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
- Explanation
- Laws: Law of Dominance
Explanation
Law of Dominance states that “When two homozygous individuals with one or more sets of contrasting characters are crossed, the characters that appear in the F1 hybrid are dominant and those that do not appear in F1 are recessive characters".
According to the law of dominance:
- The law of dominance is used to explain the expression of only one of the parental characters in a monohybrid cross in the F1 and the expression of both in the F2 generation. It also explains the proportion of 3:1 obtained at the F2.
- The characters are controlled by discrete units called factors, which are now called alleles.
- Factors occur in pairs.
- In a dissimilar pair of factors, one member of the pair is dominant and the other is recessive.
For example - Tallness in pea plants is a dominant character, while dwarfness is a recessive character.
- In a cross between pure tall and pure dwarf pea plant, the only tall character is expressed in all the individuals of F1 generation. As a result, tallness is the dominant character in pea plants, while dwarfness is a recessive character.
- Tallness in F1 hybrid is determined by genotype Tt, in which the dominant allele 'T' suppresses the recessive allele 't', thereby suppressing its expression in the phenotype.
- The Law of dominance is significant and true but it is not universally applicable.
CBSE: Class 12
CISCE: Class 10, 12
CISCE: Class 10, 12
Laws: Law of Dominance
The law of dominance states that, out of a pair of allelomorphic characters one is dominant and the other recessive.
- In a pair of contrasting traits, only one trait is expressed—this is the dominant trait.
- The trait that remains unexpressed is called recessive.
- The recessive trait can express itself only when both alleles are recessive (homozygous recessive).
