Class 12 Biology focuses on advanced concepts of life sciences, including reproduction, genetics, evolution, biotechnology, and ecology. It explains how living organisms reproduce, how traits are inherited, how life evolved on Earth, and how biotechnology is used in medicine and agriculture.
Sexual Reproduction in Flowering Plants
Flowers are the seat of sexual reproduction in angiosperms. In the flower, the androecium, consisting of stamens, represents the male reproductive organs and the gynoecium, consisting of pistils, represents the female reproductive organs.
- Structure of Flower
- Microsporogenesis
- Megasporogenesis
- Pollination
- Pollen-Pistil Interaction
- Double Fertilisation
- Post-Fertilization Events
- Seed Formation
- Fruit Formation
- Apomixis and Polyembryony
Human Reproduction
Humans are sexually reproducing and viviparous. This chapter explains the male and female reproductive systems, the process of gamete formation, fertilization, pregnancy and embryo development, and childbirth.
- Male Reproductive System
- Female Reproductive System
- Gametogenesis
- Menstrual Cycle
- Fertilisation and Implantation
- Pregnancy And Embryonic Development
- Parturition and Lactation
Reproductive Health
Reproductive health refers to the total well-being in all aspects of reproduction, i.e., physical, emotional, behavioral, and social. Our nation was the first nation in the world to initiate various action plans at the national level towards attaining a reproductively healthy society.
- Population Stabilisation and Birth Control Methods
- Medical Termination of Pregnancy (MTP)
- Sexually Transmitted Infections (STIs)
- Infertility and Assisted Reproductive Technologies (ART)
Principles of Inheritance and Variation
Genetics is a branch of biology that deals with the principles of inheritance and its practices. Progeny resembling the parents in morphological and physiological features has attracted the attention of many biologists.
- Mendel’s Laws of Inheritance
- Monohybrid Cross
- Dihybrid Cross
- Incomplete Dominance
- Codominance
- Multiple Alleles
- Chromosomal Theory of Inheritance
- Linkage and Recombination
- Polygenic Inheritance
- Pleiotropy
- Sex Determination
- Genetic Disorders
- Mendelian Disorders
- Chromosomal Disorders
Molecular Basis of Inheritance
Nucleic acids are long polymers of nucleotides. While DNA stores genetic information, RNA mostly helps in the transfer and expression of information. Though DNA and RNA both function as genetic material, DNA, being chemically and structurally more stable, is a better genetic material.
- DNA (Deoxyribonucleic Acid)
- Packaging of DNA Helix
- The Search For Genetic Material
- Properties of Genetic Material (DNA versus RNA)
- RNA (Ribonucleic Acid)
- DNA Replication
- The Experimental Proof of DNA Replication
- Transcription
- Genetic Code
- tRNA: The Adapter Molecule
- Translation
- Regulation of Gene Expression
- Lac Operon
- Human Genome Project
- DNA Fingerprinting
Evolution
The origin of life on Earth can be understood only against the background of the origin of the universe, especially Earth. Most scientists believe chemical evolution, i.e., formation of biomolecules, preceded the appearance of the first cellular forms of life. The subsequent events as to what happened to the first form of life are a conjectured story based on Darwinian ideas of organic evolution by natural selection.
- Origin of Life
- Theory of Evolution
- Evidence of Evolution
- Adaptive Radiation
- Biological Evolution
- Hardy-Weinberg Principle
- Brief Account of Evolution
- Origin And Evolution Of Man
Human Health and Disease
Health is not just the absence of disease. It is a state of complete physical, mental, social, and psychological well-being. Diseases like typhoid, cholera, pneumonia, fungal infections of the skin, malaria, and many others are a major cause of distress to human beings.
- Common Diseases
- Bacterial Diseases
- Viral Diseases
- Protozoan Diseases
- Helminth Diseases
- Immunity
- Innate Immunity
- Acquired Immunity
- Antibodies
- Vaccination and Immunisation
- Allergy
- Autoimmune Diseases
- Cancer
- AIDS
- Drug and Alcohol Abuse
Microbes in Human Welfare
Microbes are a very important component of life on Earth. Not all microbes are pathogenic. Many microbes are very useful to human beings. We use microbes and microbially derived products almost every day.
- Microbes in Household Products
- Microbes in Industrial Products
- Microbes in Sewage Treatment
- Biogas Production
- Microbes as Biocontrol Agents
- Biofertilizers
Biotechnology: Principles and Processes
Biotechnology deals with large-scale production and marketing of products and processes using live organisms, cells, or enzymes. Modern biotechnology using genetically modified organisms was made possible only when man learned to alter the chemistry of DNA and construct recombinant DNA. This chapter explains genetic engineering techniques and tools.
- Principles of Biotechnology
- Process of Biotechnology
- Genetic Engineering
- Restriction Enzymes
- Cloning Vectors
- Competent Host (for Transformation With Recombinant DNA)
- Polymerase Chain Reaction (PCR)
- Gel Electrophoresis
- Recombinant DNA Technology
- Bioreactors
Biotechnology and Its Applications
Biotechnology has given humans several useful products by using microbes, plants, animals, and their metabolic machinery. Techniques of tissue culture and somatic hybridization offer vast potential for the manipulation of plants in vitro to produce new varieties.
- Genetically Modified Organisms (GMOs)
- Biotechnological Applications in Agriculture
- Biotechnological Applications in Medicine
- Gene Therapy
- Insulin Production
- Transgenic Animals
- Ethical Issues in Biotechnology
Organisms and Populations
As a branch of biology, Ecology is the study of the relationships of living organisms with the abiotic (physico-chemical factors) and biotic components (other species) of their environment. It is concerned with four levels of biological organization: organisms, populations, communities, and biomes.
- Ecological Adaptations
- Population Attributes
- Population Growth
- Exponential Growth
- Logistic Growth
- Population Interactions
- Predation
- Competition
- Parasitism
- Commensalism
- Mutualism
Ecosystem
An ecosystem is a structural and functional unit of nature, and it comprises abiotic and biotic components. Abiotic components are inorganic materials- air, water, and soil—whereas biotic components are producers, consumers, and decomposers.
- Components of Ecosystem
- Productivity
- Decomposition
- Energy Flow
- Nutrient Cycling
- Food Chain
- Food Web
- Ecological Pyramids
- Ecological Succession
- Carbon Cycle
- Phosphorus Cycle
- Ecosystem Services
Biodiversity and Conservation
Since life originated on Earth nearly 3.8 billion years ago, there has been enormous diversification of life forms on Earth. Biodiversity refers to the total diversity that exists at all levels of biological organization.
- Biodiversity
- Patterns of Biodiversity
- Loss of Biodiversity
- Conservation of Biodiversity
- In Situ Conservation
- Ex Situ Conservation
- Hotspots of Biodiversity