Bottle-neck effect is the sudden reduction in population size due to natural calamities or other factors, resulting in random loss of alleles and reduced genetic variation in the surviving population.
Topics
Reproduction in Organisms
- Reproduction
- Modes of Reproduction
- Asexual Reproduction
- Asexual Reproduction in Unicellular Organisms > Binary Fission
- Binary Fission > Simple Binary Fission
- Binary Fission > Transverse Binary Fission
- Binary Fission > Longitudinal Binary Fission
- Asexual Reproduction in Unicellular Organisms > Multiple Fission
- Asexual Reproduction in Unicellular Organisms > Budding
- Asexual Reproduction in Multicellular Organisms > Budding
- Asexual Reproduction in Multicellular Organisms > Gemmule Formation
- Asexual Reproduction in Multicellular Organisms > Regeneration
- Asexual Reproduction in Multicellular Organisms > Fragmentation
- Asexual Reproduction in Multicellular Organisms > Spore Formation
- Binary Vs Multiple Fission
- Vegetative Reproduction or Vegetative Propagation
- Natural Vegetative Propagation
- Artificial Vegetative Propagation
- Sexual Reproduction
- Monocarpic Vs Polycarpic Plants
- Events in Sexual Reproduction
- Pre-fertilization Events
- Fertilization (Syngamy)
- Post-fertilization Events
- Sexual Vs Asexual Reproduction
- Sexuality in Plants
- Sexuality in Animals
- Oviparous Vs Viviparous Animals
- Parthenogenesis (Virgin Birth)
- Oestrus vs Menstrual Cycles
Reproduction
Sexual Reproduction in Flowering Plants
- Sexual Reproduction
- Life Cycle of Angiosperms
- Flower - a Fascinating Organ of Angiosperms
- Types of Flowers
- Structure and Development of Anther
- Microsporogenesis
- Structure and Development of Male Gametophyte
- Structure and Development of Ovule
- Types of Ovules (Based on Orientation)
- Types of Ovules (Based on Integuments)
- Megasporogenesis
- Development of Female Gametophyte or Embryo Sac
- Male Vs Female Gametophytes in Angiosperms
- Pollination
- Self-pollination
- Autogamy
- Cross-pollination
- Geitonogamy
- Outbreeding Devices
- Agents and Types of Cross-pollination
- Anemophily
- Hydrophily
- Entomophily
- Ornithophily
- Cheiropteriphily
- Malacophily
- Wind Vs Insect-pollinated flowers
- Self-pollination Vs Cross-pollination
- Fertilization (Syngamy)
- Artificial Hybridization or Artificial Fertilization
- Pollen Pistil Interaction
- Pollen Germination and Pollen Tube Growth
- Entry of Pollen Tube into Ovule
- Entry of Pollen Tube into the Embryo Sac
- Post-fertilization Events
- Embryo
- Endosperm
- Development of Dicotyledonous Embryo
- Development of Monocotyledonous Embryo
- Parthenocarpy
- Polyembryony
- Apomixis
- Formation of Seed and Fruit
- Significance of Seed Dispersal and Fruit Formation
- The Fruit
- The Seed
- Classification of Seeds
- Dicot Seeds Vs Monocot Seeds
- Structure of Some Common Seeds
- Overview of Sexual Reproduction in Flowering Plants
Genetics and Evolution
Biology and Human Welfare
Human Reproduction
- Human Reproduction
- Secondary Sexual Characteristics in Humans
- Human Reproductive Organs
- The Male Reproductive System
- Testes
- Location and Temperature Regulation of Testes
- Structure of Testis
- Duct system of Male Reproductive Tract
- Accessory Glands of Male Reproductive System
- External Genitalia: Penis
- Semen (Seminal fluid)
- Disorders of Male Reproductive System
- The Female Reproductive System
- External Genitalia: Vulva
- Female Internal Reproductive Organs
- Ovaries
- Ovarian Follicle Development and Function
- Female Reproductive Duct System
- Mammary Glands
