MATSEC SEC Environmental Studies cheat sheet

Environmental Studies - Core Reference

• Ecosystem = community of organisms plus the non-living environment interacting as a functional unit; inputs are solar energy, water, nutrients; outputs are heat, biomass, waste.

• Energy flows one way through trophic levels (producer → primary consumer → secondary consumer); only roughly 10% of energy passes to the next level, so food chains rarely exceed 4–5 links.

• Matter cycles (biogeochemical cycles) - carbon, nitrogen, phosphorus, water - unlike energy, which cannot be recycled once dissipated as heat.

• Photosynthesis: 6CO2 + 6H2O + light → C6H12O6 + 6O2; respiration reverses it, releasing stored energy as ATP plus heat.

• Population growth: exponential model dN/dt = rN; logistic model dN/dt = rN(K − N)/K, where K is carrying capacity; growth slows as N approaches K.

• Biotic potential vs environmental resistance: r-selected species (many small offspring, little care) versus K-selected species (few offspring, high parental investment).

• Biodiversity has three levels: genetic, species and ecosystem diversity; hotspots are areas of high endemism under high habitat-loss pressure.

• Pollution categories: point source (identifiable outlet, e.g. a pipe) versus non-point source (diffuse runoff); biodegradable versus persistent pollutants (e.g. DDT, PCBs, heavy metals).

• EIA decision rule: screen → scope → baseline study → predict impacts → mitigation → monitoring; public consultation is a required stage in most jurisdictions.