Our Environment — Karnataka (SSLC) Class 10 Science Solutions (Free)

Ecosystem: community of living organisms (biotic) and non-living environment (abiotic) interacting together. Food chain: linear transfer of energy (grass → grasshopper → frog → eagle). Food web: interconnected food chains showing multiple feeding relationships. Each organism depends on multiple food sources; removal of one affects entire web.

Biomagnification: increase in concentration of toxic substances (pesticides, heavy metals) as they move up the food chain. E.g., pesticide on grass (0.01 ppm) → grasshopper eats grass (0.1 ppm) → bird eats grasshoppers (1 ppm) → hawk eats birds (10 ppm). Top predators accumulate highest, causing death/deformities.

Ozone layer (15–35 km altitude) absorbs UV-B radiation, protecting life from damage. Depletion caused by CFCs (chlorofluorocarbons) from refrigerators, aerosols breaking down ozone. Consequences: increased UV radiation → skin cancer, cataracts, immune suppression, phytoplankton damage, crop failure. Montreal Protocol (1987) banned CFCs.

Greenhouse effect: CO₂, CH₄, N₂O, water vapor trap infrared radiation, warming Earth. Necessary for life (keeps ~15°C livable), but excess gases from burning fossil fuels increase effect. Result: global temperature rise (now ~1.1°C above pre-industrial) → sea level rise, extreme weather, species extinction, agricultural losses.

Acid rain: precipitation with pH < 5.6, caused by SO₂ and NO₂ from burning coal, petroleum combustion. SO₂ + H₂O → H₂SO₄; NO₂ + H₂O → HNO₃. Effects: (1) Corrodes buildings/statues (Taj Mahal), (2) Acidifies soil/lakes (kills aquatic life), (3) Damages forests, (4) Leaches toxic metals into groundwater.