- Disorders of Female Reproductive System
- Male Urethra Vs Female Urethra
- Graafian Follicle Vs Corpus Luteum
- Sperm Vs Ovum
- Gametogenesis
- Spermatogenesis
- Phases of Spermatogenesis
- Spermiogenesis
- Factors affecting Spermatogenesis
- Structure of Sperms
- Oogenesis
- Phases of Oogenesis
- Spermatogenesis Vs Oogenesis
- Puberty
- Hormonal Control of Puberty
- Menstrual Cycle (Ovarian Cycle)
- Major Events of Menstrual Cycle
- Hormonal Control of Menstrual Cycle
- Menarche and Menopause
- Embryonic Development in Human
- Fertilization
- Fertilization in Human
- Fate of Germ Layers in Embryonic Development
- Major Features of Embryonic Development
- Placenta (Growth) in Human
- Parturition (Birth) in Human
- Lactation in Human
- Parental Care
Biotechnology and Its Applications
Reproductive Health
- Concept of Reproductive Health
- Population Explosion and Birth Control
- Methods of Birth Control and Contraceptive Devices
- Natural Contraceptive Methods
- Artificial Contraceptive Methods
- Induced Abortion or Medical Termination of Pregnancy (MTP)
- Inequality of Sexes
- Infertility
- Assisted Reproductive Technology (ART)
- In Vitro Fertilization (IVF)
- Amniocentesis
- Genetic Counselling
- Sexually Transmitted Diseases (STD) or Sexually Transmitted Infections (STI)
- Gonorrhoea
- Syphilis
- Genital Herps
- Chlamydiasis
- Genital Warts
- Trichomoniasis
- Hepatitis B
- Acquired Immuno Deficiency Syndrome (AIDS)
Principles of Inheritance and Variation
- Heredity and Variation
- Gregor Johann Mendel – Father of Genetics
- Mendel's Experiments on Inheritance
- Crossing Technique
- Monohybrid Cross
- Dihybrid Cross
- Mendel's Laws > The Law of Dominance
- Mendel's Laws > The Law of Segregation (Law of Purity of Gametes)
- Mendel's Laws > The Law of Independent Assortment
- Basic Terms Used in Inheritance Studies
- Reasons for Mendel's Success
- Applications of Mendel's Laws
- Post Mendelian Genetics
- Exceptions to Mendel's Principles > Incomplete Dominance
- Exceptions to Mendel's Principles > Co-Dominance
- Exceptions to Mendel's Principles > Pleiotropy
- Exceptions to Mendel's Principles > Multiple alleles
- Exceptions to Mendel's Principles > Polygenic traits - Quantitative inheritance
- Pedigree Analysis
- Chromosomal Theory of Inheritance
- Linkage
- Types of Linkage > Complete Linkage
- Types of Linkage > Incomplete Linkage
- Factors Affecting Linkage
- Significance of Linkage
- Linked and Unlinked Genes
- Crossing Over
- Mechanism of Crossing Over
- Types of Crossing Over
- Factors Affecting Crossing Over
- Significance of Crossing Over
- Chromosomal Mapping
- Mapping Technique
- Significance of Chromosome Mapping
- Autosomes and Sex Chromosomes
- Sex Determination
- Basis of Sex Determination
- Sex Determination in Honey Bees
- Sex Linked Inheritance
- Sex Linked Traits
- Morgan and Drosophila
- Sex-linked Inheritance in Drosophila
- Sex-Linked Inheritance in Human Beings
- Colour blindness
- Haemophilia
- Human Genetic Disorders
- Mendelian Disorders in Humans
- Autosomal Abnormalities
- Down's syndrome (Mongolian Idiocy)
- Sex Chromosome Abnormalities
- Disorders of Sex Development due to Sex-Chromosome Abnormality
- Klinefelter's Syndrome
- Turner's Syndrome
- Variation
- Recombinations
- Mutations
- Gene Mutations
- Frame Shift Mutations
- Substitution (Replacement) Mutations
- Chromosomal Mutations or Aberrations
- Deficiency or deletion
- Duplication
- Translocation
- Inversion
- Genomic Mutations or Heteroploidy or Numerical Aberrations
- Aneuploidy
- Euploidy
- Induction of Gene Mutation
- Implications of Mutations
