IB ESS · Unit 2 of 8

Unit 2: Ecology

Unit 2 of IB Environmental Systems and Societies covers Ecology. This unit contains 8 topics and 28 sub-topics. Below you'll find free study notes, flashcards, and exam preparation resources for every topic in this unit.

8 topics28 sub-topics

ESS Flashcards Exam technique guide

What Unit 2 covers

Unit 2 covers ecological principles including species interactions, energy flows through food chains, nutrient cycling, and the structure of ecosystems. Students learn to analyse trophic levels, calculate productivity, and evaluate human impacts on ecological systems — all frequently tested in IB ESS Paper 1 and Paper 2.

Topics in Unit 2

2.1

Species, populations

3 sub-topics

2.2

Communities and ecosystems

3 sub-topics

2.3

Habitat, niche and interactions

2 sub-topics

2.4

Food chains & webs and trophic levels

2 sub-topics

2.5

Flows of energy and matter

4 sub-topics

2.6

Human impacts

8 sub-topics

2.7

Biogeochemical cycles

3 sub-topics

2.8

Biomes, zonation, succession

3 sub-topics

Study tip: Work through the topics in order — each builds on concepts from the one before. Start with notes, then reinforce with flashcards and practice questions.

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