Topics
Sexual Reproduction in Flowering Plants
- Flower
- Pre-fertilisation in Flowering Plant: Structures and Events
- Structure and Development of Anther
- Microsporogenesis
- Structure and Development of Male Gametophyte
- Pollen Viability and Storage
- Structure and Development of Ovule
- Megasporogenesis
- Development of Female Gametophyte or Embryo Sac
- Pollination
- Autogamy
- Geitonogamy
- Cross-pollination
- Agents of Pollination
- Anemophily
- Hydrophily
- Animal-Mediated Pollination (Zoophily)
- Outbreeding Devices
- Pollen Pistil Interaction
- Artificial Hybridization or Artificial Fertilization
- Double Fertilization and Triple Fusion
- Events in Sexual Reproduction > Post-Fertilization Structures and Events
- Endosperm
- Embryo
- The Seed
- Apomixis
- Polyembryony
Reproduction
Reproduction in Organisms
Human Reproduction
- Human Reproduction
- The Male Reproductive System
- The Female Reproductive System
- Gametogenesis
- Spermatogenesis
- Structure of Sperm
- Spermiogenesis
- Oogenesis
- Menstrual Cycle (Ovarian Cycle)
- Major Events of Menstrual Cycle
- Menstrual Hygiene
- Fertilisation in Human
- Implantation in Human
- Pregnancy and Embryonic Development
- Parturition (Birth) in Human
- Lactation in Human
Genetics and Evolution
Biology and Human Welfare
Reproductive Health
- Concept of Reproductive Health
- Population Explosion and Control Measures
- Birth Control
- Natural Contraceptive Methods
- Artificial Contraceptive Methods
- Induced Abortion or Medical Termination of Pregnancy (MTP)
- Sexually Transmitted Diseases (STD) or Sexually Transmitted Infections (STI)
- Infertility
- Assisted Reproductive Technology (ART)
- Amniocentesis
- Genetic Counselling
Environmental Issues
- Controlling Vehicular Air Pollution: a Case Study of Delhi
- Effects of Domestic Sewage and Industrial Effluents on Water
- Solid Wastes
- Radioactive Wastes
- Greenhouse Effect and Climate Change
- Ozone Depletion in the Stratosphere
- Degradation by Improper Resource Utilisation and Maintenance
- Radioactive Waste Management and E-waste
Biotechnology
Principles of Inheritance and Variation
- Heredity and Variation
- Gregor Johann Mendel – Father of Genetics
- Mendel's Experiments on Inheritance
- Monohybrid Cross
- Punnett Square
- Back Cross and Test Cross
- Mendel's Laws > The Law of Dominance
- Mendel's Laws > The Law of Segregation (Law of Purity of Gametes)
- Exceptions to Mendel's Principles > Incomplete Dominance
- Exceptions to Mendel's Principles > Co-Dominance
- Dihybrid Cross
- Mendel's Laws > The Law of Independent Assortment
- Chromosomal Theory of Inheritance
- Linkage and Recombination
- Polygenic Inheritance
- Exceptions to Mendel's Principles > Pleiotropy
- Sex Determination
- Sex Determination in Humans
- Sex Determination in Honey Bees
- Mutations
- Pedigree Analysis
- Mendelian Disorders in Humans
- Chromosomal Disorders or Abnormalities
Ecology
Molecular Basis of Inheritance
- Deoxyribonucleic Acid (DNA)
- Structure of Polynucleotide Chain
- Packaging of DNA Helix
- Search for Genetic Material
- Griffith’s Experiment
- Avery, McCarty and MacLeod’s Experiment
- The Hershey-Chase Experiment
- Properties of Genetic Material
- The RNA World
- DNA Replication
- Conservative Replication
- Dispersive Replication
- Semi-Conservative Replication
- Meselson and Stahl’s Experiment
- Enzymes used in DNA Replication
- Mechanism of DNA Replication
- Protein Synthesis
- Reverse Transcription (Teminism)
- Transcription
- Transcription Unit and the Gene
- Process of Transcription in Bacteria
- Process of Transcription in Eukaryotes
- Genetic Code
- Characteristics of the Genetic Code
- Mutations and Genetic Code
- tRNA – the Adapter Molecule
- Translation
- Regulation of Gene Expression
- The Lac Operon
- Human Genome Project
- DNA Fingerprinting
Evolution
- Origin of Life on Earth
- Urey and Miller’s Experiment
- Evolution of Life Forms - a Theory
- Evidences Supporting the Theory of Evolution
- Adaptive Radiation
- Theories and Mechanism of Evolution
- Theories and Mechanism of Evolution
- Hardy Weinberg’s Principle
- Brief Account of Evolution
- Human Evolution
- Overview of Evolution
Human Health and Diseases
- Concept and Determinants of Health
- Modes of Transmission of Diseases through Pathogens
- Diseases Caused by Bacteria > Typhoid
- Diseases Caused by Bacteria > Pneumonia
- Diseases Caused by Viruses > Common Cold
- 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
- Prevention and Control of Infectious Diseases
- Immunity
- Types of Immunity > Innate Immunity
- Types of Immunity > Acquired Immunity
- Active and Passive Immunity
- Vaccination and Immunization
- Allergies
- Autoimmunity
- The Immune System
- Acquired Immuno Deficiency Syndrome (AIDS)
- Cancer
- Causes of Cancer
- Symptoms and Diagnosis of Cancer
- Prevention/Treatment of Cancer
- Drugs and Alcohol Abuse
- Addiction and Dependence
- Effects of Drug and Alcohol Abuse
- Prevention and Control of Drugs and Alcohol Abuse
