Bihar Board 12th Biology Mock Test 2027: Free Online Test, 35 Objective Pattern & Model Paper Practice
Executive Examination Summary
| Examination Feature | Official BSEB Class 12 Specification |
|---|---|
| Exam Name | Bihar School Examination Board (BSEB) Intermediate Annual Examination (I.Sc) |
| Subject | Biology (जीव विज्ञान) — Subject Code: 119 |
| Target Academic Session | 2026–2027 Examination Cycle (February 2027) |
| Total Marks | 100 Marks (70 Marks Theory Written Exam + 30 Marks School Practical) |
| Exam Duration | 3 Hours 15 Minutes (195 Minutes total, includes 15 minutes cool-off reading time) |
| Question Paper Layout | Section A (Objective MCQs) + Section B (Subjective Short and Long Answer Questions) |
| Section A: Objective Questions | 70 Multiple Choice Questions provided; candidates must answer any 35 on the OMR sheet |
| Section A Marks | 35 Marks (1 Mark for each correct answer) |
| Negative Marking | Zero (0) Penalty — No marks deducted for wrong answers |
| Section B: Short Answer Questions | 20 Questions given; candidates answer any 10 (2 Marks each = 20 Marks) |
| Section B: Long Answer Questions | 6 Questions given; candidates answer any 3 (5 Marks each = 15 Marks) |
| Passing Marks (Theory) | Minimum 21 Marks out of 70 (30% passing rule) |
| Passing Marks (Practical) | Minimum 12 Marks out of 30 (40% passing rule) |
| Minimum Aggregate to Pass | Minimum 33 Marks out of 100 overall (Theory and Practical combined) |
| Medium of Exam | Bilingual (Questions printed side-by-side in Hindi and English) |
Biology forms the essential foundation for students taking the Intermediate of Science (I.Sc) in the PCB group. If a student achieves a high score in Biology, this greatly increases their chances of obtaining an overall First Division (that is, 300 or more marks out of 500). Since the subject involves a lot of concepts, those students who know the key terms, the diagrams, and the genetic mechanisms are able to answer the questions much more quickly than students studying calculation-oriented subjects such as Physics or Mathematics.
The Class 12 Biology exam organised by the Bihar Board offers students a significant tactical advantage in that there is a large number of options available. In Section A the board includes 70 objective multiple-choice questions and you are only required to answer 35 of them on your OMR sheet; this enables you to leave out questions you do not know and concentrate instead on the chapters you have studied.
There is a potential problem with having 70 options: it can cause question selection fatigue. A great many students take 40 minutes looking at each question, end up hesitating, and then hurry to fill in their OMR bubbles in the last few minutes. This haste causes errors such as putting answer 18 in row 19 or making foolish mistakes with simple definitions.
By using our BIHAR BOARD CLASS 12TH BIOLOGY MOCK TEST 2027 system and practicing regularly, you will learn how to go through the paper, choose the 35 questions which are the most direct, and then solve them neatly in between 35 and 40 minutes. This will give you enough time to compose well-labelled, structured answers in Section B.
Exam Pattern & Marking Scheme: Theory and Practical
The BSEB Class 12 Biology examination carries 100 total marks, divided between a written theory paper and an internal school practical exam:
| Section / Paper | Total Questions Given | Questions to Attempt | Total Marks | Evaluation & Negative Marking |
|---|---|---|---|---|
| Section-A (OMR MCQs) | 70 questions | of which any 35 must be attempted | carrying 35 marks | at 1 mark each with no negative marking; only the first 35 answers bubbled will be counted. |
| Section-B (Short Answer) | 20 Questions | Any 10 Questions | 20 Marks | 2 marks each (Definitions, Differences, Short Notes) |
| Section-B (Long Answer) | 6 Questions | Any 3 Questions | 15 Marks | 5 marks each (Diagrams, Cycles, Processes) |
| Theory Total | 96 Questions | 48 Questions | 70 Marks | Passing Marks: Minimum 21 Marks (30%) |
| Practical Examination | Lab Experiments, Spotting & Viva | — | 30 Marks | Passing Marks: Minimum 12 Marks (40%) |
| Total Marks | — | — | 100 Marks | Aggregate Passing: Minimum 33 Marks |
Start Bihar Board Class 12th Biology Mock Test 2027 Online
Try an authentic 35-mark multiple-choice test designed to follow the official BSEB pattern, with immediate scoring, detailed step-by-step biological explanations, and comparisons of ranks across the state.
