GATE Life Sciences Syllabus 2027: XL0 to XL5 Guide

The GATE Life Sciences syllabus for 2027 covers General Aptitude, compulsory Chemistry (XL0) and five optional subjects, of which you attempt any two. IIT Madras, which organises GATE 2027, has published a separate syllabus PDF for each section, and the syllabi were revised for this cycle. This page organises those official topic lists into a study checklist.

Use it to see what each section asks, decide which two optional subjects suit you and plan your order of study. The official PDFs remain the final word, so keep them open while you prepare.

Table of Contents

• GATE Life Sciences syllabus at a glance

• Key changes to know

• XL0 Chemistry syllabus

• Optional subject syllabus: XL1 to XL5

• General Aptitude syllabus

• Overlap between subjects

• How to cover the syllabus

GATE Life Sciences syllabus at a glance

The total is 100 marks: 15 for General Aptitude, 25 for XL0 and 60 for the two optional sections. Question counts for each section are not published, so the marks above are the only reliable weightage. Format, timing and negative marking are on our GATE Life Sciences exam pattern page.

Key changes to know

• New section codes: the sections are now XL0 to XL5. In GATE 2026 they were labelled P to U, and many older notes still use those letters.

• Revised syllabi: the organisers state the syllabi were revised for GATE 2027. Topics in the XL syllabus PDFs, such as genome editing in Botany, next-generation sequencing in Biochemistry and non-thermal processing in Food Technology, are worth checking against your old notes.

• Official source: the syllabus PDFs sit on the official test papers and syllabus page. Older pages may still show the earlier syllabus, so follow the official 2027 files.

XL0 Chemistry syllabus (compulsory)

Chemistry carries 25 marks for every XL candidate, and its topics lean towards physical and organic chemistry with a biological angle. Start with the sections that connect to biochemistry, because they also help your optional subjects.

Optional subject syllabus: XL1 to XL5

You attempt any two of the five subjects below, each for 30 marks. The lists summarise the official section headings and their main topics.

XL1 Biochemistry

• Biomolecules (XL1.1): carbohydrates, lipids, proteins and nucleic acids; protein structure, folding and misfolding; selected model proteins and enzymes.

• Enzymes and metabolism (XL1.2): catalysis, kinetics up to two substrates, inhibitors, regulatory enzymes, vitamins and coenzymes, ATP, hormonal regulation.

• Metabolic pathways (XL1.3): glycolysis, TCA cycle, pentose phosphate pathway, oxidative phosphorylation, gluconeogenesis, fatty acid and nitrogen metabolism, photosynthesis, metabolic disorders.

• Analytical techniques (XL1.4): buffers, chromatography, centrifugation, electrophoresis, spectroscopy, PCR, sequencing, immunological techniques, monoclonal antibodies.

• Cell structure and function (XL1.5): organelles, membranes, transport, protein targeting, biosignalling, ion channels.

• Gene expression and DNA repair (XL1.6): replication, transcription, translation, DNA damage and repair, regulation of expression.

XL2 Botany

• Plant systematics (XL2.1): nomenclature, classification, APG system, major families, phylogenetics, DNA barcoding.

• Plant anatomy (XL2.2): root, stem and leaf anatomy, meristems, vascular system, secondary growth.

• Plant development (XL2.3): angiosperm life cycle, gametophytes, embryogenesis, apical meristems, flowering, photomorphogenesis, plant hormones.

• Physiology and biochemistry (XL2.4): water relations, photosynthesis, respiration, abiotic stress, secondary metabolites, hormone biosynthesis and action.

• Genetics and genomics (XL2.5): Mendelian inheritance, linkage, epigenetics, gene silencing, genome organisation, omics, bioinformatics.

• Breeding and genetic modification (XL2.6): breeding methods, markers, tissue culture, transgenics, CRISPR/Cas9, Cre-Lox.

