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IB Biology Topic D4.2 Sustainability and Change… | RevisionDojo

IB
D4.2 Sustainability and change

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

D4.2B Keystone species, sustainable harvesting, agriculture and eutrophication

Key Definitions

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Subtopics and learning objectives

D4.2.5 Role of keystone species in the stability of ecosystems

D4.2A Ecosystem stability, tipping points and modelling

D4.2C Biomagnification, plastic pollution and rewilding

Keystone Species: A Small Population With Outsized Power

A keystone species has an effect on its ecosystem far greater than its abundance or biomass would suggest.
Removing one usually triggers cascading effects that destabilise the whole ecosystem.

Three Traits Define a Keystone Species

Disproportionate influence
1. Its impact outweighs its biomass or population size.
Regulates ecosystem dynamics
1. It controls dominant species and lets biodiversity flourish.
Its removal sparks a trophic cascade
1. Losing it reshapes the entire food web.

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D4.2.5 Role of keystone species in the stability of ecosystems
D4.2.6 Assessing sustainability of resource harvesting from natural ecosystems
D4.2.7 Factors affecting the sustainability of agriculture
D4.2.8 Eutrophication of aquatic and marine ecosystems due to leaching

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