- Free Access Tier: 2 Full-Length 70-Question Tests + All 5 Unit Tests Free
- OMR Simulation Rules: Pick and submit your best 35 questions out of 70
- Languages Supported: Hindi Medium (हिंदी माध्यम) & English Medium
- Features Included: Unit Accuracy Heatmap, Punnett Square Helper, Diagram Labeling Hints
Start Bihar Board Class 12th Biology Mock Test 2027 Online
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Official Updates and Bihar Board Class 12 Examination Status
The annual Intermediate examinations carried out by the Bihar School Examination Board (BSEB), which is headed by Anand Kishore at Sinha Library Road in Patna, take place at various designated centres in Bihar. The verified dates for the 2027 cycle are given below:
| Examination Event | Expected Official Timeline | Current Verification Status | Official Verification Portal |
|---|---|---|---|
| Student registration for Inter Science | September to October 2026 | School Headmaster's files | seniorsecondary.biharboardonline.com |
| Dummy Admit Card Verification | November 2026 | Name, photo, and subject correction | BSEB Senior Secondary Portal |
| Sent-Up (Pre-Board) Practical Exams | Late November 2026 | Conducted at home schools | School Notice Boards |
| Sent-Up (Pre-Board) Theory Exams | Early December 2026 | Mandatory state-wide screening | High School Exam Centers |
| PDF version of the Official Model Papers | Late December 2026 | Download the annual sample papers | biharboardonline.bihar.gov.in |
| Practical Examination Admit Card | Late December 2026 | Required for home school lab tests | School Principal Login |
| Class 12 Practical Examinations | January 10 to January 20, 2027 | External examiner evaluation | Respective School Labs |
| Final Theory Admit Card Release | Third Week of January 2027 | Distributed with official school seal | Designated School Counters |
| Class 12 Biology Theory Exam Date | Early February 2027 (First Week) | Official BSEB Annual Routine | Official BSEB Press Release |
| The BSEB Intermediate annual results for 2027 | late March 2027 (before March 31) | announced on the Online Marksheet Portal | results.biharboardonline.com |
Important notice: The practice materials and test simulations available on this site are created independently by teachers. The site is completely separate from the Bihar School Examination Board (BSEB).
Explained: The 70 versus 35 Objective Rule — Avoid This Important OMR Error
The most frequent mistake made by students in the Bihar Board Class 12 Biology exam is not understanding how the optical scanning machine scores Section A.
Section A contains 70 objective questions, numbered from 1 to 70. You are told to answer any 35 of them. A large number of students wrongly think that if they fill in 45 or 50 bubbles, the scanning system will go through all of them and select the top 35 marks.
This is entirely incorrect.
The computerized OMR scanner goes through your answer sheet one question after another, starting at question 1. As soon as it has detected 35 marked bubbles, it stops right away and does not look at any further questions. Any bubbles marked after the 35th one are ignored.
Consider this example:
- A student marks 45 answers on their OMR sheet.
- Out of the first 35 marked bubbles, they have 24 correct and 11 wrong.
- Questions 36 to 45 are all correct.
- The optical scanner therefore gives a final score of 24 out of 35 and does not assess questions 36 through 45.
That is why it is essential to practice using our bseb class 12 biology 70 objective questions model paper test console. Our platform warns you the moment you try to answer a 36th question, helping you develop the habit of choosing and marking only your best 35 questions.
What Most Free Online Tests Fail to Provide: A Competitive Advantage Analysis
There are many websites in Bihar that offer simple online quizzes for Class 12 Biology, but the majority of these platforms have serious drawbacks. The table below shows what typical websites fail to provide and how our testing platform offers a full testing experience:
| Feature / Preparation Need | What Most Free Websites Offer | How Our Testing Platform Solves It | Direct Benefit to You |
|---|---|---|---|
| OMR Exam Simulation | Short quizzes with only 10 to 15 questions | Full sets of 70 questions, allowing you to select your best 35 answers | Reproduces the real exam room situation of having to decide which questions to answer |
| OMR Evaluation Limit | Allows unlimited submission of questions | Enforces a strict limit of 35 questions and gives instant warnings | Prevents you from losing marks due to the scanner's cutoff rule |
| Genetics Cross Explanations | Gives one-line answers without showing the steps | Provides a full Punnett Square explanation for both monohybrid and dihybrid crosses | Shows you the exact phenotypic and genotypic ratios ($9:3:3:1$, $1:2:1$) |
| Diagram-Based Questions | Offers text-only questions and omits visual biology | Includes high-resolution diagram labeling for flowers, ovules, and human systems | Prepares you for the diagram-based questions that are common in Section A and B |
| Diagnostic Feedback | Only shows a total score at the end | Provides unit-wise accuracy heatmaps for all 5 units | Helps you identify your exact weak chapters so you can decide what to revise next |
| Bilingual Language Toggle | Usually offers only English or poor Hindi translations | Offers verified side-by-side Hindi and English translations | Enables both Hindi and English medium students to practice more clearly |
Complete Unit-Wise Marks Distribution: All 5 NCERT Units
The BSEB Class 12 Biology syllabus is based on 5 main units covering 13 chapters. The table below shows the distribution of questions and the weightage of each unit in recent board examinations:
| Biology Unit | NCERT Chapters Included | Estimated Objective Questions (out of 70) | Estimated Subjective Marks (out of 35) | Total Theory Marks Share (out of 70) | Priority Level |
|---|---|---|---|---|---|
| Unit 2: Genetics & Evolution (आनुवंशिकी तथा विकास) | Chapters 4, 5, and 6 | 18 – 22 Questions | 8 – 10 Marks | ~18 Marks | 🔥 Highest Priority |
| Unit 1: Reproduction (जनन) | Chapters 1, 2, and 3 | 14 – 16 Questions | 6 – 8 Marks | ~14 Marks | High Priority |
| Unit 5: Ecology and Environment (पारिस्थितिकी एवं पर्यावरण) | Chapters 11, 12, and 13 | 14 – 16 Questions | 6 – 8 Marks | ~14 Marks | High Scoring |
| Unit 3: Biology in Human Welfare (मानव कल्याण में जीव विज्ञान) | Chapters 7 and 8 | 12 – 15 Questions | 6 – 8 Marks | ~14 Marks | Direct Memory |
| Unit 4: Biotechnology (जैव प्रौद्योगिकी) | Chapters 9 and 10 | 10 – 12 Questions | 5 – 6 Marks | ~10 Marks | Process Based |
Detailed Micro-Syllabus Breakdown: Unit by Unit
Review this comprehensive micro-syllabus to master every chapter, concept, and named biological experiment:
Unit 1: Reproduction (जनन)
Estimated Theory Weightage: 14 to 16 Objective Questions, ~14 Total Marks
Chapter 1: Sexual Reproduction in Flowering Plants (पुष्पी पादपों में लैंगिक जनन):
Subject matter: the structure of flowers, the development of the male and female gametophytes, microsporogenesis (including the structure of the pollen grain and the vegetative and generative cells), megasporogenesis (involving the structure of the anatropous ovule and the seven-celled, eight-nucleate embryo sac), types of pollination (autogamy, geitonogamy, xenogamy), pollination agents (wind, water, and insects), outbreeding devices, and the interaction between pollen and pistil.
