B10: Ecology, Ecosystems, Nutrient Cycles and Sampling
Official Cambridge & Imperial ESAT specification requirements for Ecology, Ecosystems, Nutrient Cycles and Sampling on the Biology paper. Understand the syllabus boundaries, spot distractor traps engineered by examiners, and master the 2-step Sub-90 shortcuts that compress solve time well below the 88.8-second cutoff.
Official Syllabus Subtopics
Requirements specified in the UAT-UK framework
- 1Levels of ecological organisation: individual, population, community, ecosystem, biome
- 2Trophic levels, food webs, and the 10% trophic energy transfer efficiency rule
- 3Pyramids of numbers, pyramids of biomass, and pyramids of energy transferred over time
- 4Carbon cycle: photosynthesis, respiration, combustion, and decomposition
- 5Nitrogen cycle: nitrogen fixation (Rhizobium), nitrification (Nitrosomonas, Nitrobacter), assimilation, and denitrification (anaerobic waterlogged soil)
- 6Eutrophication sequence: fertiliser runoff, algal bloom, light blockage, submerged plant death, bacterial aerobic decomposition, oxygen depletion, fish suffocation
- 7Ecological sampling methods: random quadrat sampling, systematic belt transects, and mark-release-recapture (Lincoln Index: N = (M × C) / R)
Sub-90 Exam Speed Tips
How top candidates solve this spec under the 88.8s clock
Pyramids of numbers and biomass can be inverted (e.g. parasites on an oak tree), but pyramids of energy transferred per unit time are ALWAYS strictly upright.
Denitrifying bacteria convert nitrates back into nitrogen gas under anaerobic conditions (waterlogged soils), depleting soil fertility.
Examiners engineer distractor options using common algebraic expansions and sign slips. Always test structural ratios or invariants before calculating arithmetic values.
Tested Topics in Specification B10
Master the individual question patterns and Sub-90 shortcuts for this specification.
Carbon/Nitrogen Cycle Bacteria, Trophic Energy Efficiency & Eutrophication Cascade Sequences
Nitrogen bacteria 3-way check: N2 -> NH4+ (Nitrogen-fixing, root nodules/lightning); NH4+ -> NO2- -> NO3- (Nitrifying, aerobic); NO3- -> N2 (Denitrifying, anaerobic waterlogged soil). Eutrophication O2 drop is caused by AEROBIC DECOMPOSERS.
Belt Transect Kite Diagrams, Quadrat/Lincoln Index Population Sampling & Sigmoid Growth Curves
Quadrat scaling: Total Population = (Mean per quadrat) × (Total Area / Quadrat Area)—for a 0.5 m × 0.5 m quadrat, Area = 0.25 m² so multiply per-quadrat mean by 4 to get density per m²! Lincoln index: N = (n1 × n2) / m2.
Ready to Master Specification B10 Under Exam Conditions?
Practice timed questions under the authentic Pearson VUE interface with live split stopwatch pacing, dry-wipe scratchpad, and distractor forensics.