Biological Oxygen Demand (BOD) is a standard criterion for:

Question

UnlockIAS · Accepted Answer

Correct — B, Pollution assay in aquatic ecosystems. BOD is the amount of dissolved oxygen that aerobic microorganisms consume to break down the organic matter in a water sample over a set period (typically 5 days at 20°C). The more organic pollution (sewage, effluent) a water body carries, the more oxygen the microbes use up — so a HIGH BOD indicates heavy organic pollution. BOD is therefore a standard yardstick for organic pollution / water quality in aquatic ecosystems.

Why the other options are wrong — (a) Oxygen in blood is measured by blood-gas analysis or pulse oximetry (as SpO₂/PaO₂), which has nothing to do with BOD.  (c) Atmospheric oxygen at altitude is a matter of air pressure, not BOD; BOD is a water-quality parameter.  (d) BOD applies to organic pollution in water, not to oxygen in terrestrial/forest ecosystems.

Concept: BOD measures how much dissolved oxygen aerobic microbes need to decompose the biodegradable organic matter in water. It is an indirect but standard indicator of organic pollution: clean water has a low BOD, while sewage- or effluent-laden water has a high BOD because more organics feed more oxygen-hungry microbes.

State PCS 2023 Q110 — Environment & Ecology PYQ with Answer

State PCS 2023 Q110 — Environment & Ecology PYQ with Answer