The process of fertilization and what follows it involves double fertilization (that is, syngamy and triple fusion leading to the formation of the triploid primary endosperm nucleus – PEN), the different types of endosperm (either free-nuclear or cellular), the development of the embryo, the structure of dicot and monocot seeds, fruit formation (including true fruits, false fruits and parthenocarpic fruits), and apomixis as well as polyembryony.
Chapter 2: Human Reproduction (मानव जनन):
Micro-Topics: the male reproductive system (structure of the testes, the seminiferous tubules, Sertoli cells, Leydig cells which produce androgens), the female reproductive system (the ovaries, the fallopian tubes, the uterus, the endometrium, the mammary glands), and the microscopic anatomy of the testis and ovary.
The process of gamete formation and fertilization includes spermatogenesis (involving spermatogonia, primary spermatocytes, spermatids, and spermatozoa, with hormonal control provided by LH and FSH), the structure of the sperm cell, oogenesis (which consists of the primary oocyte, the secondary oocyte, and polar bodies), the menstrual cycle (comprising the follicular, ovulatory, and luteal phases; including the LH surge), fertilization taking place in the ampullary region, cleavage, the formation of the morula and blastocyst and subsequent implantation, the development of the placenta and the hormones it produces (hCG, hPL, and relaxin), as well as parturition and lactation.
Chapter 3: Reproductive Health (जनन स्वास्थ्य):
Micro-Topics: the need for reproductive health, the problem of population explosion and the use of birth control, various contraceptive methods (natural or traditional ones, barrier methods, intrauterine devices such as the Copper-T, oral pills such as Saheli, injectables, surgical methods including vasectomy and tubectomy), the rules regarding medical termination of pregnancy (MTP), sexually transmitted diseases (STDs) such as AIDS, gonorrhea, syphilis and genital herpes, infertility and assisted reproductive technologies (ART): in-vitro fertilisation (IVF – the test tube baby), ZIFT, GIFT and ICSI and AI.
Unit 2: Genetics & Evolution (आनुवंशिकी तथा विकास) — Highest Weightage
Estimated Theory Weightage: 18 to 22 Objective Questions, ~18 Total Marks
Chapter 4: Principles of Inheritance and Variation (वंशागति तथा विविधता के सिद्धांत):
Micro-Topics: Mendelian inheritance: Monohybrid cross (Law of Segregation, 3:1 phenotypic ratio, 1:2:1 genotypic ratio), Dihybrid cross (Law of Independent Assortment, 9:3:3:1 ratio), Incomplete Dominance (Antirrhinum/Snapdragon, 1:2:1 phenotypic and genotypic ratio), Co-dominance and Multiple Alleles (ABO blood grouping in humans controlled by IA, IB, i alleles).
The subject of chromosomal genetics and disorders includes the chromosomal theory of inheritance (as proposed by Sutton and Boveri), linkage and recombination (based on Thomas Hunt Morgan's experiments with Drosophila melanogaster), methods of sex determination (in humans, birds, and honeybees: haplodiploidy), mutation (point mutation: sickle-cell anemia; frame-shift mutation), the symbols used in pedigree analysis, Mendelian disorders (such as hemophilia, color blindness, thalassemia, and phenylketonuria), and chromosomal disorders (down syndrome – trisomy 21, Turner syndrome – 45 XO, Klinefelter syndrome – 47 XXY).
Chapter 5: Molecular Basis of Inheritance (वंशागति का आणविक आधार):
Micro-Topics: the structure of DNA and RNA, the composition of the nucleotides, the Central Dogma of molecular biology, and the packaging of the DNA helix (involving a histone octamer and nucleosome structure).
