of the questions from the Mathematics section from here:

Mathematics

Section

Chapters

2020

2021

2022

2023

2024

2025

Algebra

Set Theory

-

-

1

-

-

1

Quadratic Equation

1

-

-

1

-

-

Complex number

-

1

1

-

1

1

Sequence & Series

-

-

-

-

1

1

Binomial Theorem

-

-

-

-

1

1

Matrices & Determinants

2

2

1

1

1

1

Mathematical induction

-

-

-

-

-

-

Differential Calculus

Basic Maths

-

-

-

1

-

-

Relations

-

-

1

-

-

-

Functions

1

1

1

1

1

1

Application of Derivatives

1

-

2

2

1

1

Continuity & Differentiability

1

1

-

1

1

2

Limits

1

1

-

-

-

-

Probability and Statistics

Probability

1

1

1

1

1

1

Statistics

1

1

-

1

-

-

Permutation & Combination

-

-

-

-

-

1

Integral Calculus

Differential Equation

-

-

1

1

1

1

Indefinite & Definite Integral

2

2

2

1

1

1

Area under Curve

2

2

1

1

1

-

Geometry

Straight Lines

1

1

1

1

2

-

Conic Sections

-

-

-

1

-

1

Circles

-

-

1

1

-

-

Vectors

-

-

1

-

1

1

3D geometry

1

1

-

-

1

-

Trigonometry

Trigonometric Equation

-

1

-

-

-

-

IAT Chapter Wise Weightage

The IISER 2026 exam is anticipated to be held in May 2026 in online (CBT) mode to assess candidates’ domain knowledge in Physics, Chemistry, Mathematics, and Biology. As per the IAT 2026 exam pattern, there will be 15 questions from each subject, and candidates will be given a total duration of three hours to attempt the paper.

As the exam is highly competitive, it is crucial for candidates to focus and emphasise on the important chapters of each subject to meet IAT 2026 Cut off. Based on previous year trends, the number of questions asked from each unit or chapter is listed below. Candidates preparing for the exam are advised to give more attention to the topics mentioned.

IAT Biology Chapter Wise Weightage

Candidates can check out the chapter wise weightage of the biology subject from here. Focusing on frequently asked chapters, along with regular practice of NCERT-based questions and diagrams, can significantly boost performance in the IAT Biology section.

IAT Biology Chapter Wise Weightage

IAT Physics Chapter Wise Weightage

Understanding the IAT Physics chapter-wise weightage is essential for effective preparation for the IISER Aptitude Test 2026. Check out the list of chapter from here:

IAT Physics Chapter Wise Weightage

IAT Chemistry Chapter Wise Weightage

Understanding the IAT Chemistry chapter-wise weightage is essential for effective preparation for the IISER Aptitude Test (IAT) 2026. Based on previous years’ question paper analysis, following are chapter wise weighatge analysis of Chemistry subject here:

IAT Chemistry Chapter Wise Weightage

IAT Mathematics Chapter Wise Weightage

Mathematics in the IISER Aptitude Test (IAT) 2026 focuses on logical reasoning, problem-solving skills, and conceptual clarity from the Class 11 and 12 syllabus. Check out the chapter wise weightage distribution of Mathematics subject in IAT previous year exams from here:

IAT Mathematics Chapter Wise Weightage

IISER Exam 2026 Test Series Launched

The SciaAstra team has recently launched a FOCUS test series, which will emphasise Full Online Controlled Understanding and Simulation, helping candidates experience the real-time environment of the IISER aptitude test 2026.

The IAT 2026 FOCUS mock test is designed based on the official exam pattern, and the difficulty level is determined through an in-depth analysis of previous years’ question papers. Candidates will get Unit-wise, Half-length, and Full-length test series, covering all chapters to assess their domain understanding, cognitive skills, and analytical abilities as per the IISER 2026 syllabus.

Attempt the IISER Exam 2026 Test Series to check your exam preparation level to get admissions to the IISERs, IISc and IIT Madras here:

IAT 2026 FOCUS Test Series

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