Class 11 Biology: Diversity & Structure

Definition of Biodiversity: Variety of life forms in a given habitat.
Taxonomy: Science of classification; includes levels: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
Binomial Nomenclature: Two-part naming system (Genus + Species).
Five Kingdom Classification: Monera, Protista, Fungi, Plantae, Animalia.

Tissues: Group of cells performing a specific function.
- Animal Tissues: Epithelial, Connective, Muscular, Nervous.
- Plant Tissues: Meristematic (growth) and Permanent (mature).
Organ Systems: Groups of organs working together (e.g., digestive, respiratory).

Cell Theory: All living organisms are composed of cells; cells are the basic unit of life.
Types of Cells: Prokaryotic (no nucleus) and Eukaryotic (nucleus present).
Cell Organelles:
- Nucleus: Control center of the cell.
- Mitochondria: Powerhouse, energy production.
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum: Protein and lipid synthesis.
- Golgi Apparatus: Packaging and distribution of proteins.
- Plasma Membrane: Regulates entry and exit of substances.

Photosynthesis: Process by which plants convert light energy to chemical energy.
- Chlorophyll: Green pigment involved in photosynthesis.
- Equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.
Transpiration: Loss of water vapor from plant surfaces.
Plant Hormones:
- Auxins: Promote cell elongation.
- Gibberellins: Stimulate growth and flowering.
- Cytokinins: Promote cell division.

Digestive System: Breaks down food; major organs include mouth, stomach, intestines.
Respiratory System: Involves gas exchange (O₂ and CO₂); key structures include lungs, diaphragm.
Circulatory System: Transports blood, nutrients, and gases; consists of heart, blood vessels, and blood.
Nervous System: Controls body functions; central (brain, spinal cord) and peripheral (nerves) components.

Types of Reproduction:
- Asexual: Single organism; e.g., budding, binary fission.
- Sexual: Involves two organisms; gamete formation.
Human Reproductive System: Male (testes, sperm) and Female (ovaries, eggs).
Menstrual Cycle: Monthly cycle in females involving ovulation and menstruation.

Mendelian Genetics: Laws of inheritance established by Gregor Mendel.
- Law of Segregation: Alleles separate during gamete formation.
- Law of Independent Assortment: Different traits segregate independently.
Genotype vs. Phenotype: Genotype (genetic makeup), Phenotype (physical expression).

Theory of Evolution: Process by which species change over time through natural selection.
Natural Selection: Survival of the fittest; organisms best adapted to their environment survive.
Speciation: Formation of new and distinct species.

These notes encapsulate the essential topics and concepts in Class 11 Biology, providing a solid foundation for further study.

Biodiversity refers to the variety of life forms within a specific habitat, emphasizing the richness of species.
Taxonomy is the scientific discipline of classifying living organisms into hierarchical categories: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
Binomial nomenclature provides a standardized two-part naming system for species, consisting of the Genus and Species names.
The five kingdom classification system includes Monera (unicellular organisms), Protista (simple eukaryotes), Fungi (decomposers), Plantae (plants), and Animalia (animals).

Tissues are defined as groups of cells that work together to perform specific functions.
Four types of animal tissues include:
- Epithelial tissue (covers surfaces),
- Connective tissue (provides support and binds other tissues),
- Muscular tissue (facilitates movement),
- Nervous tissue (transmits impulses).
Plant tissues are categorized into:
- Meristematic tissues (responsible for growth),
- Permanent tissues (mature and specialized).
Organ systems are formed by groups of organs that collaboratively perform vital biological functions, such as the digestive and respiratory systems.

The cell theory posits that all living organisms are composed of cells, which are the fundamental units of life.
Cells fall into two main categories:
- Prokaryotic cells, which lack a nucleus,
- Eukaryotic cells, which contain a defined nucleus.
Major cell organelles include:
- Nucleus: Acts as the control center of the cell.
- Mitochondria: Known as the "powerhouse" for energy production.
- Ribosomes: Sites for protein synthesis.
- Endoplasmic Reticulum: Involved in synthesizing proteins and lipids.
- Golgi Apparatus: Responsible for packaging and distributing proteins.
- Plasma Membrane: Controls the entry and exit of substances.

Photosynthesis is the biochemical process that converts light energy into chemical energy stored in glucose.
Chlorophyll is the green pigment crucial for capturing light energy during photosynthesis.
The photosynthesis equation is represented as: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.
Transpiration is the process of water vapor loss from plant surfaces, crucial for nutrient transport and temperature regulation.
Plant hormones include:
- Auxins: Stimulate cell elongation,
- Gibberellins: Promote growth and flowering,
- Cytokinins: Encourage cell division.

The digestive system is responsible for breaking down food; key organs include the mouth, stomach, and intestines.
The respiratory system facilitates gas exchange, primarily occurring in the lungs, assisted by the diaphragm.
The circulatory system transports blood, nutrients, and gases, comprising the heart, blood vessels, and blood.
The nervous system regulates bodily functions and is divided into:
- Central nervous system (brain and spinal cord),
- Peripheral nervous system (nerves throughout the body).

Reproduction can be categorized into:
- Asexual reproduction: Involves a single organism (e.g., budding, binary fission).
- Sexual reproduction: Involves two organisms and the formation of gametes.
The human reproductive system includes male components (testes producing sperm) and female components (ovaries producing eggs).
The menstrual cycle is a recurring monthly process in females, characterized by ovulation and menstruation.

Mendelian genetics established foundational laws of inheritance through the works of Gregor Mendel.
The Law of Segregation states that allele pairs separate during gamete formation, resulting in offspring with different traits.
The Law of Independent Assortment explains how different traits are inherited independently from one another.
Genotype refers to the genetic makeup of an organism, while phenotype describes the observable physical traits expressed.

The theory of evolution explains how species evolve over time through the process of natural selection.
Natural selection operates on the principle of "survival of the fittest," where organisms best suited to their environment survive and reproduce.
Speciation is the process that leads to the formation of new and distinct species.