Questions & Answers

The role of plants in the carbon cycle is
I)Release carbon dioxide to the atmosphere
II)Remove carbon dioxide from the atmosphere
III)Fix carbon dioxide in root nodules
A)I only
B)II only
C)III only
D)I and II only
E)I, II and III

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Hint: The process of continuous formation, breakdown and making use of carbon and its molecules in the atmosphere, biosphere, pedosphere, hydrosphere and lithosphere of the earth is the carbon cycle. It is a kind of biogeochemical or nutrient cycle.

Complete answer:
Carbon has about 49% of the dry weight of organisms. It is estimated that 71% of the global carbon occurs in the dissolved form in oceans. The reservoir of carbon is present in the hydrosphere(oceans), lithosphere (as deposits of fossil fuels) and in the atmosphere (as carbon dioxide). The cyclic pathway of carbon includes the following steps:
Photosynthesis: The carbon takes place and enters the biotic components of the ecosystem through the green plants, photosynthetic bacteria and cyanobacteria in the terrestrial ecosystem and through phytoplankton and hydrophytes in the aquatic ecosystems. These are termed as producers and perform photosynthesis by taking in the atmospheric carbon dioxide and making carbohydrates and oxygen.

Respiration: The carbon that is fixed by the producers now enters the food chain and is consumed by various living organisms. Carbon dioxide is released into the atmosphere by the process of respiration of producers and consumers.
Decomposition: The decomposers help in breakdown of the larger organic compounds into simpler ones and then into inorganic molecules. In this process, a small amount of carbon dioxide is released back to the atmosphere during the enzyme-catalysed breakdown of dead matter by decomposers.
Combustion: The process of Burning of fossil fuels in the automobiles and machinery to produce energy, burning of wood, organic debris also releases carbon dioxide, volcanic eruptions and hot springs also helps to release carbon dioxide into the atmosphere.
So, in carbon cycle two process takes place Release carbon dioxide to the atmosphere and Remove carbon dioxide from the atmosphere

Hence, the correct answer is option (D)

Note: When the content of carbon dioxide levels increases in the atmosphere can lead to climate change in the upcoming future years. This is termed as global warming and is responsible for the unwanted increase of temperature on earth leading to the melting of glaciers that may result in a disaster.