| Class 12 Biology Marks Distribution |
| Units | Marks |
| Reproduction | 14 |
| Genetics and Evolution | 18 |
| Biology and Human Welfare | 14 |
| Biotechnology and its Applications | 12 |
| Ecology and Environment | 12 |
| Total | 70 |
CBSE Class 12 Biology Syllabus
- Reproduction in Organisms
- Sexual Reproduction in Flowering Plants
- Human Reproduction
- Reproductive Health
- Principles of Inheritance and Variation
- Molecular Basis of Inheritance
- Evolution
- Human Health and Diseases
- Strategies for Enhancement in Food Production
- Microbes in Human Welfare
- Biotechnology - Principles and Processes
- Biotechnology and its Application
- Organisms and Populations
- Ecosystem
- Biodiversity and its Conservation
- Environmental Issues
Course Syllabus Details
Unit VI. Reproduction
Chapter 1: Reproduction in Organisms
- Reproduction
- A characteristic feature of all organisms for continuation of species
- Modes of Reproduction −
- Asexual reproduction
- Sexual reproduction
- Asexual reproduction −
- Modes-Binary fission
- Sporulation
- Budding
- Gemmule
- Fragmentation
- vegetative propagation in plants
Chapter 2: Sexual Reproduction in Flowering Plants
- Flower structure
- Development of male and female gametophytes
- Pollination −
- Outbreeding devices
- Pollen-Pistil interaction
- Double fertilization
- Post fertilization Events-Development of endosperm and embryo
- Development of seed and formation of fruit
- Special modes −
- Apomixes
- Parthenocarpy
- Polyembryony
- Significance of seed and fruit formation
Chapter 3: Human Reproduction
- Male and female reproductive systems
- Microscopic anatomy of testis and ovary
- Gametogenesis −
- Menstrual cycle
- Fertilisation embryo development up to blastocyst formation, implantation pregnancy and placenta formation (Elementary idea)
- Parturition (Elementary idea)
- Lactation (Elementary idea)
Chapter 4: Reproductive Health
- Need for reproductive health and prevention of sexually transmitted diseases (STD)
- Birth control −
- Need and Methods
- Contraception
- Medical Termination of Pregnancy (MTP)
- Amniocentesis
- Infertility and assisted reproductive technologies −
- IVF
- ZIFT
- GIFT (Elementary idea for general awareness)
Unit VII. Genetics and Evolution
Chapter 5: Principles of Inheritance and Variation
- Mendelian Inheritance
- Deviations from Mendelism −
- Incomplete dominance
- Co-dominance
- Multiple alleles
- Inheritance of blood groups
- Pleiotropy
- Elementary idea of polygenic inheritance
- Chromosome theory of inheritance
- Chromosomes and genes
- Sex determination in −
- Linkage and crossing over
- Sex linked inheritance −
- Haemophilia
- Colour blindness
- Mendelian disorder in humans
- Chromosomal disorders in humans −
- Down's syndrome
- Turner's
- Klinefelter's syndromes
Chapter 6: Molecular Basis of Inheritance
- Search for genetic material and DNA as genetic material
- Structure of DNA and RNA
- DNA packaging
- DNA replication
- Central dogma
- Transcription, genetic code, translation
- Gene expression and regulation −
- Genome and human ganeome project
- DNA fingerprinting
Chapter 7: Evolution
- Origin of life
- Biological evolution and evidences for biological evolution (Paleontological, comparative anatomy, embryology and molecular evidence)
- Darwin's contribution
- Modern Synthetic theory of Evolution
- Mechanism of evolution −
- Variation (Mutation and Recombination)
- Natural Selection with examples
- Types of natural selection
- Gene flow and genetic drift
- Hardy - Weinberg's principle
- Adaptive Radiation
- Human evolution
Unit VIII. Biology and Human Welfare
Chapter 8: Human Health and Diseases
- Pathogens - parasites causing human diseases −
- Malaria
- Filariasis
- Ascariasis
- Typhoid
- Pneumonia
- Common cold
- Amoebiasis
- Ring worm
- Basic concepts of immunology – Vaccines −
- Adolescence, drug and alcohol abuse
Chapter 9: Strategies for Enhancement in Food Production
- Improvement in food production −
- Plant breeding
- Tissue culture
- Single cell protein
- Biofortification
- Apiculature
- Animal husbandry
Chapter-10: Microbes in Human Welfare
- In household food processing
- Industrial production
- Sewage treatment
- Energy generation and as biocontrol agents
- Biofertilizers
- Antibiotics −
- Production and judicious use
Unit IX. Biotechnology and Its Applications
Chapter 11: Biotechnology - Principles and Processes
- Genetic engineering (Recombinant DNA technology).
Chapter 12: Biotechnology and its Application
- Application of Biotechnology in health and agriculture −
- Human insulin and vaccine production, gene therapy
- Genetically modified organisms - Bt crops
- Transgenic Animals; biosafety issues, biopiracy and patents
Unit X. Ecology and Environment
Chapter 13: Organisms and Populations
- Organisms and environment −
- Habitat
- Niche
- Population
- Ecological adaptations
- Population interactions −
- Mutualism
- Competition
- Predation
- Parasitism
- Population attributes −
- Growth
- Birth rate
- Death rate
- Age distribution
Chapter 14: Ecosystem
- Patterns
- Components
- Productivity
- Decomposition
- Energy flow
- Pyramids of number, biomass, energy
- Nutrient cycles (carbon and phosphorous)
- Ecological succession
- Ecological services −
- Carbon fixation
- Pollination
- Seed dispersal
- Oxygen release (in brief)
Chapter-15: Biodiversity and its Conservation
- Concept of biodiversity
- Patterns of biodiversity
- Importance of biodiversity
- Loss of biodiversity
- Biodiversity conservation −
- Hotspots
- Endangered organisms
- Extinction
- Red data book
- Biosphere reserves
- National parks
- Sanctuaries
- Ramsar sites
Chapter-16: Environmental Issues
- Air pollution and its control
- Water pollution and its control
- Agrochemicals and their effects
- Solid waste management
- Radioactive waste management
- Greenhouse effect and climate change
- Ozone layer depletion
- Deforestation
- Any one case study as success story addressing environmental issue(s).
