Biology HL 2025

Unity & Diversity

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Unity & Diversity | IB Biology
IB BIOLOGY

Unity & Diversity

Common Origins, Endless Variety
Discover how all life shares fundamental principles while expressing incredible diversity through evolution, cellular structures, and biological classification.

🌊 Choose Your Topic

Select a topic below to access comprehensive study materials

💧

Fundamental Life Processes

Study the basic building blocks and processes that unite all living organisms.

Water Nucleic Acids Origins of Cells Cell Structure
PDF
Water
PDF
Nucleic Acids
PDF
Origins of Cells
PDF
Cell Structure
🦋

Biological Diversity

Explore the incredible variety of life forms and how scientists organize and classify them.

Diversity of Organisms Classification Cladistics Viruses
PDF
Diversity of Organisms
PDF
Classification & Cladistics
PDF
Viruses
🌿

Evolution & Conservation

Understand how diversity arose through evolution and how we protect biodiversity today.

Evolution Speciation Conservation Biodiversity
PDF
Evolution & Speciation
PDF
Conservation of Biodiversity

📊 Unity & Diversity Overview

Complete collection of foundational biology materials

9
PDF Resources
3
Topic Categories
HL
Higher Level
2025
Curriculum

⚖️ Unity vs Diversity in Biology

Understanding how life maintains common principles while expressing endless variety

🔗 Unity – What Connects All Life

💧
Water as Universal Solvent

All life depends on water’s unique properties

🧬
DNA & RNA Information Storage

Universal genetic code across all organisms

🔬
Cellular Organization

All life is made of cells with membranes

⚡
Energy Metabolism

Similar biochemical pathways in all organisms

🌈 Diversity – What Makes Life Unique

🦠
Prokaryotes vs Eukaryotes

Different cellular organizations and complexity

🌱
Autotrophs vs Heterotrophs

Different strategies for obtaining energy

🧪
Specialization & Adaptation

Organisms adapt to specific environments

🔄
Evolutionary Divergence

Common ancestors lead to different lineages

🏛️ Biological Classification

How we organize life’s diversity from broad categories to specific species

Domain
Bacteria, Archaea, Eukarya
Kingdom
Animalia, Plantae, Fungi, etc.
Phylum
Chordata, Arthropoda, etc.
Class
Mammalia, Insecta, etc.
Order
Primates, Lepidoptera, etc.
Family
Hominidae, Felidae, etc.
Genus
Homo, Felis, etc.
Species
sapiens, catus, etc.

Interaction & Interdependence

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Interaction & Interdependence | IB Biology
IB BIOLOGY

Interaction & Interdependence

Connected Systems
Explore how organisms interact with each other and their environment through metabolic processes, signalling systems, and ecological relationships.

🌿 Choose Your Topic

Select a topic below to access comprehensive study materials

⚡

Energy & Metabolism

Study the fundamental processes of energy conversion and metabolic pathways that sustain life.

Photosynthesis Cell Respiration Enzymes & Metabolism Energy Transfer
PDF
Photosynthesis
PDF
Cell Respiration
PDF
Enzymes & Metabolism
PDF
Transfer of Energy & Matter
📡

Communication & Signalling

Understand how organisms communicate through chemical and neural signalling systems.

Neural Signalling Chemical Signalling System Integration Defense Systems
PDF
Neural Signalling
PDF
Chemical Signalling
PDF
Integration of Body Systems
PDF
Defence Against Disease
🌍

Ecological Interactions

Explore how populations and communities interact within ecosystems and environmental networks.

Populations Communities Ecosystem Dynamics
PDF
Populations & Communities

📊 Interaction & Interdependence Overview

Complete collection of biological interaction materials

9
PDF Resources
3
Topic Categories
HL
Higher Level
2025
Curriculum

🔄 Key Biological Processes

Understanding how organisms interact through fundamental life processes

☀️

Energy Flow

From photosynthesis to respiration, energy moves through living systems

💬

Information Transfer

Chemical and electrical signals coordinate biological functions

🔗

System Integration

Multiple systems work together to maintain life and respond to change

🛡️

Defense Mechanisms

Organisms protect themselves through immune and behavioral responses

🌱

Population Dynamics

Species interact within communities and shape ecosystem structure

⚗️

Metabolic Networks

Enzymatic pathways connect to form complex biochemical networks

🌐 System Connections

How biological systems connect and depend on each other

1

Molecular Level

Enzymes catalyze metabolic reactions

→
2

Cellular Level

Cells communicate through signaling

→
3

Organism Level

Systems integrate for homeostasis

→
4

Ecosystem Level

Communities interact and exchange energy

Form & Function

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Form & Function | IB Biology
IB BIOLOGY

Form & Function

Structure and Process
Explore how biological structures are perfectly adapted to their functions – from molecular transport to muscle movement and environmental adaptation.

