INBO: syllabus, mock tests and practice
Indian National Biology Olympiad — Stage 2 of India's Science Olympiad programme in Biology, conducted by HBCSE. Top scorers qualify for the Orientation-cum-Selection Camp (OCSC), from which 4 students are chosen to represent India at the International Biology Olympiad (IBO). For students in Class X, XI and XII.
- Classes
- Grade 10, Grade 11, Grade 12
- Syllabus years
- 2026-27
- Mock tests
- 7
- Downloads
- 38
About the INBO exam
How the exam works
INBO is the national second-stage Biology Olympiad. Entry comes through NSEB qualification and any officially permitted exemptions. HBCSE administers this stage; qualifying students may proceed to the Orientation-cum-Selection Camp and later team selection. The announced 2027 examination lasts two hours.
Who can apply
The IAPT 2026–27 portal lists Senior Science birth dates 1 July 2007–30 June 2012 and Classes 10–12, subject to the full current eligibility rules. For INO, the official brochure's nationality/residency, school and university conditions and any later amendments also apply. An age/class match alone does not guarantee eligibility.
When it happens
NSEB: 22 November 2026, 14:30–16:30 IST. INBO: 31 January 2027, 13:30–15:30 IST. HBCSE says senior INO selection lists will be published by 15 January 2027, followed by mandatory HBCSE registration. NSE enrolment for this cycle is closed. Checked 1 November 2026.
How to register
For the NSE stage, register through an approved centre or IAPT's self-enrolment portal during the published window; the 2026 fee was ₹300 per subject. Keep personal/parent details, school details and valid identity proof ready. This cycle's entry window is closed. Shortlisted senior candidates must register separately on HBCSE's INO site after the selection list; failure to register can disqualify an otherwise selected student.
Official website, syllabus and past papers
Senior science syllabuses broadly extend through CBSE Class 12, with supporting mathematics. Astronomy emphasises physics, mathematics and elementary astronomy. Include foundational material from earlier classes.
INBO syllabus
INBO syllabus, All classes · 2026-27
Diversity of Living Organisms
- The Living World: Ask what makes something living and study biodiversity, the need for classification and the three domains of life. Learn taxonomy, the taxonomic hierarchy, species concept and binomial nomenclature.
- Biological Classification: Study the five kingdom classification and the main groups of Monera, Protista and Fungi. Learn about lichens, viruses and viroids.
- Plant Kingdom: Learn the features and classification of algae, bryophytes, pteridophytes, gymnosperms and angiosperms.
- Animal Kingdom: Study the features and classification of animals: non-chordates up to phylum level and chordates up to class level.
Structural Organization in Animals and Plants
- Morphology and Anatomy of Flowering Plants: Study the morphology and modifications of root, stem, leaf, inflorescence, flower, fruit and seed. Learn the anatomy and functions of tissues and tissue systems.
- Structural Organisation in Animals: Learn animal tissues and the morphology, anatomy and functions of the digestive, circulatory, respiratory, nervous and reproductive systems.
Cell: Structure and Function
- Cell: The Unit of Life: Study cell theory, prokaryotic and eukaryotic cells, plant and animal cells, the cell envelope and all organelles. Learn cellular respiration: glycolysis, fermentation, TCA cycle, electron transport, ATP yield and respiratory quotient.
- Biomolecules: Study the structure and function of proteins, carbohydrates, lipids and nucleic acids. Learn the types, properties and action of enzymes.
- Cell Cycle and Cell Division: Study the cell cycle, mitosis and meiosis, and why each is important.
Plant Physiology
- Transport in Plants: Study diffusion, osmosis, water potential and plasmolysis, and how water and minerals move long distances. Learn transpiration, stomatal movement, phloem transport and the mass flow hypothesis.
- Mineral Nutrition: Learn essential macro- and micronutrients, deficiency symptoms and toxicity, with hydroponics. Study nitrogen metabolism, the nitrogen cycle and biological nitrogen fixation.
- Photosynthesis and Respiration in Higher Plants: Study photosynthetic pigments, the photochemical and biosynthetic phases, photophosphorylation and the chemiosmotic hypothesis. Learn photorespiration, C3 and C4 pathways and factors affecting photosynthesis.
- Plant Growth and Development: Study seed germination, growth phases and rate, and differentiation. Learn growth regulators, seed dormancy, vernalisation and photoperiodism.
Human Physiology
- Digestion and Absorption: Study the alimentary canal, digestive glands and enzymes, and gastrointestinal hormones. Learn how proteins, carbohydrates and fats are digested and absorbed, calorific values and digestive disorders.
- Breathing and Exchange of Gases: Learn the human respiratory system, the mechanism and regulation of breathing, gas exchange and transport, respiratory volumes and related disorders.
- Body Fluids and Circulation: Study blood composition, blood groups, coagulation and lymph. Learn the structure of the heart, cardiac cycle, ECG, double circulation, regulation of heart activity and circulatory disorders.
