Ecology and Environment: Ecosystems, Biodiversity, Conservation and Environmental Issues
Expect numerical energy-flow questions, pyramid interpretation, and matching of Indian conservation examples and IUCN categories. Definitions must be exact - biomagnification and bioaccumulation are routinely swapped.
Core rules
- Ecosystem components: producers, consumers (primary to tertiary) and decomposers, acting on abiotic factors.
- Energy flow is unidirectional; Lindeman's 10% law; gross primary productivity minus respiration equals net primary productivity. Pyramids of number, biomass and energy - the pyramid of energy is always upright.
- Nutrient cycles are gaseous (carbon, nitrogen) or sedimentary (phosphorus, sulphur).
- Succession: hydrarch and xerarch; pioneer community → seral stages → climax community.
- Biodiversity hotspots of India: Western Ghats–Sri Lanka, Himalaya, Indo-Burma and Sundaland (Nicobar Islands).
- IUCN Red List categories: Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern, Data Deficient, Not Evaluated.
- In-situ conservation: national parks, wildlife sanctuaries, biosphere reserves, sacred groves. Ex-situ: botanical gardens, seed banks, cryopreservation, tissue culture.
- Pollution issues: greenhouse gases (CO₂, CH₄, N₂O, CFCs), ozone depletion by CFCs and the Montreal Protocol, eutrophication, biomagnification of organochlorine pesticides.
Worked example
Grass stores 20,000 kJ. At 10% transfer, primary consumers receive 2,000 kJ, secondary consumers 200 kJ and tertiary consumers 20 kJ. A non-degradable pollutant reaches its highest tissue concentration in the tertiary consumer - this is biomagnification, the increase along the chain, not bioaccumulation within one organism.
Traps that cost marks
Drawing an inverted pyramid of energy; confusing a biodiversity hotspot with any biodiversity-rich country; placing a botanical garden under in-situ conservation; stating the 10% law as a law of energy conservation rather than of transfer.