Mycorrhizae play a vital role in terrestrial ecosystems by facilitating nutrient uptake. Which statement correctly describes the ecological relationship between mycorrhizal fungi and their host plants?
It is a mutualistic relationship in which the fungus increases the effective surface area of the root system for the absorption of water and mineral ions, while the plant provides the fungus with organic compounds such as carbohydrates.
It is a commensal relationship in which the fungus benefits by obtaining amino acids and sucrose from the root cortical cells, while the host plant is completely unaffected.
It is a saprobiotic relationship in which the fungus secretes extracellular enzymes to decompose the dead outer layer of root cells, releasing phosphate ions that are then absorbed by active transport.
It is a mutualistic relationship in which the plant increases its transpiration rate to supply water to the hyphae, while the fungus fixes atmospheric nitrogen gas directly into ammonium ions for the plant.
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.