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A1.1 Water

A1.2 Nucleic acids

A2.1 Origins of cells (HL)

A2.2 Cell structure

A2.3 Viruses (HL)

A3.1 Diversity of organisms

A3.2 Classification and cladistics (HL)

A4.1 Evolution and speciation

A4.2 Conservation of biodiversity

B1.1 Carbohydrates and lipids

B1.2 Proteins

B2.1 Membranes and membrane transport

B2.2 Organelles and compartmentalization

B2.3 Cell specialization

B3.1 Gas exchange

B3.2 Transport

B3.3 Muscle and motility (HL)

B4.1 Adaptation to environment

B4.2 Ecological niches

C1.1 Enzymes and metabolism

C1.2 Cell respiration

C1.3 Photosynthesis

C2.1 Chemical signalling (HL)

C2.2 Neural signalling

C3.1 Integration of body systems

C3.2 Defense against disease

C4.1 Populations and communities

C4.2 Transfer of energy and matter

D1.1 DNA replication

D1.2 Protein synthesis

D1.3 Mutations and gene editing

D2.1 Cell and nuclear division

D2.2 Gene expression (HL)

D2.3 Water potential

D3.1 Reproduction

D3.2 Inheritance

D3.3 Homeostasis

D4.1 Natural selection

D4.2 Sustainability and change

D4.3 Climate change

IB Biology Topic C4.1: Populations and Communities Lessons

Written by IB Experts

This lesson delivers structured, step-by-step lessons that guide students through every part of the IB Biology syllabus for C4.1 Populations and communities. These lessons simplify complex ideas like molecular biology, evolutionary mechanisms, and homeostasis, while worked examples show how to approach IB-style questions.

Designed for both HL and SL learners, RevisionDojo lessons ensure students not only understand the theory but also know how to apply it in IB Paper exam situations.

With clear explanations, active learning checks, and a syllabus-first design, RevisionDojo makes revision less overwhelming and more effective.

C4.1.1 Populations

C4.1.2 Estimation of population size by random sampling

C4.1.3 Random quadrat sampling to estimate population size for sessile organisms

C4.1.4 Capture–mark–release–recapture and the Lincoln index

C4.1.5 Carrying capacity and competition for limited resources

C4.1.6 Negative feedback control of population size by density-dependent factors

C4.1.7 Population growth curves

C4.1.8 Modelling of the sigmoid population growth curve

C4.1.9 Competition versus cooperation in intraspecific relationships

C4.1.10 A community as all of the interacting organisms in an ecosystem

C4.1.11 Herbivory, predation, interspecific competition, mutualism, parasitism and pathogenicity

C4.1.12 Mutualism as an interspecific relationship that benefits both species

C4.1.13 Resource competition between endemic and invasive species

C4.1.14 Tests for interspecific competition

C4.1.15 Use of the chi-squared test for association between two species

C4.1.16 Predator–prey relationships

C4.1.17 Top-down and bottom-up control of populations in communities

C4.1.18 Allelopathy and secretion of antibiotics

Written by IB Experts

This lesson delivers structured, step-by-step lessons that guide students through every part of the IB Biology syllabus for C4.1 Populations and communities. These lessons simplify complex ideas like molecular biology, evolutionary mechanisms, and homeostasis, while worked examples show how to approach IB-style questions.

Designed for both HL and SL learners, RevisionDojo lessons ensure students not only understand the theory but also know how to apply it in IB Paper exam situations.

With clear explanations, active learning checks, and a syllabus-first design, RevisionDojo makes revision less overwhelming and more effective.

C4.1.1 Populations

C4.1.2 Estimation of population size by random sampling

C4.1.3 Random quadrat sampling to estimate population size for sessile organisms

C4.1.4 Capture–mark–release–recapture and the Lincoln index

C4.1.5 Carrying capacity and competition for limited resources

C4.1.6 Negative feedback control of population size by density-dependent factors

C4.1.7 Population growth curves

C4.1.8 Modelling of the sigmoid population growth curve

C4.1.9 Competition versus cooperation in intraspecific relationships

C4.1.10 A community as all of the interacting organisms in an ecosystem

C4.1.11 Herbivory, predation, interspecific competition, mutualism, parasitism and pathogenicity

C4.1.12 Mutualism as an interspecific relationship that benefits both species

C4.1.13 Resource competition between endemic and invasive species

C4.1.14 Tests for interspecific competition

C4.1.15 Use of the chi-squared test for association between two species

C4.1.16 Predator–prey relationships

C4.1.17 Top-down and bottom-up control of populations in communities

C4.1.18 Allelopathy and secretion of antibiotics

IB Biology Topic C4.1: Populations and Communities Lessons

A - Unity and Diversity

B - Form and Function

C - Interaction and Interdependence

D - Continuity and Change

IB Biology Topic C4.1: Populations and Communities Lessons

Lessons for C4.1 Populations and communities - IB

Lessons for C4.1 Populations and communities - IB

A - Unity and Diversity

B - Form and Function

C - Interaction and Interdependence

D - Continuity and Change

IB Biology Topic C4.1: Populations and Communities Lessons