• Economic botany (XL2.7), plant pathology (XL2.8) and ecology (XL2.9): economically important plants, crop diseases and resistance, plant-microbe interaction, ecosystems, biodiversity and climate change.

XL3 Microbiology

• Foundations (XL3.1 to XL3.3): historical perspective, pure culture, sterilisation, microscopy, PCR, taxonomy of bacteria, archaea, yeasts, moulds, protozoa and viruses.

• Cell and growth (XL3.4 and XL3.5): prokaryotic cell structure, transport, motility, growth curve, continuous culture, quorum sensing, biofilms.

• Metabolism (XL3.6): redox energetics, glycolysis, Entner-Doudoroff and pentose phosphate pathways, TCA cycle, fermentation, respiration, chemolithotrophy, photosynthesis.

• Disease and control (XL3.7 and XL3.8): normal microbiota, infection types, pathogenicity, immunity, vaccines, antibiotics and resistance.

• Genetics and ecology (XL3.9 and XL3.10): mutation, bacterial gene transfer, operon model, phage life cycle, microbial genomics, biogeochemical cycles, bioremediation, metagenomics.

XL4 Zoology

• Diversity and evolution (XL4.1 and XL4.2): animal systematics, phylogeny, origin of life, natural selection, speciation.

• Genetics and molecular biology (XL4.3, XL4.4 and XL4.6): inheritance, linkage, population genetics, genetic disorders, nucleic acids, enzymes, hormones, eukaryotic gene regulation, transposable elements.

• Cell biology (XL4.5): microscopy, cytoskeleton, organelles, cell cycle, chromatin.

• Anatomy and physiology (XL4.7): comparative anatomy and the respiratory, muscular, circulatory, digestive, nervous, excretory, endocrine, reproductive and skeletal systems.

• Parasitology and immunology (XL4.8): host-parasite relations, protozoan and helminthic parasites, cellular and humoral immunity.

• Development, ecology and behaviour (XL4.9 to XL4.11): gametogenesis, embryonic development, stem cells, ecosystems, population dynamics, conservation, animal behaviour and communication.

XL5 Food Technology

• Food chemistry and nutrition (XL5.1): carbohydrates, proteins, lipids, pigments, flavours, enzymes, browning, nutrition, anti-nutrients, adulteration.

• Food microbiology (XL5.2): microbial growth and death kinetics (D, Z and F values), spoilage, foodborne pathogens and toxins, fermented foods, probiotics.

• Food products technology (XL5.3): thermal and non-thermal processing, packaging, cereals, oils, fruits and vegetables, plantation crops, milk and animal products, waste utilisation, food standards and quality systems.

• Food engineering (XL5.4): mass and energy balance, momentum, heat and mass transfer, mechanical operations, thermal operations, psychrometric operations.

General Aptitude syllabus

General Aptitude is common to all GATE papers and carries 15 marks in XL. It has four parts:

• Verbal aptitude: grammar, vocabulary in context, reading comprehension and narrative sequencing.

• Quantitative aptitude: data interpretation, ratios, percentages, powers and logarithms, permutations and combinations, series, mensuration, elementary statistics and probability.

• Analytical aptitude: deduction and induction, analogy, numerical relations and reasoning.

• Spatial aptitude: transformation of shapes, paper folding, cutting and patterns in two and three dimensions.

Overlap between subjects

Many topics repeat across sections, so choose your pair with this in mind. Studying a shared topic once and revising it from two angles saves weeks.

How to cover the syllabus

1. Weeks 1 to 8: finish XL0 Chemistry and the core concepts of your two optional subjects, with short notes for each section.

2. Weeks 9 to 12: start General Aptitude practice for 30 minutes a day and add topic-wise questions for each section.

3. Weeks 13 onwards: take full-length timed mocks, analyse each one the same day and revise from your error log.

Topic-wise tests on Testkart and previous year papers help you check each section against the pattern. You can keep your notes handy with GATE Life Sciences study notes and test your pace in GATE Life Sciences mock tests.