Consider the following statements:
1. Energy flows through the ecosystem in the form of carbon-carbon bonds
2. All carbon in biological systems ultimately comes from autotrophic plants
Which among the above statements is / are correct?

Answer: [C] Both 1 & 2

On land and in the water, plants take up carbon dioxide and convert it in to carbohydrates through photosynthesis. This carbon in the plants now has three possible fates, [t can be liberated to the atmosphere by the plant through respiration; it can be eaten by an animal, or it can be present in the plant when the plant dies. Animals obtain all their carbon through their food, and, thus, all carbon in biological systems ultimately comes from plants (autotrophs).

In the animal, the carbon also has the same three possible fates. Carbon from plants or animals that is released to the atmosphere through respiration will either be taken up by a plant in photosynthesis or dissolved in the oceans. When an animal or a plant dies, two things can happen to the carbon in it. It can either be respired by decomposers, or it can be buried intact and ultimately form coal, oil, or natural gas. The fossil fuels can be mined and burned in the future; releasing carbon dioxide to the atmosphere. Otherwise, the carbon in limestone or other sediments can only be released to the atmosphere when they are sub ducted and brought to volcanoes, or when they are pushed to the surface and slowly weathered away. Humans have a great impact on the carbon cycle because when we burn fossil fuels we release excess carbon dioxide into the atmosphere. This means that more carbon dioxide goes into the oceans, and more is present in the atmosphere. The latter condition causes global warming, because the carbon dioxide in the atmosphere allows more energy to reach the Earth from the sun than it allows to escape from the Earth into space. Figure 3.6 illustrates the above processes in the carbon cycle.

This question is a part of GKToday's Integrated IAS General Studies Module