Classic Experiments: Frederick Griffith's Transformation experiment (using Streptococcus pneumoniae), Avery, MacLeod, and McCarty's biochemical characterization, Hershey and Chase experiment (confirming DNA as genetic material using radioactive 35S and 32P in T2 bacteriophage), Meselson and Stahl experiment (semiconservative DNA replication using 15N).
Processes and regulation: enzymes involved in DNA replication (DNA-dependent DNA polymerase), transcription (transcription unit comprising a promoter, a structural gene and a terminator; in eukaryotes RNA polymerases I, II and III; post-transcriptional modifications such as splicing, capping and tailing), the genetic code (universal, degenerate, unambiguous, with the start codon AUG and the stop codons UAA, UAG and UGA), translation (involving the charging of tRNA, initiation, elongation and termination), the Lac operon model of gene regulation (as proposed by Jacob and Monod: the regulator gene i, the promoter p, the operator o, the structural genes z, y and a, and the role of lactose as an inducer), the features of the Human Genome Project (HGP), and the DNA fingerprinting technique (developed by Alec Jeffreys: VNTRs, southern blotting).
Chapter 6: Evolution (विकास):
Micro-Topics: the Oparin-Haldane theory, Stanley Miller and Harold Urey's experiment with electric discharge, evidence for evolution such as paleontological evidence, morphological and anatomical evidence (homologous organs indicating divergent evolution versus analogous organs indicating convergent evolution), and adaptive radiation (for example, Darwin's finches in the Galapagos Islands and the Australian marsupials).
Evolutionary Theories: Lamarckism vs Darwin's theory of Natural Selection, Mutation theory of Hugo de Vries (Saltation), Hardy-Weinberg Principle of genetic equilibrium (p2 + 2pq + q2 = 1; the factors which affect equilibrium are gene flow, genetic drift, mutation, genetic recombination and natural selection; the types of natural selection are stabilizing, directional and disruptive; the stages of human evolution are Dryopithecus, Ramapithecus, Australopithecus, Homo habilis, Homo erectus, Neanderthal man and Homo sapiens).
Unit 3: Biology in Human Welfare (मानव कल्याण में जीव विज्ञान)
Estimated Theory Weightage: 12 to 15 Objective Questions, ~14 Total Marks
Chapter 7: Human Health and Disease (मानव स्वास्थ्य तथा रोग):
Micro-Topics: the concept of health, common infectious diseases in humans—typhoid (caused by Salmonella typhi, diagnosed by the Widal test), pneumonia (caused by Streptococcus pneumoniae), the common cold (caused by rhino viruses), malaria (caused by Plasmodium vivax and falciparum, with a detailed life cycle in both the female Anopheles mosquito and the human host and with the release of hemozoin toxin leading to chills and fever), amoebiasis (caused by Entamoeba histolytica), ascariasis, filariasis/elephantiasis (caused by Wuchereria bancrofti), and ringworm (caused by Microsporum and Trichophyton).
Immunity & Clinical Conditions: Innate immunity (physical, physiological, cellular, and cytokine barriers: interferons), Acquired immunity (Active vs Passive immunity, Humoral vs Cell-Mediated immunity mediated by B-cells and T-cells), Antibodies structure (H2L2, IgG and IgA in colostrum, IgM and IgE in the context of allergies), autoimmunity (such as in the case of rheumatoid arthritis), AIDS (including the structure of HIV, reverse transcriptase, modes of transmission, and the ELISA diagnostic test), cancer (distinguishing between benign and malignant tumors, metastasis, the loss of contact inhibition, oncogenes, biopsy, and chemotherapy), and drug and alcohol abuse (involving opioids/morphine/heroin, cannabinoids, and cocaine/crack).
Chapter 8: Microbes in Human Welfare (मानव कल्याण में सूक्ष्मजीव):
Micro-Topics: In household products, Lactobacillus (LAB) is found in curd, Baker's yeast (Saccharomyces cerevisiae) is used in bread dough, and it is also present in toddy drink; in industrial production, fermented beverages are produced, antibiotics (Fleming's discovery of penicillin from Penicillium notatum), organic acids (citric acid from Aspergillus niger, acetic acid from Acetobacter aceti), enzymes (lipases, the clot-buster streptokinase from Streptococcus), cyclosporin A (an immunosuppressive agent from Trichoderma polysporum), and statins (a blood cholesterol-lowering agent from Monascus purpureus) are manufactured.
Environment and Agriculture: Microbes used in sewage treatment (comparing primary physical treatment with secondary biological treatment which involves an aeration tank and a reduction of biochemical oxygen demand (BOD), as well as an anaerobic sludge digester that produces biogas), the production of biogas in biogas plants (involving Methanobacterium), microbes as biocontrol agents (such as Bacillus thuringiensis / Bt, Trichoderma, and Baculoviruses), and microbes as biofertilisers (including Rhizobium, Azotobacter, Mycorrhiza - Glomus, and Cyanobacteria: Anabaena and Nostoc).
Unit 4: Biotechnology and Its Applications (जैव प्रौद्योगिकी)
Estimated Theory Weightage: 10 to 12 Objective Questions, ~10 Total Marks
Chapter 9: Biotechnology - Principles and Processes (जैव प्रौद्योगिकी - सिद्धांत व प्रक्रम):
Micro-Topics include the principles of genetic engineering, the main tools of Recombinant DNA Technology such as Restriction Enzymes (often referred to as molecular scissors: Endonucleases versus Exonucleases, the recognition of palindromic nucleotide sequences, the action of EcoRI which produces sticky ends), DNA ligase, and Alkaline phosphatase.
