Master Topic 2 of the updated IB Environmental Systems and Societies (ESS) course with this comprehensive student workbook, fully aligned to the syllabus for first examinations in 2026.

This workbook helps students build a strong understanding of ecology, from the organization of life in the biosphere to the global patterns that shape ecosystems across the planet. Through guided notes, structured practice activities, exam-style questions, and a complete answer key, students develop the knowledge and skills needed to succeed in IB ESS. Designed for both Standard Level (SL) and Higher Level (HL) students, it provides a clear pathway through the most important concepts, terminology, and assessment objectives in Topic 2.

Whether used in the classroom, for homework, revision, independent study, or exam preparation, this workbook encourages active learning and helps students develop the analytical and evaluation skills required for success in IB ESS.

What You’ll Learn

Topic 2.1: Ecosystems and Ecology

Students explore:

The organization of life from individuals and populations to communities and ecosystems
The biological species concept and why it can be challenging to apply
Classification of organisms and the tools taxonomists use, including DNA barcoding
Abiotic and biotic factors and how they determine species distribution
The concept of ecological niche, including fundamental and realized niches
Types of population interactions, including predation, parasitism, mutualism, and competition
Keystone species and their role in maintaining ecosystem structure
Population sampling techniques, including the mark-recapture method and the Lincoln index
Planetary boundaries and the concept of ecological tipping points
r- and K-selected species and life history strategies (HL)

Topic 2.2: Energy and Biomass in Ecosystems

Students investigate:

How ecosystems are sustained by inputs of energy and matter
Photosynthesis and cellular respiration as the foundation of energy flow
Producers, consumers, detritivores, saprotrophs, and decomposers
Food chains, food webs, and trophic levels
Gross productivity and net productivity
Ecological pyramids: numbers, biomass, and energy
Bioaccumulation and biomagnification of persistent pollutants
The environmental impacts of microplastics across trophic levels

Topic 2.3: Biogeochemical Cycles

Students examine:

How carbon, nitrogen, and other elements cycle through biotic and abiotic stores
The distinction between stores, sinks, and sources in biogeochemical cycles
Carbon sequestration and the role of ecosystems as carbon sinks or sources
•The impacts of fossil fuel combustion on the carbon cycle
Ocean acidification as a consequence of rising atmospheric carbon dioxide
The nitrogen cycle, including nitrogen fixation, nitrification, and denitrification
Eutrophication and the environmental consequences of nitrogen and phosphorus pollution
Human disruption of natural cycling rates and international efforts to manage nutrient use

Topic 2.4: Climate and Biomes

Students investigate:

The difference between climate and weather
How temperature, precipitation, and insolation determine biome distribution
Major terrestrial and aquatic biomes and their limiting factors
The tricellular model of atmospheric circulation, including Hadley, Ferrel, and polar cells
Ocean currents and their influence on regional climates
El Niño and La Niña events and their global ecological consequences
The relationship between sea surface temperature and tropical cyclone intensity
How climate change is shifting biome boundaries and disrupting phenological patterns

Topic 2.5: Zonation, Succession, and Change in Ecosystems

Students examine:

Zonation and how environmental gradients drive community change across space
Primary and secondary succession and the progression of seral communities
The role of pioneer species in initiating succession
Climax communities and the debate over the Vera wood-pasture hypothesis
Ecosystem resilience and the concept of alternative stable states
How human activity can divert succession and create plagioclimax communities
Productivity patterns and how they change across successional stages (HL)

What’s Included

✔ Coverage of all Topic 2 syllabus statements for SL and HL

✔ Content aligned to the updated IB ESS syllabus (first examinations 2026)

✔ Separate sections for SL and HL content

✔ Key vocabulary tables with space for definitions and named examples

✔ Guided notes that mirror IB assessment language and command terms

✔ Structured practice activities including data analysis and diagram completion

✔ Exam-style short-answer and extended-response questions

✔ Critical-thinking opportunities aligned with Assessment Objectives AO2 and AO3

✔ Complete answer key included

Why Students Love This Workbook

Unlike traditional revision notes, this workbook actively engages students in the learning process. The guided activities are designed around the language and command terms used in IB assessments, helping learners build confidence while developing the skills required to analyze, explain, compare, evaluate, and justify environmental concepts.

Students can use the workbook throughout the course or as a focused revision tool before assessments.

Ideal For

IB Environmental Systems and Societies students
Standard Level (SL) students
Higher Level (HL) students
IB teachers seeking ready-to-use classroom resources
Homeschool learners following the IB curriculum
Students preparing for quizzes, tests, and final examinations

Product Details

Format: Digital PDF Download

Course: IB Environmental Systems and Societies (ESS)

Topic: Topic 2 – Ecology

Level: SL and HL

Answer Key: Included

Author: Bradley M Kremer

Publisher: IB ESSentials

Syllabus Alignment: First Examinations 2026

Important Information

This resource is independently produced and is not endorsed by or affiliated with the International Baccalaureate Organization (IBO).

Your purchase includes a license for individual educational use unless otherwise specified.

Explore additional IB ESS workbooks, revision resources, study guides, and teaching materials at mrkremerscience.com and ibessentials.org.

IB ESS Topic 2 – Ecology

IB ESS Topic 2 Student Workbook: Ecology (SL/HL, 2026) | PDF with Answer Key