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 statement which is NOT correct for carbon cycle.

The environmental reservoir regulate the amount of CO₂ in the ocean.

The correct answer is Option (4) – The environmental reservoir regulate the amount of CO2 in the ocean

The reservoir for gaseous type of nutrient cycle (e.g., nitrogen, carbon cycle) exists in the atmosphere and for the sedimentary cycle (e.g., sulphur and phosphorus cycle), the reservoir is located in Earth’s crust.

When you study the composition of living organisms, carbon constitutes 49 per cent of dry weight of organisms and is next only to water. If we look at the total quantity of global carbon, we find that 71 per cent carbon is found dissolved in oceans. This oceanic reservoir regulates the amount of carbon dioxide in the atmosphere. The environmental reservoir does not regulate the amount of CO₂ in the ocean. The ocean is the largest reservoir of carbon on Earth, and it can absorb and release CO₂ from the atmosphere.

The other statements are all correct:

• There is respiratory release of carbon in the atmosphere. Respiration is the process by which organisms break down glucose to produce energy, and it releases carbon dioxide into the atmosphere.
• The gaseous reservoir of carbon is atmosphere. The atmosphere is the main reservoir of gaseous carbon dioxide.
• Carbon dioxide is a major constituent of greenhouse gases. Greenhouse gases are gases that trap heat in the atmosphere, and carbon dioxide is one of the most important greenhouse gases.