Cloning Vectors & Techniques: Features of cloning vectors: Origin of replication (ori), Selectable markers (antibiotic resistance genes ampR and tetR, the β-galactosidase gene can be inactivated by using a chromogenic substrate), there are cloning sites in vectors for plants (using the Agrobacterium tumefaciens Ti plasmid) and for animals (using retroviruses), and methods for transforming competent host cells (such as heat shock, micro-injection, and biolistics/gene gun).
Processes: The isolation of the genetic material (DNA), agarose gel electrophoresis (in which the DNA fragments move towards the anode according to their size and are made visible with ethidium bromide under UV light), the polymerase chain reaction (PCR), involving denaturation at 94°C, annealing at 54°C, and extension at 72°C with the use of heat-stable Taq polymerase obtained from Thermus aquaticus, the use of bioreactors (stirred-tank and sparged bioreactors for large-scale production), and downstream processing (which includes separation and purification).
Chapter 10: Biotechnology and Its Applications (जैव प्रौद्योगिकी एवं उसके उपयोग):
Micro-Topics: Uses in agriculture – Genetically Modified Organisms (GMOs), Bt Cotton (the Cry proteins: cryIAc and cryIIAb which act against bollworms, cryIAb against the corn borer, with the protoxin being activated in the alkaline environment of the insect's gut), RNA Interference (in tobacco plants the use of dsRNA to combat the nematode Meloidogyne incognita).
Medicine and Ethics: in 1983 Eli Lilly produced genetically engineered human insulin (this involved synthesising the A and B chains and joining them with disulfide bonds while at the same time eliminating the C-peptide); gene therapy (the first clinical example of gene therapy took place in 1990 and was for a four-year-old girl who had an Adenosine Deaminase - ADA deficiency); molecular diagnosis (using ELISA and PCR); transgenic animals (the case of Rosie the cow which produced milk enriched with human protein containing alpha-lactalbumin); biopiracy (the illegal exploitation of biological resources and the patenting of Basmati rice by foreign companies); ethical issues and the Genetic Engineering Appraisal Committee (GEAC).
Unit 5: Ecology and Environment (पारिस्थितिकी एवं पर्यावरण)
Estimated Theory Weightage: 14 to 16 Objective Questions, ~14 Total Marks
Chapter 11: Organisms and Populations (जीव और समष्टियाँ):
Micro-Topics: The major abiotic factors include temperature (distinguishing between eurythermal and stenothermal organisms), water, light, and soil; responses to abiotic factors involve regulators, conformers, migration, and suspension (such as diapause in zooplankton, hibernation in bears, and aestivation in snails); adaptations include the example of the kangaroo rat in the North American desert, Allen's Rule (which states that mammals from colder climates have shorter ears and limbs to reduce heat loss), and physiological adaptations to altitude sickness. Population Ecology: Population attributes are natality, mortality, sex ratio, and age pyramids (expanding, stable, and declining); population growth models include exponential growth (dN/dt = rN) and logistic growth (dN/dt = rN((K − N)/K)), with the sigmoid curve and carrying capacity K; population interactions consist of mutualism (such as in lichens and mycorrhiza), competition (as described by Gause's Competitive Exclusion Principle), predation, parasitism (for example, brood parasitism in cuckoos and crows), commensalism (like an orchid on a mango tree), and amensalism (between Penicillium and bacteria).
Chapter 12: Ecosystem (पारितंत्र):
Micro-Topics: The structure and function of an ecosystem, productivity: gross primary productivity (GPP) versus net primary productivity (NPP: NPP = GPP − R), secondary productivity, and the steps in the decomposition process—fragmentation, leaching, catabolism, humification, and mineralization. Energy and pyramids: Energy flow in an ecosystem is unidirectional and follows Lindeman's 10% law of energy transfer; food chains include the grazing food chain (GFC) and the detritus food chain (DFC), along with food webs, trophic levels, ecological pyramids (the pyramid of numbers, the pyramid of biomass—which is upright in terrestrial ecosystems but inverted in aquatic ocean ecosystems, and the pyramid of energy which is always upright and can never be inverted), and ecological succession (primary as opposed to secondary succession, hydrarch as compared to xerarch succession).
Chapter 13: Biodiversity and Its Conservation (जैव विविधता एवं संरक्षण):
Micro-Topics: The levels of biodiversity are genetic diversity (for example, Rauwolfia vomitoria producing reserpine), species diversity, and ecological diversity; global patterns of species diversity show a latitudinal gradient (with biodiversity decreasing from the equator to the poles), and the species-area relationship (as proposed by Alexander von Humboldt: log S = log C + Z log A); the importance of biodiversity is illustrated by David Tilman's long-term ecosystem experiments and Paul Ehrlich's Rivet Popper hypothesis. Losses and conservation: The causes of biodiversity losses are known as "The Evil Quartet"—habitat loss and fragmentation, over-exploitation, invasions by alien species such as Lantana, water hyacinth (Eichhornia), and Nile perch, and co-extinctions; conservation strategies include in-situ conservation (on-site: national parks, wildlife sanctuaries, biosphere reserves, and sacred groves) and ex-situ conservation (off-site: zoological parks, botanical gardens, wildlife safari parks, seed banks, and cryopreservation), the Red Data Book kept by IUCN, endemic species, and the hotspots in India (the Western Ghats, Indo-Burma, and the Himalayas).
