Topic 1: Foundation

1.1 Perspectives

1.2 Systems

1.3 Sustainability

Topic 2: Ecology

2.1 Individuals, populations, communities, and ecosystems

2.2 Energy and biomass in ecosystems

2.2.1—Ecosystem sustenance

2.2.2—First law of thermodynamics

2.2.3—Energy and matter transformation

2.2.4—Photosynthesis

2.2.5—Producers

2.2.6—Cellular respiration

2.2.7—Heat generation

2.2.8—Second law and energy loss

2.2.9—Consumer energy sources

2.2.10—Producers and food chains

2.2.11—Food chains and trophic levels

2.2.12—Food-chain energy losses

2.2.13—Gross and net productivity

2.2.14—Limits on trophic levels

2.2.15—Food webs

2.2.16—Biomass measurement

2.2.17—Ecological pyramids

2.2.18—Non-biodegradable pollutants

2.2.19—Microplastics

2.2.20—Human activity impacts

2.2.21 (HL)—Autotrophs vs. heterotrophs

2.2.22 (HL)—Photoautotrophs and chemoautotrophs

2.2.23 (HL)—Primary productivity

2.2.24 (HL)—Secondary productivity

2.2.25 (HL)—NPP and food chains

2.2.26 (HL)—Maximum sustainable yield

2.2.27 (HL)—Lower trophic level yields

2.2.28 (HL)—Ecological efficiency

2.2.29 (HL)—Entropy in ecosystems

2.3 Biogeochemical cycles

2.4 Climate and biomes

2.5 Zonation, succession and change

Topic 3: Biodiversity and conservation

3.1 Biodiversity and evolution

3.2 Human impact on biodiversity

3.3 Conservation and regeneration

Topic 4: Water

4.1 Water systems

4.2 Water access, use and security

4.3 Aquatic food production systems

4.4 Water pollution

Topic 5: Land

5.1 Soil

5.2 Agriculture and food

Topic 6: Atmosphere and climate change

6.1 Introduction to the atmosphere

6.2 Climate change—causes and impacts

6.3 Climate change—mitigation and adaptation

6.4 Stratospheric ozone

Topic 7: Natural resources

7.1 Natural resources—uses and management

7.2 Energy sources—uses and management

7.3 Solid waste

Topic 8: Human populations and urban systems

8.1 Human populations

8.2 Urban systems and urban planning

8.3 Urban air pollution

HL.a Environmental law

HL.b Environmental economics

HL.c Environmental ethics

IB ESS HL 2.2.22 (HL)—Photoautotrophs and chemoautotrophs Question Bank

• Photoautotrophs use light as an external energy source in photosynthesis

• Chemoautotrophs use exothermic inorganic chemical reactions as an external energy source in chemosynthesis

• Chemoautotrophs exist in a variety of ecosystems, especially those where there is little or no light

• In such ecosystems, chemoautotrophs are the principal source of energy to sustain food webs

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