- Excretory Products and Their Elimination: Study ammonotelism, ureotelism and uricotelism, and the human excretory system. Learn urine formation, osmoregulation, hormonal control of the kidney, dialysis and kidney disorders.
- Locomotion and Movement: Learn ciliary, flagellar and muscular movement, the contractile proteins and muscle contraction. Study the skeletal system, joints and their disorders.
- Neural Control and Coordination: Study neurons, the central, peripheral and visceral nervous systems, nerve impulse generation and conduction, reflex action and sense organs.
- Chemical Coordination and Integration: Study the endocrine glands and hormones, the mechanism of hormone action, and disorders from hypo- and hyperactivity.
Reproduction
- Reproduction in Organisms: Compare asexual and sexual reproduction, including binary fission, budding, fragmentation and vegetative propagation.
- Sexual Reproduction in Flowering Plants: Study flower structure, gametophyte development, pollination, pollen-pistil interaction and double fertilization. Learn seed and fruit formation, apomixis, parthenocarpy and polyembryony.
- Human Reproduction: Study the male and female reproductive systems, gametogenesis and the menstrual cycle. Learn fertilisation, implantation, pregnancy, placenta, parturition and lactation.
- Reproductive Health: Learn why reproductive health matters, prevention of STDs, birth control and contraception, MTP, amniocentesis, and assisted reproductive technologies such as IVF.
Genetics and Evolution
- Heredity and Variation: Study Mendelian inheritance and its exceptions, multiple alleles, blood groups and polygenic inheritance. Learn the chromosome theory, sex determination, linkage, crossing over, sex-linked traits and Mendelian disorders.
- Molecular Basis of Inheritance: Learn DNA as genetic material, DNA and RNA structure, packaging and replication. Study the central dogma, transcription, the genetic code, translation, the lac operon, the genome and DNA fingerprinting.
- Evolution: Study the origin of life, evidences for evolution and Darwin's contribution. Learn the synthetic theory, mutation, natural selection, gene flow, genetic drift, Hardy-Weinberg principle, adaptive radiation and human evolution.
Biology and Human Welfare
- Human Health and Diseases: Learn common pathogens and parasites, their diseases and control. Study vaccines and basic immunology, cancer, HIV and AIDS, and drug and alcohol abuse.
- Strategies for Enhancement in Food Production: Study plant breeding, tissue culture, single cell protein, biofortification, apiculture and animal husbandry.
- Microbes in Human Welfare: Learn how microbes are used in food processing, industry, sewage treatment, energy generation, bio-control and bio-fertilizers. Study antibiotics and their judicious use.
- Biotechnology: Principles, Processes and Applications: Study recombinant DNA technology and its uses in health and agriculture, such as insulin, vaccines, stem cells and gene therapy. Learn about GM organisms, Bt crops, transgenic animals, biosafety and patents.
Ecology and Environment
- Organisms and Populations: Study habitat and niche, ecological adaptations and population interactions such as mutualism, competition, predation and parasitism. Learn population attributes: growth, birth and death rates and age distribution.
- Ecosystems: Learn ecosystem components, productivity, decomposition and energy flow. Study ecological pyramids, nutrient cycles and ecological succession.
- Biodiversity and its Conservation: Study the concept, patterns and importance of biodiversity, causes of its loss and conservation methods. Learn about hotspots, endangered organisms and extinction.
- Environmental Issues: Learn the causes and control of air and water pollution, agrochemicals, solid and radioactive waste. Study the greenhouse effect, climate change, ozone depletion and deforestation.
Rounds and levels
- 2026-27: Practice for INBO 2026-27 (exam date: 31 January 2027).
- Previous-year papers: Past INBO question papers.
More exams on SkillStar
INBO: questions parents ask
- Which classes can prepare for INBO on SkillStar?
- INBO practice on SkillStar is arranged for Grade 10, Grade 11 and Grade 12. Each child sees what's right for their own class.
- What is in the INBO syllabus for 2026-27?
- 35 topics in Diversity of Living Organisms, Structural Organization in Animals and Plants, Cell: Structure and Function, Plant Physiology, Human Physiology, Reproduction, Genetics and Evolution, Biology and Human Welfare and Ecology and Environment, laid out subject by subject on this page. On SkillStar your child can tick off each topic as they learn it.
- Are there INBO mock tests on SkillStar?
- Yes, 7 mock tests. Each one is marked the moment your child finishes, with a question-by-question review, and can be taken again as often as they like.
- Can I download INBO papers?
- Yes. The INBO Downloads tab on SkillStar has 38 files for this exam.
- How does my child start INBO practice?
- Sign up free as a parent, add your child with their class, and pick INBO from the exam list. Every new family gets welcome credits, lots of content costs nothing, and anything paid shows its price in credits before you decide.
- Is SkillStar the official INBO website?
- No. SkillStar is an independent practice platform and is not affiliated with, or endorsed by, the organisers of these exams. Exam names belong to their respective owners. Check dates, fees and registration with the INBO organisers.
SkillStar is an independent practice platform and is not affiliated with, or endorsed by, the organisers of these exams. Exam names belong to their respective owners.