Important Scientists Reference List
These scientists and their discoveries are frequently included in BSEB Class 12 Biology exam papers:
- Gregor Johann Mendel: regarded as the father of genetics; he formulated the Laws of Inheritance (the Law of Segregation and the Law of Independent Assortment) through experiments using garden peas (Pisum sativum).
- James Watson and Francis Crick: in 1953 proposed the double helix model of DNA structure, based on X-ray diffraction data obtained by Rosalind Franklin and Maurice Wilkins.
- Thomas Hunt Morgan: considered the father of experimental genetics; he proved the chromosomal theory of linkage and sex-linked inheritance by using fruit flies (Drosophila melanogaster).
- Alec Jeffreys: developed the technique of DNA fingerprinting by using Variable Number Tandem Repeats (VNTRs) as molecular probes.
- Kary Mullis: invented the Polymerase Chain Reaction (PCR) technique in 1983, enabling the rapid amplification of specific DNA fragments.
- Alexander Fleming: discovered the first antibiotic, penicillin, in 1928 from the mould Penicillium notatum while working on Staphylococcus bacteria.
Analysis of the Trend in Previous Year Questions (PYQ)
A review of the recent BSEB Intermediate Biology examination papers shows that the proportions of topics in the objective section remain consistent:
| Question Style Category | Share in 70 Objectives | What It Primarily Evaluates | Recommended Solving Strategy |
|---|---|---|---|
| Direct Recall & Terminologies | 35 Questions | This includes organism scientific names, chromosome numbers, disease vectors, and abbreviations such as IVF, ZIFT, BOD, and ELISA. | Try these first as they can all be answered within 20 minutes without requiring complex deductions. |
| Process and Genetic Ratios | 20 Questions | This covers Mendelian cross ratios, the temperature steps in PCR, and the roles of enzymes such as EcoRI and DNA ligase, as well as the functions of contraceptives. | Attempt these if you need more questions to make up the total of 35. |
| Multi-Statement Conceptual Questions | 15 Questions | These involve multi-step ecological succession sequences, complex states of the lac operon, and detailed evolutionary timelines. | Skip these in Section A since you only need 35 of the 70 answers; therefore, it is best to focus on the direct, single-step questions. |
How many objective type questions are set in the 12th Biology exam of the Bihar Board?
Section-A includes 70 objective multiple choice questions and the students are required to attempt any 35 of them on the OMR sheet; each question answered correctly is awarded one mark, so the objective section amounts to 35 marks.
What is the minimum mark required in Class 12 Biology for BSEB?
In order to pass the BSEB Class 12 Biology exam, a student must obtain at least 21 marks out of 70 in the theory paper (which accounts for 30%) and at least 12 marks out of 30 in the practical section (which accounts for 40%), the total mark being at least 33 out of 100.
Is there going to be negative marking in the Bihar Board 12th Biology exam?
No negative marking is applied; students are given one mark for each correctly filled bubble, with no deduction for incorrect or unanswered questions, and they must attempt all of the 35 objective questions that are allowed without leaving any blank.
What is the weight of the unit in Bihar Board 12th Biology?
The unit on Genetics and Evolution has the greatest weighting at about 18 marks, with Reproduction, Ecology and Environment, and Biology in Human Welfare each carrying 14 marks, and Biotechnology having 10 marks.
What happens if a student tries to answer more than 35 objective questions?
The computer scanner capable of automation looks only at the first 35 answered questions in turn. Questions number 36 to 70 are completely ignored, even if they have been answered correctly.
Built-in Platform Features & AI-Based Weak Area Diagnostics
The real-time diagnostic tools designed for students of the Bihar Board are available on our practice portal at sarkarimocktest.com:
- For each unit, track your accuracy by looking at your performance in the areas of Reproduction, Genetics, Human Welfare, Biotechnology, and Ecology separately and decide if your errors are due to confusing the terminology or to not understanding the processes.
- The system records the number of seconds taken for each question and flags any question which takes more than 55 seconds so that you can work on answering it more quickly.
- Compare your score with those of Intermediate Science candidates from all 38 districts in Bihar, such as Patna, Gaya, Muzaffarpur, Bhagalpur, and Purnea.
- When your accuracy increases, the system will provide you with more questions relating to genetics crosses at the application level and questions based on processes in order to build your confidence for the subjective problems in Section B.
- Explanations of Punnett Squares step by step: All genetics questions come with a complete solution that shows the parental genotypes, the gametes, and the entire Punnett Square matrix together with the phenotypic and genotypic ratios.
- An examination of the strategies used by top scorers who obtained 95 or more marks, focusing on the 35 multiple-choice questions that they chose and the way they paced themselves during the exam.
