A marine biology expedition investigates a hydrothermal vent on the mid-ocean ridge. They measure abiotic parameters such as a hydrostatic pressure of 25 MPa, temperatures of 350∘C350^{\circ}\text{C}350∘C, and high concentrations of dissolved hydrogen sulfide. They also document the biotic components, including chemosynthetic bacteria, giant tube worms (Riftia pachyptila), and vent crabs (Bythograea thermydron).
Which term correctly defines the functional unit comprised of both these physical-chemical factors and all the interacting populations of organisms?
A community
An ecosystem
A habitat
An ecological niche
67 exam-style questions on OCR GCSE Biology 4.1 Ecosystems, covering 4.1.1 Cycling of materials in ecosystems, 4.1.2 Microorganisms in cycling materials, 4.1.3 The carbon and water cycles, 4.1.4 Factors affecting decomposition, 4.1.5 Levels of organisation in an ecosystem, 4.1.6 Abiotic and biotic factors affecting communities, 4.1.7 Interdependence and competition, 4.1.8 Trophic levels, 4.1.9 Pyramids of biomass, and 4.1.10 Efficiency of biomass transfers. Each one has a worked solution and a mark scheme showing where the marks go.