Topics
Reproduction
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
- Dicotyledonous Embryo
- Monocotyledonous Embryo
- The Seed
- Apomixis
- Polyembryony
Reproduction in Organisms
Genetics and Evolution
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
- Fertilization in Human
- Implantation in Human
- Pregnancy and Embryonic Development
- Parturition (Birth) in Human
- Lactation in Human
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
Biology and Human Welfare
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
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
Biotechnology
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
- Transfer RNA (tRNA)
- 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
- Types of Selection
- Brief Account of Evolution
- Human 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
- 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
Strategies for Enhancement in Food Production
Microbes in Human Welfare
Biotechnology - Principles and Processes
Biotechnology and Its Application
Organisms and Populations
- Organisms and Their Environment
- Population and 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)
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 the 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, IMR, and increased life expectancy.
- Population explosion leads to a scarcity of basic needs such as 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.