- Get badges and finish your daily 20-minute practice sessions in order to remain focused while revising.
AI-Based Weak Area Recommendation
Taking practice tests and not looking over the mistakes you've made causes the same errors to be repeated. The system on our platform has an AI-powered diagnostic engine which functions similarly to that of a private tutor.
Here is how the analysis works:
- You take a practice test with 70 questions and mark your answers for 35 of them.
- The engine checks which questions you got right, wrong, or skipped.
- The system will show Genetics Mechanisms in red on your personal dashboard if you get 100% on Ecology and Reproduction but fail to answer the questions about Dihybrid Crosses or the Lac Operon.
- The system gives a suggestion. "You missed 3 questions about finding genotypes in dihybrid test crosses. Look over Chapter 4 crosses. Finish our 10-question Genetics Punnett Square drill before you take your next full test."
Caption: A student dashboard based on AI shows heatmaps by unit, analytics regarding the time spent on each question, and personalized suggestions for revision for BSEB Class 12 Biology.
15 Common Mistakes Aspirants Make in Bihar Board Class 12th Biology
To avoid these common mistakes in your preparation and to safeguard your score:
- Trying to answer more than 35 objectives: Filling in 45 or 50 bubbles on the OMR sheet is a waste of time since the scanner only considers the first 35 bubbles, reading them from top to bottom.
- Confusing incomplete dominance with co-dominance: It is easy to forget that snapdragons show incomplete dominance (resulting in pink flowers and a 1:2:1 ratio), whereas human ABO blood groups exhibit co-dominance (with the I^A and I^B alleles).
- Mixing up the ploidy of the endosperm: You might forget that in angiosperms the endosperm is triploid (3n) because of triple fusion, while in gymnosperms it is haploid (n) and is formed before fertilization.
- Ignoring the theory passing criteria: You may fail to remember that both the theory and practical parts must be passed separately; you must obtain at least 21 marks in the theory section, no matter what your practical score is.
- Confusing Turner’s syndrome with Klinefelter’s syndrome: You could mix up Turner syndrome (45, XO in sterile females) with Klinefelter’s syndrome (47, XXY in sterile males who have gynecomastia).
- Misidentifying the temperatures in the PCR steps: You might confuse the temperatures for denaturation (94°C), annealing (54°C), and extension (72°C using Taq polymerase).
- Drawing inverted energy pyramids: It is a mistake to forget that an ecological pyramid of energy is always upright and can never be inverted under any circumstances.
- Rushing when bubbling on the OMR sheet: You may solve the questions correctly on paper but accidentally fill in the wrong bubble row on the OMR sheet.
- Confusing homologous organs with analogous organs: You might forget that homologous organs have a common origin but different functions (this is divergent evolution), while analogous organs have different origins but similar functions (this is convergent evolution).
- Omitting details about vectors: You might confuse plasmids (such as pBR322) with bacteriophages or forget about the antibiotic resistance genes (amp^R and tet^R) that are used as selectable markers.
- Overlooking the sequence of hormones in the menstrual cycle: You might confuse the roles of FSH, the LH surge, estrogen, and progesterone during the follicular and luteal phases.
- Neglecting to use scientific names: You might misspell or forget the scientific names of pathogenic organisms such as Salmonella typhi, Plasmodium falciparum, and Entamoeba histolytica.
- Studying without a stopwatch: If you do not time yourself while working through practice sets, you will have problems with time management when the real exam comes around.
- Overthinking simple questions: You might spend two minutes discussing subtle exceptions on basic recall questions instead of simply marking the correct answer and moving on.
- Leaving bubbles blank: As there is no negative marking, leaving any of your 35 objective answers unattempted is a missed opportunity.
Preparation Strategy: Theory Objectives, Subjective Steps and Practical Labs
In order to achieve 90 or more marks in Biology, you need to prepare for all three components at the same time:
Preparation Phase
Focus Component
Daily Action Plan
Each day practise solving 35 objective questions within 25 minutes. Pay special attention to direct definitions, scientific names, and chromosome numbers.
Practice drawing and labelling neat biological diagrams (such as the anatropous ovule, human sperm, blastocyst, and the pBR322 vector) and provide bullet-point answers for the 2-mark questions.
Keep a clean practical record notebook. Practice identifying permanent slides under the microscope (such as the stages of mitosis, blastula, and the transverse section of the ovary or testis), and become skilled at carrying out soil and water pH tests.
Complete at least five full-length model papers. Set aside 40 minutes for Section A (OMR), 75 minutes for the short-answer questions, 60 minutes for the long-answer questions, and leave 20 minutes at the end for review.
Recommended Reference Books and Study Materials
Stick to well-established study materials:
| Resource Title | Publisher / Source | How to Use It |
|---|---|---|
| NCERT Biology Class 12 (जीव विज्ञान) | NCERT / BSTBPC Bihar | Your main textbook. Read every line, study the summary boxes, and do all the exercise questions at the end of each chapter. |
| BSEB Official Model Question Papers | Bihar School Examination Board | Practice the latest official model papers to get used to the type of questions and the layout. |
| Target / Alok / Golden BSEB Question Bank | Reputed Bihar Publishers | Go through chapter-wise solved objective and subjective questions from the past 10 years (2015 to 2026). |
| MockTestCenter.com Practice Series | MockTestCenter / Sarkarim | Take timed chapter-wise drills and complete full 70-question OMR simulations with immediate accuracy feedback. |
Eligibility Criteria: Who Can Appear for BSEB Inter Science Biology?
