Biology Theory Notes

Cell structure and organization

Cell Theory and Basic Cell Structure: The fundamental principles stating that all living organisms are composed of cells, cells are the…

Chemical and Physical Basis of Life

Water is a polar molecule, essential for life, acting as a universal solvent due to its unique hydrogen bonding capabilities and crucial…

Mendel's experiments

Mendelian Genetics and Inheritance Patterns: Mendelian genetics refers to the principles of inheritance discovered by Gregor Mendel through…

Non-Mendelian genetics

Non-Mendelian Inheritance Patterns: Patterns of inheritance that do not follow Mendel's laws of segregation and independent assortment,…

Evolution and gene frequencies

The Hardy-Weinberg equilibrium is a principle stating that the genetic variation in a population will remain constant from one generation…

Structure and function of genetic materials

DNA Structure and Properties: Deoxyribonucleic acid (DNA) is a double-stranded helical molecule composed of nucleotides, each containing a…

Genes and gene expression

Genome Organization: The complete set of genetic material present in an organism, including both coding and non-coding DNA sequences,…

Molecular basis of mutations

Mutation Definition and Types: A mutation is a permanent alteration in the DNA sequence that makes up a gene, ranging from a single base…

Gene technology tools and methods

DNA Isolation and Analysis Techniques: DNA isolation is the process of extracting DNA from cells or tissues, which is the fundamental first…

Applications of gene technology

Genetically Modified Organisms (GMOs): Organisms whose genetic material has been altered using genetic engineering techniques, resulting in…

Diversity of organisms

Biological Classification Systems: The systematic arrangement of organisms into hierarchical groups based on shared characteristics and…

Diversity of microorganisms

Nature and Types of Microorganisms: Microorganisms are microscopic living organisms that are too small to be seen with the naked eye,…

Basic microbiology techniques

Sterilization Techniques: Sterilization refers to the complete elimination or destruction of all forms of microbial life including…

Resource acquisition and transport in plants

Plant Resource Acquisition: The process by which vascular plants obtain essential resources including water, minerals, and gases from their…

Plant reproduction

Plant Reproduction Systems: Plant reproduction refers to the biological process by which plants produce new individuals, either sexually…

Plant responses to signals

Plant Hormones (Phytohormones): Chemical messengers produced in specific plant tissues that regulate growth, development, and responses to…

Nervous coordination overview

Need for Coordination in Animals: Coordination refers to the integration and regulation of various physiological processes and activities…

Human nervous system structure

Organization of the Human Nervous System: The human nervous system is organized into two main divisions: the Central Nervous System (CNS)…

Nerve impulse generation and transmission

Resting Potential and Action Potential: Resting potential is the electrical potential difference across the plasma membrane of a neuron…

Nervous system disorders

Nervous System Disorders: Abnormal conditions affecting the structure or function of the nervous system that impair normal neurological…

Sensory structures

Sensory Receptors: Specialized cells or nerve endings that detect specific types of stimuli from the internal or external environment and…

Eye and ear structure and function

Structure-Function Relationship in Sensory Organs: The principle that the physical arrangement and components of sensory organs are…

Immunity

Types of Immunity: Immunity refers to the body's ability to resist and fight against infections and diseases caused by pathogens like…

Endocrine system

Endocrine Glands and Hormones: Endocrine glands are ductless glands that secrete hormones directly into the bloodstream, while hormones are…

Homeostasis

Homeostasis is the maintenance of a relatively constant internal environment within a narrow range despite changes in the external…

Types of reproduction in animals

Asexual Reproduction: A type of reproduction that involves a single parent and produces offspring that are genetically identical to the…

Male reproductive system

Gross Anatomy of Male Reproductive System: The male reproductive system consists of primary reproductive organs (testes) and accessory…

Female reproductive system

Female Reproductive System Anatomy: The female reproductive system consists of internal and external organs that work together to produce…

Fertilization to birth

Fertilization and Early Development: Fertilization is the process where a sperm cell fuses with an egg cell (ovum) to form a zygote,…

Reproductive health

Reproductive Health Awareness: Reproductive health refers to the complete physical, mental, and social well-being in all matters relating…

Skeletal systems and movement

Types of Animal Skeletons: The three main types of skeletal systems found in animals: hydrostatic skeleton, exoskeleton, and endoskeleton,…

Axial skeleton

Organization of Human Skeleton: The human skeleton is divided into two main parts: the axial skeleton and the appendicular skeleton, which…

Appendicular skeleton

Organization of Appendicular Skeleton: The appendicular skeleton consists of the bones of the upper and lower limbs and the girdles…

Joints and muscle movement

Types of Joints and Their Functions: Joints are points where two or more bones meet, allowing movement and providing mechanical support to…

Ecosystem components

Environmental Biology is the scientific study of the relationships between organisms and their environment, including the interactions…

Ecosystem processes

Niche and Habitat: A niche is the specific role or position that an organism occupies within an ecosystem, including its interactions with…

World biomes

Biomes as Major Ecological Units: A biome is a large geographical area characterized by distinct climate, vegetation, and animal life,…

Ecosystems of Sri Lanka

Ecosystem Diversity in Sri Lanka: Ecosystem diversity refers to the variety of different ecosystems found within a geographical region,…

Biodiversity and threats

Biodiversity and Its Components: Biodiversity refers to the variety of life forms at all levels of biological organization, including…

Global environmental problems

Global Warming and Climate Change: Global warming refers to the long-term increase in Earth's average surface temperature due to human…

Biodiversity and environmental conservation

In-situ and Ex-situ Conservation: In-situ conservation refers to the conservation of species in their natural habitats, while ex-situ…

Microorganisms as pathogens

Normal Microbiota: The collection of microorganisms that normally inhabit various parts of the human body without causing disease under…

Microbial control methods

Disinfectants and Antiseptics: Chemical agents used to control microbial populations on surfaces and living tissues respectively.

Use of microorganisms in industry and agriculture

Industrial Applications of Microorganisms: The use of microorganisms in industrial processes to produce commercial products through their…

Soil microorganisms and soil health

Soil as a Microbial Habitat: Soil provides a complex physical and chemical environment that serves as a natural medium for the growth and…

Microbiology in water and waste management

Water Contamination and Public Health: Water contamination refers to the presence of harmful microorganisms, chemicals, or other substances…

Recycling of solid wastes

Solid waste management refers to the systematic collection, transportation, processing, recycling, and disposal of solid waste materials in…

Microbes and food spoilage

Food Spoilage by Microorganisms: Food spoilage refers to the undesirable changes in food quality caused by the growth and metabolic…

Ornamental fish culture

Aquaculture and Its Importance: Aquaculture is the farming of aquatic organisms such as fish, crustaceans, mollusks, and aquatic plants…

Horticultural practices

Nursery management refers to the systematic cultivation and care of young plants (seedlings) in a controlled environment before they are…

Vector-borne diseases

Vector-Borne Diseases: Diseases transmitted to humans or animals by living organisms (vectors) that carry pathogens from one host to…

Food preservation and postharvest losses

Food Preservation Principles: Food preservation involves applying scientific methods to prevent food spoilage, maintain nutritional value,…

Emerging biotechnologies

Nanotechnology in Biology: Nanotechnology is the manipulation of matter on an atomic, molecular, and supramolecular scale, typically…