Basic Concepts in Biology

Definition: Biology is the scientific study of life and living organisms, encompassing their structure, function, growth, evolution, distribution, and taxonomy.

Metabolism: The sum of all chemical reactions occurring in an organism.
- Catabolism: Breakdown of molecules to obtain energy.
- Anabolism: Synthesis of compounds necessary for cell maintenance and growth.
Homeostasis: The ability of organisms to maintain a stable internal environment despite changes in external conditions.
Reproduction: The process by which organisms produce new individuals.
- Asexual Reproduction: Offspring arise from a single organism (e.g., binary fission, budding).
- Sexual Reproduction: Involves the fusion of gametes from two parents.

Cell Theory:
- All living organisms are made of cells.
- The cell is the basic unit of life.
- All cells arise from pre-existing cells.
Types of Cells:
- Prokaryotic Cells: Simple, no nucleus or membrane-bound organelles (e.g., bacteria).
- Eukaryotic Cells: Complex, with a nucleus and membrane-bound organelles (e.g., plant and animal cells).

DNA Structure: Double helix made of nucleotides (adenine, thymine, cytosine, guanine).
Gene: A segment of DNA that codes for a protein.
Inheritance: Transmission of genetic information from parents to offspring.
- Mendelian Genetics: Study of inheritance patterns (dominant and recessive traits).

Theory of Evolution: Proposed by Charles Darwin; states that species evolve over time through natural selection.
Natural Selection: Process where organisms with favorable traits survive and reproduce.
Speciation: The formation of new and distinct species through evolution.

Ecosystem: A community of living organisms and their physical environment.
Biomes: Large geographical areas with distinct climates and organisms (e.g., deserts, forests).
Food Chain/Web: The flow of energy and nutrients through an ecosystem, showing who eats whom.

Taxonomy: The science of classifying organisms into groups.
- Hierarchical Categories:
  1. Domain
  2. Kingdom
  3. Phylum
  4. Class
  5. Order
  6. Family
  7. Genus
  8. Species

Organ Systems: Groups of organs that perform specific functions.
- Circulatory System: Transports blood and nutrients.
- Respiratory System: Facilitates gas exchange.
- Digestive System: Breaks down food and absorbs nutrients.

Photosynthesis: Process by which plants convert sunlight into energy (glucose), using carbon dioxide and water.
Plant Structures:
- Roots: Anchor plants and absorb nutrients/water.
- Stems: Support plant structure and transport materials.
- Leaves: Main site of photosynthesis.

Microscopy: Use of microscopes to observe small structures.
DNA Sequencing: Determining the order of nucleotides in DNA.
PCR (Polymerase Chain Reaction): Technique to amplify DNA segments for analysis.

Definition: Biology is the scientific study of living organisms, covering their structure, function, growth, evolution, distribution, and classification.

Metabolism: The sum of all chemical reactions within an organism.
- Catabolism: Breakdown of molecules to release energy.
- Anabolism: Synthesis of molecules for cell growth and maintenance.
Homeostasis: Maintaining a stable internal environment despite external changes.
Reproduction: The process of creating new individuals.
- Asexual Reproduction: Offspring from a single parent (e.g., binary fission, budding).
- Sexual Reproduction: Fusion of gametes from two parents.

Cell Theory:
- All living organisms are composed of cells.
- The cell is the fundamental unit of life.
- All cells arise from pre-existing cells.
Cell Types:
- Prokaryotic Cells: Simple, lack a nucleus and membrane-bound organelles (e.g., bacteria).
- Eukaryotic Cells: Complex, possess a nucleus and membrane-bound organelles (e.g., plant and animal cells).

DNA Structure: A double helix composed of nucleotides (adenine, thymine, cytosine, guanine).
Gene: A DNA segment coding for a specific protein.
Inheritance: Passing genetic information from parents to offspring.
Mendelian Genetics: The study of inheritance patterns (dominant and recessive traits).

Theory of Evolution: Proposed by Charles Darwin, stating that species evolve over time through natural selection.
Natural Selection: Organisms with favorable traits survive and reproduce more successfully.
Speciation: The formation of new and distinct species through evolution.

Ecosystem: A community of living organisms and their physical environment.
Biomes: Large geographic areas with distinct climates and organisms (e.g., deserts, forests).
Food Chain/Web: The flow of energy and nutrients through an ecosystem, showing predator-prey relationships.

Taxonomy: The science of classifying organisms into groups.
Hierarchical Categories:
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species

Organ Systems: Groups of organs working together for specific functions.
- Circulatory System: Transports blood and nutrients.
- Respiratory System: Facilitates gas exchange.
- Digestive System: Breaks down food and absorbs nutrients.

Photosynthesis: Plants convert sunlight into energy (glucose) using carbon dioxide and water.
Plant Structures:
- Roots: Anchor plants and absorb nutrients/water.
- Stems: Support plant structure and transport materials.
- Leaves: The primary site of photosynthesis.