Candidates must meet the standard eligibility requirements set by the Bihar School Examination Board:
| Eligibility Factor | Official Requirement | Key Details |
|---|---|---|
| Academic Stream | Intermediate of Science (I.Sc) | You must be enrolled in Class 12 with Biology as either a compulsory or additional subject. |
| School Affiliation | Recognised Higher Secondary School / College | You must be enrolled in a school or college affiliated with the Bihar School Examination Board. |
| Pre-Board (Sent-Up) Exam | Mandatory Passing Requirement | You must take and pass the school’s Sent-Up theory and practical examinations in November. |
| Minimum Class Attendance | 75% Attendance Requirement | Regular students must meet the board’s minimum attendance policy during the academic year. |
| Registration Record | Valid BSEB Registration Number | You must have an official registration card and roll number issued by the BSEB. |
Bihar Board Class 12th Biology 2027 Important Dates
Stay organised by keeping track of the key dates in the 2027 examination cycle:
| Examination Milestone | Expected Timeline | Official Status |
|---|---|---|
| Examination Form Submission | September to October 2026 | Handled by the school headmaster |
| Dummy Admit Card Verification | November 2026 | Check the spelling of your name and your parent’s name |
| Sent-Up (Pre-Board) Exams | Late November to Early December 2026 | Mandatory internal screening tests |
| Practical Examination Admit Card | Late December 2026 | Required to enter the home school lab exams |
| Inter Biology Practical Exams | January 10 to January 20, 2027 | External evaluation at the home school |
| Final Theory Admit Card Release | Third week of January 2027 | Signed and stamped by the school principal |
| Class 12 Biology Theory Exam Date | Early February 2027 (First week) | State-wide theory exam at designated centres |
| Official Objective Answer Key Release | Late February / Early March 2027 | Available for objection filing on the BSEB portal |
| Inter Science Annual Result Declaration | Late March 2027 (Before March 31) | Online marksheet published on the official portals |
Free vs Paid Mock Test: What You Get
We believe that basic practice should be accessible to all students in Bihar. Here is how the free version compares to the full test package:
| Feature | Component | Free Access Tier | Pro Test Package |
|---|---|---|---|
| Full-Length 70-Question Tests | 2 Full Tests Free | 15 Complete BSEB Simulation Papers | — |
| Chapter-Wise Objective Tests | All 13 Chapters Included | All 13 Chapters with Advanced Question Pools | — |
| Bilingual Language Toggle | Included for All Questions | Included for All Questions | — |
| Genetics Explanations & Crosses | Detailed Text Solutions | Full Step-by-Step Punnett Square Solutions | — |
| Offline Printable PDFs | Sample Model Paper PDF Included | All 15 Full Mocks Available as PDFs with Solutions | — |
| AI Weak Area Heatmap | Basic Overview | Comprehensive Unit-Wise Heatmap & Custom Drills | — |
| All India Rank & State Percentile | Included on Free Tests | Detailed Cohort Analysis & District Rankings | — |
Daily Current Affairs & General Knowledge Quiz
While preparing for your board exams, it is helpful to stay informed about major state and national developments as this builds a strong foundation of general knowledge for future competitive exams such as NEET, CUET, NDA, or nursing and paramedical entrance tests.
How to Apply: Bihar Board Class 12 Inter Science 2027 Exam Form Process
The application process is managed through your school or junior college:
- Get the examination form: Ask your school clerk or headmaster to get the official BSEB Intermediate Science examination form.
- Complete the section on personal details by filling in your name, your father's name, your mother's name, your date of birth, and your Aadhaar number exactly as they are listed on your BSEB Registration Slip.
- Choose your subject combination and make sure that Biology (subject code 119) is selected together with Physics, Chemistry, Hindi, and English.
- You must attach two recent passport-sized colour photographs, a photocopy of your matriculation certificate, and a photocopy of your Class 11 registration slip.
- Pay the examination fee: The fee for the board examination differs slightly according to whether it is for the regular, private or reserved category.
- The headmaster of your school will verify the information and then submit your form online via seniorsecondary.biharboardonline.com.
- Check the Dummy Admit Card: When the board publishes the dummy admit card in November, make sure that your subject codes and personal details are correct. If you spot any errors, inform your school right away so they can make the necessary corrections.
Your Next Step to Score 35/35 in Biology Objectives
Follow this practical daily study plan:
- Go through the micro-syllabus listed above and begin with the Genetics & Evolution chapters that are likely to yield the best results.
- Take fifteen minutes to go over our list of important scientists and the key genetic ratios.
- Get your first free practice test which consists of 70 questions on our platform.
- To develop a good sense of pace and to prevent being penalized for reaching the OMR cutoff, practice by choosing and responding to exactly 35 questions.
- Look over your scorecard, examine your unit accuracy heatmap, and read the step-by-step Punnett square explanations for any questions that you got wrong.