- Polyploidy: Instant Speciation
Ecology and Environment
Molecular Basis of Inheritance
- Concept of Genes
- Nature of Genes
- Direct Evidences for DNA as the Genetic Material
- Properties of Genetic Material
- Indirect Evidences for DNA as the Genetic Material
- DNA Vs RNA
- Tobacco Mosaic Virus (TMV)
- The RNA World
- Biomolecules in the Cell > Nucleic Acids
- Deoxyribonucleic Acid (DNA)
- Purines Vs Pyrimidines
- Chargaff's Rules for Base Pairing in DNA
- Polynucleotide
- Variants of Double Helix DNA
- Prokaryotic DNA Vs Eukaryotic DNA
- Single-stranded DNA (ssDNA)
- Ribonucleic acid (RNA)
- Types of RNA
- Ribosomal RNA (rRNA)
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Prokaryotic mRNA Vs Eukaryotic mRNA
- Various Other Types of RNA
- DNA Replication
- Conservative Replication
- Dispersive Replication
- Semi-Conservative Replication
- Meselson and Stahl’s Experiment
- Enzymes used in DNA Replication
- Mechanism of DNA Replication
- Leading Strand Vs Lagging Strand
- Errors in DNA Replication and Its Repair
- Central Dogma
- Reverse Transcription (Teminism)
- Transcription
- Transcription Unit and the Gene
- Post-transcriptional Processing of RNAs
- Mechanism of mRNA Processing in Eukaryotes
- Translation
- Protein Synthesis in Prokaryotes and Eukaryotes
- Genetic Code
- Characterestic of the Genetic Code
- Chain Initiation and Chain Termination Codons
- Mechanism of Translation
- Mutations and Protein Structure
- Packaging of DNA Helix
- Regulation of Gene Expression
- Induction and Repression
- The Lac Operon
- Human Genome Project
- DNA Fingerprinting
- Rice Genome Project
Origin of Life
- The Universe
- Origin of Solar System
- Origin of Life on Earth
- Theory of Special Creation
- Theory of Spontaneous Generation (Abiogenesis or Autogenesis Theory)
- Theory of Biogenesis
- Biochemical Origin of Life
- First step: Origin of Earth and its Primitive Atmosphere
- Second step: Origin of Molecules and Simple Inorganic Compounds
- Third step: Origin of Organic Compounds
- Fourth step: Origin of Colloids, Coacervates and Individuality
- Fifth step: Origin of Autocatalytic Systems, Genes, Viruses and Primordial Life
- Sixth step: Origin of Primordial Cellular forms of Life (Prokaryotes)
- Seventh step: Origin of Autotrophism
- Eighth step: Origin of Eukaryotic Cells
- Basic Terms related to Origin of Life
- Effects of Oxygen on Evolution
- Development of Life through Evolution
Evidences and Theories of Biological Evolution
- Evidences of Organic Evolution
- Evidence of Evolution > Palaeontological Evidences
- Computation of the Age of a Fossil
- Mass Extinctions
- Geological Time Scale
- Significance of Organic Evolution
- Evolutionary Evidence from Fossil Records
- Evidences from Morphology and Anatomy
- Homology and Homologous Organs
- Analogy and Analogous Organs
- Evidence of Evolution > Vestigial Organs
- Evidence of Evolution > Connecting Links
- Atavism
- Evidence of Evolution > Embryological Evidences
- Temporary Embryonic Structures
- Recapitulation Theory
- Evidences from Cell Biology and Biochemistry
- Molecular (Genetic) Evidences
- Evidences from Geographical Distribution
- Discontinuous Distribution
- Restricted Distribution
- Adaptive Radiation
- Theories and Mechanism of Evolution
- Lamarck’s Theory of Evolution (Lamarckism)
- Basic Postulates of Lamarckism
- Evidences in favor of Lamarckism
- Criticism of Lamarckism
- Neo-Lamarckism
- Darwin’s Theory of Natural Selection (Darwinism)
- Basic Postulates of Darwinism
- Drawbacks and Criticism of Darwinism
- Neo-Darwinism
