Fossil fuel also represent a reservoir of carbon. Carbon cycling occurs through atmosphere, ocean and through living and dead organisms. According to one estimate, 4 × 1013 kg of carbon is fixed annually in the biosphere through photosynthesis. A considerable amount of carbon returns to the atmosphere as CO2 through respiratory activities of the producers and consumers. Decomposers also contribute substantially to CO2 pool by their processing of waste materials and dead organic matter of land or oceans. Some amount of the fixed carbon is lost to sediments and removed from circulation. Burning of wood, forest fire and combustion of organic matter, fossil fuel, volcanic activity are additional sources for releasing CO2 in the atmosphere.
Identify the human activity which has major influence on the carbon cycle.
A. Photosynthesis
B. Deforestation
C. Wheat crop plantation
D. Burning of fossil fuels
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → B and D only
A. Photosynthesis — Incorrect. Photosynthesis is a natural process of plants, not a human activity.
B. Deforestation — Correct. Fewer trees take up less CO2, and burning or rotting wood releases it.
C. Wheat crop plantation — Incorrect. Growing crops does not have a major effect on the carbon cycle.
D. Burning of fossil fuels — Correct. It releases carbon locked up for millions of years as CO2.
Note: This passage is taken from NCERT as it is.