Practical Works
Part A: List of Experiments
- Study pollen germination on a slide.
- Collect and study soil from at least two different sites and study them for texture, moisture content, pH and water holding capacity. Correlate with the kinds of plants found in them.
- Collect water from two different water bodies around you and study them for pH, clarity and presence of any living organisms.
- Study the presence of suspended particulate matter in air at two widely different sites.
- Study of plant population density by quadrat method.
- Study of plant population frequency by quadrat method.
- Prepare a temporary mount of onion root tip to study mitosis.
- Study the effect of different temperatures and three different pH on the activity of salivary amylase on starch.
- Isolation of DNA from available plant material such as spinach, green pea seeds, papaya, etc.
Part B: Study/observation of the following (Spotting)
- Flowers adapted to pollination by different agencies (wind, insect, bird).
- Pollen germination on stigma through a permanent slide.
- Identification of stages of gamete development, i.e., T.S. of testis and T.S. of ovary through permanent slides (from grasshopper/mice).
- Meiosis in onion bud cell or grasshopper testis through permanent slides.
- T.S. of blastula through permanent slides.
- Mendelian inheritance using seeds of different colour/sizes of any plant.
- Prepared pedigree charts of any one of the genetic traits such as rolling of tongue, blood groups, ear lobes, widow's peak and colour blindness.
- Controlled pollination - emasculation, tagging and bagging.
- Common disease causing organisms like Ascaris, Entamoeba, Plasmodium, Roundworm through permanent slides or specimens. Comment on symptoms of disease that they cause.
- Two plants and two animals (models/virtual images) found in xeric conditions. Comment upon their morphological adaptations.
- Two plants and two animals (models/virtual images) found in aquatic conditions. Comment upon their morphological adaptations.
Structure of CBSE Biology Sample Paper for Class 12 Science is
| Type of Question | Marks per Question | Total No. of Questions | Total Marks |
| Very Short Answer Type Questions | 1 | 5 | 5 |
| Short Answer Type Questions - 1 | 2 | 7 | 14 |
| Short Answer Type Questions - 2 | 3 | 12 | 36 |
| Long Answer Type Questions | 3 | 5 | 15 |
| Total | 27 | 70 |
For Preparation of exams students can also check out other resource material
CBSE Class 12 Biology Worksheets
CBSE Class 12 Biology Important Questions
CBSE Class 12 Biology Question Papers
CBSE Class 12 Biology Test Papers
CBSE Class 12 Biology Revision Notes
CBSE Board Examination are often long enough and stressful especially for Class 12th because apart from board exams they are supposed to appear in various other competitive entrance exams depending on which career path they choose.So as students, one does get anxious about the performance in the exams. The key to success in Board exams is preparation right from the start that involves a lot of planning to study, revise and practice. Apart from reference books and notes, Sample papers are very effective study materials for board exam preparation. There are enough reasons that suggest that sample papers hold the key in the successful preparation for final exams. Some of them are mentioned below.
- Since Sample papers are designed as per CBSE guidelines and marking schemes and the whole blueprint is followed thus when a student tries to attempt sample papers they get a complete idea about the type of questions that will be asked in the exam. This gives them an edge to prepare well for the exam.Students get the clear idea how questions are framed, including the type of questions like short or long answer type questions, mostly asked topics, marks distribution, etc.
- CBSE sample papers are a great tool to help in analysis for board exams. As it is based on the latest syllabus updated by the board thereby it covers every question from most of the important topics. Thus solving sample papers help students in analysing their preparation levels for the exam. However the practice should be done in a way that first the paper is solved and then solutions should be consulted to get an analysis of their strong and weak points. This ensures that they are more clear about what to answer and what can be avoided on the day of the exam.
- Solving a lot of sample papers and model test papers gives students a clear idea of what kind of questions are repeatedly being asked and thus they get clarity of which topics are more important and should be emphasised on for revision before attempting the final paper. So attempting papers helps students to prepare well for most frequently asked questions, important questions, and questions that will carry high marks.
- Although students cover up the entire course syllabus by the end of the session, revising again everything becomes a time consuming process which is difficult. Thus with practicing sample papers allows students to check the preparation status of each and every small topic in a chapter. Doing that ensures quick and easy insight into all the important questions and topics in each and every individual. Solving the sample papers also acts as the revision process.
There are many ways to attempt and solve sample and model papers but the best way is to sit in a quiet place at home or somewhere else on a chair with a table similar to examination hall pattern, keeping all stationary required alongside. Make sure you do not have an empty stomach prior to the session. After starting the clock and just like exams, solve the sample paper on an answer sheet just the way it is done in the examination hall. All the distractions which include mobile phone, music, TV or any other stuff should be avoided. If possible one may indulge elder siblings or parents to act as invigilator. Once the sample paper is solved it is advisable to show the answer sheet and the sample paper to your teacher in schools or at tuitions to check.This will make sure you are prepared to give that perfect answer in your final exams.
On ribblu.com you get a lot of resource material to practice which includes sample question papers, worksheets, test papers, previous year board papers, important questions, solved papers, model papers everything free in PDF format.