- Overview of Human Health and Diseases
Microbes in Human Welfare
- Microorganisms (Microbes) and Microbiology
- Microbes in Household Products
- Microbes in Industrial Products
- Microbes in Sewage Treatment
- Microbes in Production of Biogas
- Microbes as Biocontrol Agents
- Microbes as Biofertilizers
- Applications of Biotechnology in Health and Medicine
- Overview of Microbes in Human Welfare
Strategies for Enhancement in Food Production
Biotechnology - Principles and Processes
Biotechnology and Its Application
- Concept of Biotechnology
- Biotechnological Application in Agriculture
- Biotechnological Application in Medicine
- Transgenic Animals
- Bioethics
- Overview of Biotechnology and Its Application
Organisms and Populations
- Organisms and Their Environment
- Ecology
- Population Attributes
- Population Growth
- Life History Variation
- Population Interactions
- Negative Interactions > Predation
- Negative Interactions > Competition
- Negative Interactions > Parasitism
- Positive Interactions > Commensalism
- Positive Interactions > Mutualism (Symbiosis)
- Overview of Organisms and Populations
Ecosystem
Biodiversity and Its Conservation
Estimated time: 13 minutes
CBSE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Introduction
Population Explosion refers to the rapid, unsustainable increase in the size of a human population, driven by a sharp decline in death rates while birth rates remain high, leading to a severe imbalance between population growth and available resources.
- The 20th century saw unprecedented improvements in healthcare, sanitation, and nutrition. While these advances greatly improved quality of life, they also led to an explosive rise in the global population.
- The world population, which was around 2 billion in 1900, rocketed to about 6 billion by 2000 and 7.2 billion in 2011.
- India followed a similar trend. The population at the time of Independence (1947) was approximately 350 million, which crossed the billion mark by 2000 and reached 1.2 billion in May 2011.
- According to the 2011 Census, India's population growth rate was less than 2% (20/1000/year) - a rate that, though seemingly small, leads to millions of additional people every year.
CBSE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Causes of Population Explosion
- A rapid decline in the death rate due to better medical care
- Decline in Maternal Mortality Rate (MMR)
- Decline in Infant Mortality Rate (IMR)
- An increased number of people in the reproductive age group
- Elimination of natural checks, such as famines and epidemics, through modern science
- Improvements in living conditions and sanitation
CBSE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Effects of Population Explosion
Unchecked population growth places immense pressure on a nation's resources and infrastructure. Despite significant progress in agriculture and industry, rapid population growth can negate developmental gains.
- Absolute scarcity of basic necessities - food, shelter, and clothing
- Increased unemployment and poverty
- Strain on healthcare and education systems
- Environmental degradation - deforestation, pollution, resource depletion
- Bottleneck in national economic progress
- Risk of starvation and malnutrition in vulnerable populations
CBSE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Government Measures to Control Population
India was among the first countries in the world to initiate a national family planning programme in 1951. Since then, a range of social, legislative, and medical measures have been implemented.
- "Hum Do Hamare Do" campaign - promoting the ideal of a family with two children through mass media, posters, and advertisements.
- One Child Norm - voluntarily adopted by many urban, working-class couples.
- Statutory Marriageable Age - minimum age of marriage raised to 18 years for females and 21 years for males to reduce early pregnancies.
- Incentives for couples with small families to encourage family planning.
- Use of Contraceptives - the most important and widely promoted measure.
- Mass media campaigns - TV, radio, and print media are used to spread awareness about family planning and contraception.
CBSE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12
Key Points: Population Stabilisation and Control Measures
- Rapid population growth is due to improved health facilities, reduced death rate, MMR and IMR, and increased life expectancy.
- Population explosion leads to scarcity of basic needs like food, shelter and clothing and affects national development.
- Birth control is essential to maintain a balance between the birth and death rates and to ensure the sustainable use of resources.
- Government measures include family planning programmes (RCH), promotion of the small-family norm, raising the marriageable age, and incentives for small families.
- Contraceptive methods and awareness through mass media help prevent unwanted pregnancies and control population growth.
