The NCERT solutions class 12 Biology

NCERT Class 12 Biology: Detailed Overview

Introduction

NCERT Class 12 Biology curriculum is designed to provide students with a comprehensive understanding of biological concepts and principles. The syllabus covers various topics such as reproduction, genetics, evolution, human health, and ecology. The curriculum aims to build a strong foundation for students who wish to pursue higher education and careers in the field of biological sciences.

Chapters and Key Topics

Chapter 1: Reproduction in Organisms

This chapter discusses the biological processes by which new individual organisms are produced. It covers topics such as asexual and sexual reproduction, reproductive health, and the lifecycle of different organisms.

Asexual Reproduction: Binary fission, budding, fragmentation, spore formation, and vegetative propagation.
Sexual Reproduction: Formation of gametes, fertilization, and development of the zygote.
Reproductive Health: Importance of reproductive health, contraceptive methods, and prevention of sexually transmitted diseases.

Chapter 2: Sexual Reproduction in Flowering Plants

This chapter explores the mechanisms of sexual reproduction in angiosperms (flowering plants). It includes the structure of flowers, pollination, fertilization, and the development of seeds and fruits.

Flower Structure: Parts of a flower and their functions.
Pollination: Types of pollination, agents of pollination, and pollination mechanisms.
Fertilization: Double fertilization and the formation of endosperm and embryo.
Seed and Fruit Development: Types of seeds and fruits, and their dispersal mechanisms.

Chapter 3: Human Reproduction

This chapter covers the anatomy and physiology of human reproductive systems. It discusses gametogenesis, the menstrual cycle, fertilization, pregnancy, and childbirth.

Male Reproductive System: Structure and function of male reproductive organs.
Female Reproductive System: Structure and function of female reproductive organs.
Gametogenesis: Spermatogenesis and oogenesis.
Menstrual Cycle: Phases and hormonal regulation.
Fertilization and Pregnancy: Process of fertilization, implantation, and development of the embryo.
Childbirth: Stages of labor and delivery.

Chapter 4: Reproductive Health

This chapter focuses on the significance of reproductive health, birth control methods, and the prevention and management of sexually transmitted infections (STIs).

Reproductive Health: Importance and strategies to maintain reproductive health.
Birth Control Methods: Natural, barrier, hormonal, and surgical methods of contraception.
Sexually Transmitted Infections: Common STIs, their symptoms, and prevention.
Assisted Reproductive Technologies (ART): In vitro fertilization (IVF), surrogacy, and other ART techniques.

Chapter 5: Principles of Inheritance and Variation

This chapter delves into the fundamental principles of genetics, including Mendelian inheritance, genetic disorders, and chromosomal theory of inheritance.

Mendelian Inheritance: Laws of inheritance, monohybrid and dihybrid crosses, and deviations from Mendelian ratios.
Chromosomal Theory of Inheritance: Chromosomes and their role in inheritance.
Genetic Disorders: Types of genetic disorders (autosomal and sex-linked) and their causes.
Variation: Genetic and environmental factors contributing to variation.

Chapter 6: Molecular Basis of Inheritance

This chapter examines the structure and function of genetic material, DNA replication, transcription, translation, and gene regulation.

DNA: Structure of DNA, Watson and Crick model, and properties of the genetic material.
Replication: Process of DNA replication and enzymes involved.
Transcription: Synthesis of RNA from DNA template.
Translation: Protein synthesis from mRNA template.
Gene Regulation: Mechanisms of gene expression and regulation in prokaryotes and eukaryotes.

Chapter 7: Evolution

This chapter explores the mechanisms of evolution, evidences of evolution, and the theories proposed by various scientists.

Theories of Evolution: Lamarckism, Darwinism, and Modern Synthetic Theory.
Mechanisms of Evolution: Natural selection, genetic drift, mutation, and gene flow.
Evidence of Evolution: Fossil records, comparative anatomy, embryology, and molecular evidence.
Human Evolution: Evolutionary history and the development of Homo sapiens.

Chapter 8: Human Health and Disease

This chapter covers the concepts of health and disease, types of diseases, immunity, and strategies for the prevention and control of diseases.

Health and Disease: Definitions and factors affecting health.
Types of Diseases: Infectious and non-infectious diseases, their causes, and symptoms.
Immunity: Types of immunity (innate and acquired), immune system, and vaccines.
Prevention and Control: Measures to prevent and control diseases, including public health strategies.

Chapter 9: Strategies for Enhancement in Food Production

This chapter discusses the various techniques and strategies used to enhance food production, including plant breeding, animal husbandry, and biotechnology.

Plant Breeding: Methods of plant breeding for crop improvement.
Animal Husbandry: Techniques for the management and breeding of livestock.
Biotechnology: Applications of biotechnology in agriculture and food production.
Microbes in Human Welfare: Role of microbes in food production, antibiotics, and biocontrol agents.

Chapter 10: Microbes in Human Welfare

This chapter explores the beneficial roles of microbes in various fields such as food production, medicine, and environmental management.

Microbes in Food Production: Fermentation, probiotics, and biopreservation.
Microbes in Medicine: Antibiotics, vaccines, and gene therapy.
Microbes in Environment: Biodegradation, bioremediation, and biofertilizers.

Chapter 11: Biotechnology: Principles and Processes

This chapter covers the basic principles and techniques of biotechnology, including genetic engineering and its applications.

Genetic Engineering: Recombinant DNA technology, cloning, and gene transfer methods.
Biotechnological Tools: Restriction enzymes, vectors, and polymerase chain reaction (PCR).
Applications: Applications of biotechnology in agriculture, medicine, and industry.

