Answer: Natural process where certain atmospheric gases (CO 2 , water vapour, CH 4 ) trap outgoing infrared radiation from Earth's surface, warming the planet; essential for life but enhanced by human activities causes global warming.
- A Plants actively trapping carbon dioxide molecules within their chloroplasts mainly for use during the process of photosynthesis under usual circumstances according to most researchers in the majority of cases studied
- B Natural process where certain atmospheric gases (CO<sub>2</sub>, water vapour, CH<sub>4</sub>) trap outgoing infrared radiation from Earth's surface, warming the planet; essential for life but enhanced by human activities causes global warming
- C The straightforward physical trapping of ordinary visible sunlight by glass panels installed inside a typical residential garden greenhouse structure used for growing plants as widely reported in standard practice under most conditions encountered
- D The highly selective filtering effect that the stratospheric ozone layer has mainly on incoming ultraviolet-B solar radiation wavelengths specifically as frequently observed in practice in many documented cases according to conventional understanding
Correct answer: B. Natural process where certain atmospheric gases (CO<sub>2</sub>, water vapour, CH<sub>4</sub>) trap outgoing infrared radiation from Earth's surface, warming the planet; essential for life but enhanced by human activities causes global warming
Explanation: Natural greenhouse effect: solar radiation (shortwave) passes through atmosphere to Earth's surface; surface re-emits longwave (infrared) radiation; greenhouse gases absorb and re-emit this, warming Earth. Without it: Earth temperature would be -18 degrees C (current average: +15 degrees C). Enhanced greenhouse effect (human CO<sub>2</sub>) is causing additional warming.
Sunlight passes through the atmosphere and warms the surface; the surface re-radiates this energy as infrared heat, which greenhouse gases (CO₂, CH₄, water vapour) absorb and trap - a naturally beneficial process that intensifies into global warming as gas concentrations rise from human activity.
Concept context
Pollution, global warming, ozone depletion, deforestation, and sustainability. Important for NEET and general awareness.