- Mutation Theory of De Vries
- Modern Theory of Evolution
- Causes of Variations
- Mutations
- Implications of Mutations
- Common Misconceptions about the Theory of Evolution
- Recombinations
- Migration
- Genetic Drift
- Gene Flow
- Selection
- Hardy Weinberg’s Principle
- Bottle Neck Effect
- Types of Selection
- Examples of Natural Selection
- Natural Vs Artificial Selection
- Adaptations
- Process of Adaptation
- Genetic basis of Adaptation
- Convergent and Divergent Evolution
- Speciation
Human Evolution
- Scientific Perspectives on Human Origins
- Place of Man in the Animal Kingdom
- Early Human Ancestors > Prior to Ape Man
- Early Human Ancestors > The Ape Man
- Early Human Ancestors > The Early Man
- Man Vs Ape
- Average Cranial Capacities of Apes and Men
- Stages of Human Evolution
- Social Behaviour in Human Evolution
- The Man of Future
Human Health and Diseases
- Health
- Human Diseases > Communicable Or Infectious Diseases
- Modes of Transmission of Diseases through Pathogens
- Diseases Caused by Bacteria > Typhoid
- Diseases Caused by Bacteria > Pneumonia
- Diseases Caused by Bacteria > Diphtheria
- Diseases Caused by Bacteria > Plague
- Diseases Caused by Viruses > Common Cold
- Diseases Caused by Viruses > Dengue Fever
- Diseases Caused by Viruses > Chikungunya
- Diseases Caused by Protozoa > Malaria
- Diseases Caused by Protozoa > Amoebiasis (Amoeboic dysentery)
- Diseases Caused by Helminths > Ascariasis
- Diseases Caused by Helminths > Filariasis (Elephantiasis)
- Diseases Caused by Fungi > Ringworm
- Human Diseases > Non-communicable or Non-infectious Diseases
- Cancer
- Types of Cancer
- Causes of Cancer
- Organs Commonly Affected by Cancer
- Chemical Carcinogens and their Target Tissues
- Symptoms and Diagnosis of Cancer
- Prevention/Treatment of Cancer
- Pathogens
- Portals of Entry
- Barriers to Invasion by Pathogens
- The Body's Defence Mechanisms
- Protective Surface Phenomenon
- Non-Specific Cellular Responses
- The Immune System
- Lymphoid Organs
- Production of Lymphocytes
- Cellular Immune Response (Response of T-Cells to Antigens)
- Humoral Immune Response (Response of B-Cells to Antigens)
- Antigens
- Antibodies
- Adjunctive Functions of Antibodies
- Mechanism of Action (Effector Mechanisms)
- Allergies
- Immunity
- Types of Immunity > Innate Immunity
- Types of Immunity > Acquired Immunity
- Properties of the Human Immunoglobulins
- Vaccines
- Monoclonal Antibodies
- Interferons
- Autoimmunity
- Immunodeficiency Disorders
- HIV/AIDS
- Organ Transplants and Immunosuppression
- Kidney Transplantation
- Role of Stem Cells in Medical Treatment
- Concept of Adolescence
- Addiction
- Tobacco
- Health Hazards of Tobacco Smoking: Key Facts
- Addiction > Alcohol
- Common Misconceptions about Alcoholism
- Impact of Alcohol Use and Abuse on Health
- Major Risks of Alcoholism
- Symptoms of Alcohol Intoxication
- Cannabis/Cannabinoids
- Drugs
- Types and Effects of Psychoactive Drugs
- Hallucinogens
- Drug Abuse
Strategies for Enhancement in Food Production
- Rise of Agriculture and Settled Life
- Origin of Cultivated Plants
- Green Revolution
- Crop Improvement
- Steps in Plant Breeding
- Methods of Crop Improvement
- Selection
- Types of Selection
- Hybridization
- Hybridization Procedure
- Plant Breeding for Disease Resistance
- Plant Breeding for Developing Resistance to Insect Pests
- Hybrid Vigour (Heterosis)
- Induced Mutations
- Plant Introduction and Acclimatization
- Tissue Culture
- Technique of Tissue Culture
- Components of Culture Media for Cell/Tissue Culture
- Types of Cell/Tissue Culture
