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 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 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
- Structure of Sperm
- 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
Genetics and Evolution
Biology and Human Welfare
Reproductive Health
- Concept of Reproductive Health
- Population Explosion and Birth Control
- 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
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
Ecology
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
Strategies for Enhancement in Food Production
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
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: 10 minutes
CBSE: Class 12
Key Points: Theories and Mechanism of Evolution
- Lamarckism (Lamarck) - Evolution by use/disuse of organs; acquired characters are inherited (e.g., giraffe's neck); eliminated as characters are inherited only through genes.
- Darwinism (Darwin) - Based on Branching Descent (all organisms are modified descendants) and Natural Selection (survival of the fittest).
- Natural selection is based on heritable variations, overproduction, limited resources, struggle for existence, and survival of the fittest, influenced by Thomas Malthus.
- Organisms with heritable variations survive better, reproduce more, and change population characteristics over generations.
- Hugo de Vries' Mutation Theory - Evolution occurs by sudden large mutations (saltation), not gradual changes; experimented on Oenothera lamarckiana.
- Darwin vs Lamarck - Darwin: natural selection + heritable variations (widely accepted); Lamarck: use/disuse + acquired traits (no longer accepted).
- Mendel's inheritable factors and population genetics studies later clarified mechanisms of variation and speciation.
CBSE: Class 12
Evolution in Microbes vs. Longer-Lived Organisms
| Aspect | Microbes | Longer-Lived Organisms |
|---|---|---|
| Reproduction Rate | Fast (within hours) | Slow (years) |
| Population Growth | Millions within hours | Gradual over the years |
| Variation Expression | Quick due to fast division | Slow due to longer life cycles |
| Evolutionary Change Speed | Days | Millions of years |
| Example | Bacterial colony adapting to the medium | Fish or fowl adapting to a new environment |
| Selection for Fitness | Rapid selection based on a new medium | Slow selection based on environmental changes |
| Genetic Basis | Present, inherited quickly | Present, inherited slowly |
| Adaptive Ability | High due to rapid reproduction | Gradual due to a slower lifespan |
| Example | E. coli, Streptococcus spp. | Fish, Fowl |
CBSE: Class 12
Darwin vs. Lamarck
| Concept | Darwin | Lamarck |
|---|---|---|
| Mechanism | Natural selection | Use and disuse of organs |
| Example | Variations in a population lead to the survival of the fittest | Giraffe’s neck elongation due to stretching to reach leaves |
| Heritability | Heritable variations | Acquired traits are passed to offspring |
| Current Acceptance | Widely accepted | No longer accepted |
CBSE: Class 12
Darwin vs. Hugo de Vries
| Aspect | Darwin’s Theory | Hugo de Vries’ Theory |
|---|---|---|
| Source of Variation | Small, heritable variations | Large, sudden mutations |
| Nature of Variation | Directional | Random and directionless |
| Process of Evolution | Gradual | Saltation (sudden changes) |
| Inheritance | Not clearly addressed | Based on mutation |
| Speciation Mechanism | Gradual accumulation of variations | Single-step large mutation |