🔬 Choose Your Topic

Select a topic below to access comprehensive study materials

🧬

Molecular & Cellular Structure

Study the fundamental building blocks of life – proteins, carbohydrates, lipids, and cellular organization.

Proteins Carbohydrates & Lipids Organelles Cell Specialisation
PDF
Proteins
PDF
Carbohydrates & Lipids
PDF
Organelles & Compartmentalisation
PDF
Cell Specialisation
🚀

Transport & Movement

Understand how substances move through biological systems and how organisms achieve motion.

Transport Systems Membrane Transport Muscle & Motility Gas Exchange
PDF
Transport
PDF
Membranes & Membrane Transport
PDF
Muscle & Motility
PDF
Gas Exchange
🌍

Environmental Interactions

Explore how organisms adapt to their environments and find their ecological niches.

Environmental Adaptation Ecological Niches
PDF
Adaptation to Environment
PDF
Ecological Niches

📊 Form & Function Overview

Complete collection of structural and functional biology materials

10
PDF Resources
3
Topic Categories
HL
Higher Level
2025
Curriculum

💡 Key Concepts

Understanding how structure relates to function in biological systems

🔗

Structure-Function Relationship

Every biological structure is perfectly adapted to perform its specific function

⚖️

Surface Area to Volume

Size and shape optimizations for efficient transport and exchange

🌊

Transport Mechanisms

Passive and active processes that move substances across membranes

🎯

Specialization

How cells and organisms become specialized for specific roles

Continuity & Change

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Continuity & Change | IB Biology
IB BIOLOGY

Continuity & Change

Stability Through Adaptation
Explore how biological systems maintain stability while adapting to change through homeostasis, reproduction, evolution, and genetic mechanisms.

🔄 Choose Your Topic

Select a topic below to access comprehensive study materials

🧬

Genetic Continuity & Change

Study how genetic information is maintained and modified across generations through replication, expression, and mutation.

DNA Replication Gene Expression Protein Synthesis Mutations & Gene Editing
PDF
DNA Replication
PDF
Gene Expression
PDF
Protein Synthesis
PDF
Mutations & Gene Editing
🌱

Evolutionary Change

Understand how populations change over time through natural selection, inheritance, and reproductive strategies.

Natural Selection Inheritance Reproduction Cell Division
PDF
Natural Selection
PDF
Inheritance
PDF
Reproduction
PDF
Cell & Nuclear Division
⚖️

Stability & Homeostasis

Explore how organisms maintain internal stability while responding to environmental changes and challenges.

Homeostasis Stability & Change Water Potential Climate Change
PDF
Homeostasis
PDF
Stability & Change
PDF
Water Potential
PDF
Climate Change

📊 Continuity & Change Overview

Complete collection of stability and adaptation materials

12
PDF Resources
3
Topic Categories
HL
Higher Level
2025
Curriculum

🔄 The Balance of Life

Understanding how biological systems maintain stability while enabling change

🔒 Continuity – What Stays Stable

🧬
DNA Structure

Double helix maintains genetic information integrity

🏠
Homeostasis

Internal conditions maintained within narrow ranges

👨‍👩‍👧‍👦
Heredity

Traits passed reliably from parents to offspring

🔄
Cell Cycle Control

Precise regulation ensures proper cell division

🌊 Change – What Drives Adaptation

⚡
Mutations

DNA changes create genetic variation for selection

🎯
Natural Selection

Environmental pressures drive evolutionary change

🎭
Gene Expression

Cells change which genes are active in response to signals

🌡️
Environmental Response

Organisms adjust to changing external conditions

⏱️ Timescales of Biological Change

From seconds to millennia – how biological systems respond to change

⚡

Seconds to Minutes

Enzyme Activity – Immediate responses to cellular conditions

Nerve Impulses – Rapid communication and responses

🔬

Hours to Days

Gene Expression – Cells adjust protein production

Homeostatic Regulation – Maintaining internal balance

🌱

Weeks to Years

Development & Growth – Individual organism changes

Seasonal Adaptations – Cyclical environmental responses

🧬

Generations

Genetic Inheritance – Traits passed to offspring

Population Changes – Allele frequencies shift

🦕

Millennia & Beyond

Evolution – Speciation and major adaptations

Climate Change – Long-term environmental shifts

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