- Applications of Tissue Cultures in Crop Improvement
- Single Cell Protein (SCP)
- Biofortification
- Animal Husbandry (Livestock) > Apiculture (Bee Farming)
- Dairy (Livestock) Farm Management
- Cattle Management
- Controlled Breeding Experiments (Artificial Insemination)
- MOET Programme
- Animal Husbandry (Livestock) > Animal Breeding
- Common Livestock Diseases
- Nutritive Value of Milk
- Utility of Cattle
- Livestock Development in India
- Poultry Farm Management
- Poultry Farming Vs Livestock Rearing
- Raising of Poultry
- Nutritive Value of Eggs
- Poultry Development in India
- Honey Bee
- Bee Keeping and Extraction of Honey
- Products of Bee Keeping/ Advantage of Apiculture
- Development of Apiculture in India
- Animal Husbandry (Livestock) > Pisciculture (Fish Farming)
- Fisheries in India
Microbes in Human Welfare
Principles and Processes of Biotechnology
- Principles of Biotechnology
- Genetic Engineering
- Recombinant DNA technology
- Tools of Recombinant DNA Technology
- Restriction Enzymes
- Types of Restriction Enzymes
- Features of an Ideal Vector
- Plasmids
- pBR 322 Vectors
- pUC Vectors
- Agrobacterium tumefaciens
- Phages
- Artificial Chromosomes as Vectors
- Vectors for Cloning Genes in Plants and Animals
- Gene Library
- Cloning
- Processes of Recombinant DNA Technology
- Applications and Risks of Genetic Engineering
- Moral and Ethical Issues of Genetic Engineering
- Genetic Transformation in Plants
- Genetic Transformation in Animals
Biotechnology and Its Applications
- Core Objectives of Biotechnological Research
- Applications of Biotechnology in Agriculture
- Features of Genetically Modified Crops
- Bt Cotton
- Pest-Resistant Plant
- Mechanism of RNA Interference
- Applications of Biotechnology in Health and Medicine
- Genetically Engineered Insulin
- Vaccine Production
- Stem Cell Technology
- Stem Cell Therapy
- Gene Therapy
- Molecular Diagnosis
- ELISA
- Transgenic Animals
- Role of GEAC in Regulating Genetically Modified Organisms in India
- Biopiracy
- Biopatent
- Bioethical Issues
Organisms and Populations
- Ecology and Biomes
- Levels of Ecological Organisation
- Organisms and Their Environment
- Biomes of India
- Major Abiotic Factors
- Climatic Factors > Precipitation
- Climatic Factors > Wind
- Climatic Factors > Temperature
- Climatic Factors > Light
- Climatic Factors > Atmospheric Humidity
- Climatic Factors > Fire
- Topographic Factors
- Atmospheric Factors
- Biotic Factors
- Soil Factors (Edaphic Factors)
- Soil Organisms
- Responses of Organisms to Abiotic Factors
- Habitat
- Niche
- Types of Habitats in the Biosphere
- Adaptations
- Adaptation in Aquatic Plants (Hydrophytes)
- Adaptation in Grassland Plants (Mesophytes)
- Adaptation in Desert Plants (Xerophytes)
- Aquatic Adaptations (Hydrocoles)
- Desert Adaptations (Xerocoles)
- Volant Adaptations
- Cursorial Adaptations
- Fossorial Adaptations
- Arboreal (Scansorial) Adaptations
- Parasitic Adaptations
- Behavioural Adaptations in Animals
- Population Interactions
- Interaction between Organisms
- Intraspecific Relationships
- Dominance Hierarchy (Pecking Order)
- Territoriality
- Altruism
- Animal Societies
- Communication
- Interspecific Relationships
- Positive Interactions > Commensalism
- Positive Interactions > Proto-cooperation
- Positive Interactions > Mutualism (Symbiosis)
- Negative Interactions > Predation
- Negative Interactions > Parasitism
- Negative Interactions > Competition
- Negative Interactions > Amensalism
- Concepts and Measures of Population Ecology
- Environmental Resistance
