Announcement
Pollution/Ozone
Assertion (A): The discharge of warm wastewater from thermal power plants into rivers decreases the Biological Oxygen Demand (BOD) of the aquatic ecosystem.
Reason (R): An increase in water temperature drastically reduces the solubility of dissolved oxygen in aquatic environments.
- A A is true, but R is false.
- B Both A and R are true, and R is the correct explanation of A.
- C A is false, but R is true.
- D Both A and R are true, but R is NOT the correct explanation of A.
Explanation: Assertion is false, but Reason is true. Warm wastewater increases the Biological Oxygen Demand (BOD) because warmer water increases the metabolic rates of aquatic organisms, making them demand more oxygen. At the same time, as stated in the true Reason, warmer water holds less dissolved oxygen, creating a double threat to the ecosystem.
Assertion (A): Flooded rice paddies are considered a major anthropogenic source of global methane emissions.
Reason (R): Methanogenic archaea thrive in the anaerobic (oxygen-depleted) conditions created by the prolonged waterlogging of soils.
- A Both A and R are true, but R is NOT the correct explanation of A.
- B A is false, but R is true.
- C A is true, but R is false.
- D Both A and R are true, and R is the correct explanation of A.
Explanation: Both A and R are true, and R explains A. Rice paddies require prolonged flooding, which creates an anaerobic (oxygen-free) soil environment. This is the perfect breeding ground for methanogenic archaea (microbes), which produce massive amounts of methane gas as a metabolic byproduct.
Assertion (A): Ocean iron fertilization has been proposed as a geoengineering technique to mitigate anthropogenic climate change.
Reason (R): Adding iron to the upper ocean stimulates the growth of phytoplankton, which absorb atmospheric carbon dioxide during photosynthesis.
- A Both A and R are true, and R is the correct explanation of A.
- B Both A and R are true, but R is NOT the correct explanation of A.
- C A is true, but R is false.
- D A is false, but R is true.
Explanation: Both A and R are true, and R explains A. Ocean iron fertilization is a geoengineering concept. Iron is a limiting nutrient in many parts of the ocean. By dumping iron dust, we can trigger massive phytoplankton blooms, which draw down atmospheric CO2. When the plankton die, they sink, sequestering the carbon in the deep ocean.
Assertion (A): Catalytic converters installed in automobile exhaust systems use heavy metals like lead and mercury as catalysts to reduce emissions.
Reason (R): Catalytic converters help in reducing the emission of poisonous gases like carbon monoxide and unburnt hydrocarbons into the atmosphere.
- A A is false, but R is true.
- B Both A and R are true, and R is the correct explanation of A.
- C Both A and R are true, but R is NOT the correct explanation of A.
- D A is true, but R is false.
Explanation: Assertion is false, but Reason is true. Catalytic converters use precious metals like Platinum, Palladium, and Rhodium as catalysts, not toxic heavy metals like lead and mercury (in fact, lead poisons the catalyst, which is why unleaded petrol is required). They effectively reduce toxic emissions like CO and unburnt hydrocarbons.
Assertion (A): PM 2.5 is generally considered more detrimental to human health than PM 10.
Reason (R): PM 2.5 particles are small enough to bypass the respiratory system's natural mucous defenses and enter directly into the bloodstream.
- A A is true, but R is false.
- B Both A and R are true, but R is NOT the correct explanation of A.
- C A is false, but R is true.
- D Both A and R are true, and R is the correct explanation of A.
Explanation: Both A and R are true, and R explains A. PM 10 (particles 10 micrometers or less) are mostly trapped by the nose and throat. PM 2.5 is so fine that it penetrates deep into the alveolar regions of the lungs and can cross into the bloodstream, causing severe cardiovascular and respiratory diseases.
Assertion (A): Coral bleaching always indicates the immediate death of the coral organism.
Reason (R): Bleaching occurs when corals expel the symbiotic zooxanthellae algae living in their tissues due to environmental stress.
- A Both A and R are true, and R is the correct explanation of A.
- B A is false, but R is true.
- C A is true, but R is false.
- D Both A and R are true, but R is NOT the correct explanation of A.
Explanation: Assertion is false, but Reason is true. Coral bleaching does not mean immediate death; it means the coral is under stress and has expelled its food-producing algae (which gives it color). If the stress is mild and temperatures drop, the coral can take back the algae and recover. If stress is prolonged, it starves and dies.
Assertion (A): Inhaling carbon monoxide (CO) can be fatal even at relatively low concentrations in enclosed, poorly ventilated spaces.
Reason (R): Carbon monoxide has a 200-times greater affinity for blood hemoglobin than oxygen, forming stable carboxyhemoglobin that starves the body of oxygen.
- A A is true, but R is false.
- B Both A and R are true, and R is the correct explanation of A.
- C A is false, but R is true.
- D Both A and R are true, but R is NOT the correct explanation of A.
Explanation: Both A and R are true, and R explains A. Carbon monoxide is deadly because it vigorously outcompetes oxygen for binding sites on hemoglobin molecules. Once carboxyhemoglobin forms, the blood can no longer transport oxygen to vital organs, leading to asphyxiation.
Assertion (A): Fly ash generated by thermal power plants can be beneficially used in the agricultural sector.
Reason (R): Fly ash improves the water-holding capacity of sandy soils and provides essential macronutrients and micronutrients to plants.
- A Both A and R are true, and R is the correct explanation of A.
- B Both A and R are true, but R is NOT the correct explanation of A.
- C A is true, but R is false.
- D A is false, but R is true.
Explanation: Both A and R are true, and R explains A. While fly ash does contain trace heavy metals (which is a concern in overuse), its controlled application in agriculture is beneficial. It improves the physical texture of soil (like water retention) and is a rich source of macronutrients (K, P, Ca) and micronutrients (Zn, Fe, Cu).
Assertion (A): The excessive extraction of groundwater in the Ganga-Brahmaputra basin has triggered widespread geogenic arsenic contamination.
Reason (R): Over-extraction lowers the water table, exposing underground arsenic-bearing pyrites to atmospheric oxygen, which makes the arsenic soluble in water.
- A Both A and R are true, and R is the correct explanation of A.
- B Both A and R are true, but R is NOT the correct explanation of A.
- C A is true, but R is false.
- D A is false, but R is true.
Explanation: Both A and R are true, and R explains A. Arsenic in the Ganga-Brahmaputra basin is naturally occurring (geogenic) in the bedrock. However, anthropogenic over-extraction of groundwater lowers the water table. This allows oxygen to enter the previously saturated aquifers, oxidizing the arsenic-rich pyrites and leaching soluble arsenic into the drinking water.
Assertion (A): Bioremediation using agents like 'Oilzapper' is an ecologically sound way to clean up ocean crude oil spills.
Reason (R): Oilzapper is a genetically engineered consortium of bacteria that completely degrades hazardous crude oil compounds into harmless CO2 and water.
- A Both A and R are true, but R is NOT the correct explanation of A.
- B A is true, but R is false.
- C Both A and R are true, and R is the correct explanation of A.
- D A is false, but R is true.
Explanation: Both A and R are true, and R explains A. TERI developed 'Oilzapper' as an eco-friendly bioremediation solution. It consists of a mixture of five bacterial strains that feed on hydrocarbon compounds present in crude oil, breaking them down metabolically into environmentally safe end-products: carbon dioxide and water.
Click to toggle correct answers and explanations for all questions.