Ecology Notes for NEET

Ecosystem and Environmental Issues: Scoring Full Marks

The Ecosystem chapter contributes the highest number of ecology questions and tests energy flow, productivity, decomposition, and ecological succession. Energy flow follows the second law of thermodynamics: only 10 percent of energy transfers from one trophic level to the next. If producers fix 1000 J, primary consumers receive 100 J, secondary consumers 10 J, and tertiary consumers 1 J. This 10 percent rule enables NEET numerical problems asking for energy available at any trophic level. Three types of ecological pyramids exist: pyramid of numbers (can be inverted in tree ecosystem), pyramid of biomass (inverted in aquatic ecosystem with phytoplankton base), and pyramid of energy (never inverted). Nutrient cycling distinguishes gaseous cycles (carbon, nitrogen with atmospheric reservoir) from sedimentary cycles (phosphorus with lithospheric reservoir). Environmental Issues covers current topics like ozone depletion, eutrophication, biomagnification, and e-waste, making it relatable and easier to remember.