- Growth Models
- Population Growth
- Carrying Capacity and Its Role in Population Sustainability
- Environmental Stochasticity
- Population Growth Curve
- Population Age Distribution
- Sex Ratio
- Population Dispersal and Energy Flow (Bioenergetics)
- Life History Variation
Ecosystem
- Concept of Ecosystem
- Components of an Ecosystem > Biotic Component
- Producers
- Consumers
- Decomposers
- Key Ecological Terms
- Food Chain
- Types of Food Chains
- Trophic Levels
- Food Web
- Ecological Pyramids
- Components of an Ecosystem > Abiotic Component
- Functions of an Ecosystem
- Structure of Pond Ecosystem
- Flow of Energy
- Productivity
- Efficiencies in Ecosystem
- Decomposition
- Biogeochemical Cycles (Nutrient Cycles)
- The Carbon Cycle
- Phosphorus Cycle
- Biotic or Ecological Succession
- Causes of Succession
- Kinds of Succession
- Major Trends during Succession
- Process of Succession
- Major Trends in Biotic Succession
- Biotic Succession > Hydrosere
- Biotic Succession > Xerosere
- Dominance of Species
- Ecological Services
Biodiversity and Its Conservation
- Biodiversity
- Types of Biodiversity
- Patterns of Biodiversity
- Biodiversity In India
- Measuring Biodiversity
- Importance of Biodiversity
- Rivet-Popper Hypothesis
- Loss of Biodiversity
- Need for Biodiversity Conservation
- Threatened Species
- Endangered Flora and Fauna
- Hotspots of Biodiversity
- Red Data Book
- Genetic Conservation
- Gene Pool
- Genetic Erosion
- Conservation Strategies
- Wildlife Conservation Strategy in India
- Wildlife Acts/Projects of India for Wildlife Conservation
- Protected Areas in India
- Biosphere Reserve
- National Parks
- Wildlife Sanctuary
- Biosphere Reserves Vs National Parks Vs Sanctuary
- Sacred Groves
- Botanical Gardens
- Wildlife Safari
- Seed Bank
- Cryopreservation
- Gene (Germplasm) Banks
- Ramsar Sites
- Conventions on Biological Diversity
- Earth Summit
- World Summit on Sustainable Development (WSSD)
Environmental Issues
- Environmental Pollution
- Kinds of Pollutants
- Air Pollution
- Sources of Air Pollution
- Major Air Pollutants
- Effects of Air Pollution
- Greenhouse Effect
- Global Warming
- El Nino Effect
- Prevention and Control of Air Pollution
- Ozone
- Ozone Layer Depletion
- Acid Rain
- Nuclear Winter
- Climate Change
- Kyoto Protocol
- Water Pollution
- Sources of Water Pollution
- Ganga and Yamuna River Pollution Control Initiatives
- Effects of Water Pollution
- Effect of Agrochemicals
- Environmental Acts
- Prevention and Control of Water Pollution
- Eutrophication
- Biochemical Oxygen Demand (BOD)
- Biological Concentration and Biomagnification
- A Case Study of Integrated Waste Water Treatment
- Ecosan Toilets
- Noise Pollution
- Sources of Noise Pollution
- Effects of Noise Pollution
- Decibel
- Prevention and Control of Noise Pollution
- Radioactive Pollution
- Sources of Radioactive Pollution
- Effect of Radioactive Pollution
- Prevention and Control of Radioactive Pollution
- Soil Pollution
- Sources of Soil Pollution
- Effects of Soil Pollution
- Prevention and Control of Soil Pollution
- Land Degradation
- Soil Erosion
- Prevention and Control of Land Degradation
- Land and Water Management in India
- Wasteland Development
- Solid Waste Management
- E-waste Management
- Deforestation and Its Causes
- Consequences of Deforestation
- Conservation of Forests
- Case Study of People's Participation in Conservation of Forests
- Case Study of Organic Farming
- Case Study of Remedy for Plastic Waste
- Pollution-related Diseases
- Occupational Respiratory Disorders
CISCE: Class 12
