NCERT Solutions
Class 12 Biology
15 chapters · 29 important questions
Reproduction in Organisms
Covers asexual and sexual reproduction, life span of organisms, and phases of life cycle. Key concepts: clones, vegetative propagation, and gametogenesis.
Key Topics
Important Questions
Why is sexual reproduction evolutionarily advantageous over asexual reproduction?
Sexual Reproduction in Flowering Plants
Covers flower structure, microsporogenesis, megasporogenesis, pollination, fertilisation, and seed/fruit development. Double fertilisation is a critical concept.
Key Topics
Important Questions
Describe double fertilisation in angiosperms. What is its significance?
Draw a well-labelled diagram of a mature embryo sac of an angiosperm.
Human Reproduction
Covers male and female reproductive systems, gametogenesis, menstrual cycle, fertilisation, and embryo development. Spermatogenesis vs oogenesis comparison is important.
Key Topics
Important Questions
Draw a diagram of the male reproductive system and label any five parts.
Describe the menstrual cycle. What are the roles of FSH and LH?
Reproductive Health
Covers STIs, contraceptive methods, assisted reproductive technologies (ART), and amniocentesis. MTP and population explosion are social aspects included.
Key Topics
Important Questions
What is IVF? Describe the steps involved.
What is amniocentesis? Why is it banned in India for sex determination?
Principles of Inheritance and Variation
Covers Mendel's laws, deviations from Mendelism (codominance, incomplete dominance), chromosomal theory, linkage, crossing over, sex-linked inheritance, and chromosomal disorders.
Key Topics
Important Questions
Explain the inheritance of ABO blood groups in humans. Why is it an example of codominance and multiple allelism?
What is crossing over? What is its significance?
Molecular Basis of Inheritance
Covers DNA structure, replication, transcription, translation (protein synthesis), and gene regulation. lac operon is a key gene regulation model. Human Genome Project is included.
Key Topics
Important Questions
Explain the lac operon model of gene regulation in E. coli. Distinguish between inducible and repressible operons.
Describe the semi-conservative mode of DNA replication. Who proved it experimentally?
Evolution
Covers the origin of life, theories of evolution (Lamarckism, Darwinism, Neo-Darwinism), Hardy-Weinberg principle, and speciation. Industrial melanism is a classic example.
Key Topics
Important Questions
Explain Hardy-Weinberg principle. What are the forces that disturb this equilibrium?
What is industrial melanism? How does it support Darwin's theory?
Human Health and Disease
Covers infectious diseases (bacterial, viral, fungal, protozoan), immunity (innate and acquired), vaccines, cancer, drugs and alcohol. AIDS and its causative agent are frequently asked.
Key Topics
Important Questions
What is the difference between innate and acquired immunity? Explain with examples.
How does HIV cause AIDS? Describe the stages of HIV infection.
Strategies for Enhancement in Food Production
Covers plant breeding (hybridisation, mutation), animal husbandry, tissue culture, and single cell protein. Green Revolution and its significance are important.
Key Topics
Important Questions
What is tissue culture? What are its advantages in plant breeding?
What is biofortification? Give two examples of biofortified crops.
Microbes in Human Welfare
Covers microbes in food processing, industrial production, sewage treatment, biogas production, and biocontrol agents. Antibiotics and their production are included.
Key Topics
Important Questions
Explain the process of sewage treatment. Distinguish between primary and secondary treatment.
What are biofertilizers? Give two examples and their uses.
Biotechnology: Principles and Processes
Covers recombinant DNA technology, restriction enzymes, vectors, PCR, and gel electrophoresis. The tools and techniques of genetic engineering are the core of this chapter.
Key Topics
Important Questions
What are restriction enzymes? How do they work? Give one example.
Describe the steps involved in recombinant DNA technology.
Biotechnology and its Applications
Covers GMOs (Bt crops, Golden Rice), genetically engineered insulin, gene therapy, ELISA, and ethical concerns. Bt cotton and Golden Rice are key examples.
Key Topics
Important Questions
How was human insulin produced using genetic engineering? Why was this important?
What is gene therapy? Explain with the example of ADA deficiency.
Organisms and Populations
Covers ecology, biotic/abiotic factors, population attributes, and interspecific interactions. Predation, competition, mutualism, commensalism, parasitism, and amensalism are important.
Key Topics
Important Questions
Distinguish between exponential and logistic population growth. Draw and explain the graphs.
What is the difference between predation and parasitism? Give one example of each.
Ecosystem
Covers structure and function of ecosystems, food chains and food webs, productivity, decomposition, and energy flow. Ecological pyramids and nutrient cycling (carbon, phosphorus) are included.
Key Topics
Important Questions
Explain the 10% law of energy transfer. Why is the pyramid of energy always upright?
What is decomposition? What are the steps involved?
Biodiversity and Conservation
Covers types of biodiversity, species diversity patterns, threats to biodiversity, and conservation methods (in situ and ex situ). Red Data Book and hotspots are included.
Key Topics
Important Questions
What is biodiversity? Explain the types of biodiversity loss. What are the major causes?
Distinguish between in situ and ex situ conservation with examples.