Topics
Reproduction in Organisms
Sexual Reproduction in Flowering Plants
- Flower - a Fascinating Organ of Angiosperms
- Pre-fertilisation in Flowering Plant: Structures and Events
- Structure and Development of Anther
- Microsporogenesis
- Structure and Development of Male Gametophyte
- Pollen Products
- Structure and Development of Ovule
- Megasporogenesis
- Development of Female Gametophyte or Embryo Sac
- Pollination
- Autogamy
- Geitonogamy
- Xenogamy
- Agents of Pollination
- Anemophily
- Hydrophily
- Animal-Mediated Pollination (Zoophily)
- Outbreeding Devices
- Pollen Pistil Interaction
- Artificial Hybridization or Artificial Fertilization
- Double Fertilization and Triple Fusion
- Post-fertilization Events
- Endosperm
- Embryo
- The Seed
- Apomixis
- Polyembryony
Reproduction
Genetics and Evolution
Human Reproduction
- Human Reproduction
- Overview of The Male Reproductive System
- Overview of The Female Reproductive System
- Overview of Gametogenesis
- Structure of Sperms
- 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 Birth Control
- Methods of Birth Control and Contraceptive Devices
- 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
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
Environmental Issues
- 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
- Environmental Issues
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
- Central Dogma
- Reverse Transcription (Teminism)
- Transcription
- Transcription Unit and the Gene
- Process of Transcription in Bacteria
- Process of Transcription in Eukaryotes
- Genetic Code
- Characterestic 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
Ecology
Evolution
- Origin of Life on Earth
- Evolution of Life Forms - a Theory
- Evidences Supporting the Theory of Evolution
- Adaptive Radiation
- Biological 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
- Prevention and Control of Drugs and Alcohol Abuse
- Overview of Human Health and Diseases
Microbes in Human Welfare
Strategies for Enhancement in Food Production
Biotechnology - Principles and Processes
- Biotechnology
- Principles of Biotechnology
- Restriction Enzymes
- Cloning Vectors
- Competent Host (For Transformation with Recombinant DNA)
- Processes of Recombinant DNA Technology
- Overview of Biotechnology - Principles and Processes
Biotechnology and Its Application
- Biotechnology
- Biotechnological Application in Agriculture
- Biotechnological Application in Medicine
- Transgenic Animals
- Ethical Issues
- 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
- Biodiversity
- Species on Earth and Species in India
- Patterns of Biodiversity
- Importance of Species Diversity to the Ecosystem
- Loss of Biodiversity
- Conservation of Biodiversity
- Biodiversity Conservation Methods
- Overview of Biodiversity and Its Conservation
CBSE: Class 12
Key Points: Population Attributes
- A population consists of individuals of the same species living in a defined area, sharing resources and capable of interbreeding.
- Population ecology studies populations because natural selection acts at the population level, linking ecology with evolution.
- Populations have birth rate and death rate (per capita), unlike individuals which have only birth or death events.
- Sex ratio and age structure (represented by age pyramids) are key attributes that indicate whether a population is growing, stable, or declining.
- Population size or density (N) reflects the status of a population and may be measured as number, biomass, or percent cover.
- Population density is often estimated indirectly (e.g., fish caught per trap, tiger census using pug marks) when direct counting is difficult.
CBSE: Class 12
Key Points: Population Interactions
| Interaction Type | Effect on Species A | Effect on Species B | Meaning | Common Examples |
|---|---|---|---|---|
| Predation | + | − | One species (predator) benefits by killing and feeding on the other (prey) | Tiger–deer, starfish–molluscs, herbivores–plants |
| Competition | − | − | Both species compete for the same limited resources, reducing fitness of both | Barnacles, goats–tortoise, plants competing for light |
| Parasitism | + | − | Parasite lives on or inside host and derives nutrition, harming the host | Lice on humans, Plasmodium–human, Cuscuta on plants |
| Commensalism | + | 0 | One species benefits while the other is neither harmed nor benefited | Orchid on mango tree, egret–cattle, clown fish–anemone |
| Mutualism | + | + | Both species benefit from the interaction | Lichen, mycorrhiza, fig–wasp, plant–pollinator |
| Amensalism | − | 0 | One species is harmed while the other remains unaffected | Antibiotic secretion killing nearby microbes |