Chapter 12: Biotechnology and its Applications

This chapter discusses the various applications of biotechnology in fields such as agriculture, medicine, and environmental management.

Agriculture: Genetically modified crops, biofertilizers, and biopesticides.
Medicine: Gene therapy, molecular diagnostics, and pharmaceutical products.
Environment: Bioremediation and biofuels.

Chapter 13: Organisms and Populations

This chapter examines the interactions between organisms and their environment, including population dynamics and ecological adaptations.

Population Ecology: Population characteristics, growth models, and regulation.
Interactions: Types of interactions (competition, predation, parasitism, mutualism).
Adaptations: Behavioral, physiological, and structural adaptations of organisms.

Chapter 14: Ecosystem

This chapter covers the structure and function of ecosystems, energy flow, nutrient cycling, and ecosystem services.

Ecosystem Structure: Components of ecosystems (biotic and abiotic).
Energy Flow: Food chains, food webs, and ecological pyramids.
Nutrient Cycling: Biogeochemical cycles (carbon, nitrogen, phosphorus).
Ecosystem Services: Importance and types of ecosystem services.

Chapter 15: Biodiversity and Conservation

This chapter discusses the importance of biodiversity, threats to biodiversity, and strategies for its conservation.

Biodiversity: Levels of biodiversity (genetic, species, and ecosystem diversity).
Threats: Habitat loss, poaching, pollution, and climate change.
Conservation: In situ and ex situ conservation methods, and biodiversity hotspots.

Chapter 16: Environmental Issues

This chapter explores various environmental issues such as pollution, global warming, and sustainable development.

Pollution: Types of pollution (air, water, soil), sources, and effects.
Global Warming: Causes, effects, and mitigation strategies.
Sustainable Development: Principles and practices for sustainable development.
Environmental Protection: Policies, laws, and international efforts for environmental protection.

Biology Chapters

NCERT Class 12 Biology Topics Chapter-wise

I. Reproduction

Reproduction in organisms: Reproduction, a characteristic feature of all organisms for continuation of species; Modes of reproduction – Asexual and sexual; Asexual reproduction; Modes- Binary fission, sporulation, budding, gemmule, fragmentation; vegetative propagation in plants.
Sexual reproduction in flowering plants: Flower structure; Development of male and female gametophytes; Pollination–types, agencies and examples; Outbreedings devices; Pollen-Pistil interaction; Double fertilization; Post fertilization events– Development of endosperm and embryo, Development of seed and formation of fruit; Special modes– apomixis, parthenocarpy, polyembryony; Significance of seed dispersal and fruit formation.
Human Reproduction: Male and female reproductive systems; Microscopic anatomy of testis and ovary; Gametogenesis- spermatogenesis & oogenesis; Menstrual cycle; Fertilisation, embryo development up to blastocyst formation, implantation; Pregnancy and placenta formation (Elementary idea); Parturation (Elementary idea); Lactation (Elementary idea).
Reproductive health: Need for reproductive health and prevention of sexually transmitted diseases (STD); Birth control- Need and Methods, Contraception and Medical Termination of Pregnancy (MTP); Amniocentesis; Infertility and assisted reproductive technologies – IVF, ZIFT, GIFT (Elementary idea for general awareness).

II. Genetics and Evolution

Heredity and variation: Mendelian Inheritance; Deviations from Mendelism– Incomplete dominance, Co-dominance, Complementary genes, Multiple alleles and Inheritance of blood groups, Pleiotropy; Elementary idea of polygenic inheritance; Chromosome theory of inheritance; Chromosomes and genes; Sex determination– In humans, birds, honey bee; Linkage and crossing over; Sex linked inheritance- Haemophilia, Colour blindness; Mendelian disorders in humans– Thalassemia; Chromosomal disorders in humans; Down’s syndrome, Turner’s and Klinefelter’s syndromes.
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– Lac Operon; Genome and human genome project; DNA finger printing.
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) and Natural Selection with examples, types of natural selection; Gene flow and genetic drift; Hardy-Weinberg’s principle; Adaptive Radiation; Human evolution.

III. Biology and Human Welfare

Health and Disease: Pathogens; parasites causing human diseases (Malaria, Filariasis, Ascariasis, Typhoid, Pneumonia, common cold, amoebiasis, ring worm); Basic concepts of immunology–vaccines; Cancer, HIV and AIDs; Adolescence, drug and alcohol abuse.
Improvement in food production: Plant breeding, tissue culture, single cell protein, Biofortification; Apiculture and Animal husbandry.
Microbes in human welfare: In household food processing, industrial production, sewage treatment, energy generation and as biocontrol agents and biofertilizers.

IV. Biotechnology and Its Applications

Principles and process of Biotechnology: Genetic engineering (Recombinant DNA technology).
Application of Biotechnology in health, agriculture and industry: Human insulin and vaccine production, gene therapy; Genetically modified organisms- Bt cotton; Transgenic Animals; Biosafety issues– Biopiracy and patents.

V. Ecology and environment

Organisms and environment: Habitat and niche; Population and ecological adaptations; Population interactions–mutualism, competition, predation, parasitism; Population attributes–growth, birth rate and death rate, age distribution.
Ecosystems: Patterns, components; productivity and decomposition; Energy flow; Pyramids of number, biomass, energy; Nutrient cycling (carbon and phosphorous); Ecological succession; Ecological Services– Carbon fixation, pollination, oxygen release.
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 and sanctuaries.
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 global warming; Ozone depletion; Deforestation; Any three case studies as success stories addressing environmental issues.