Question

Identify what keeps this entire cycle of photosynthesis and aerobic respiration going indefinitely and why. (3) Explain how increasing amounts of atmospheric carbon dioxide and deforestation have affected this cycle and climate.

Answer 1

Photosynthesis and cellular respiration are both reverse of each other. The substrates of one process are the products of the other process and vice versa.

Photosynthesis is the process of formation of glucose and oxygen with the help of atmospheric carbon dioxide and water absorbed by plants roots from the soil. It is an anabolic process. The overall Delta G for this process is positive and the process is nonspontaneous. It is an endergonic process. It takes place in chloroplast of plants and some of the bacteria. This process consumes ATP.

Respiration is the process of breakdown of glucose into carbon dioxide and water in the presence of oxygen. It is a catabolic process. The overall Delta G for the process is negative and it is spontaneous. It is an exergonic process. It takes place in mitochondria of all the eukaryotes and cell membrane and cytosol of all the prokaryotes. This process results in the formation of ATP which is used by the cell to perform its metabolic activities.

So the relationship between these two processes which keeps the entire cycle of photosynthesis and aerobic respiration to go in definitely is that aerobic respiration leads to the production of carbon dioxide and water. Carbon dioxide is absorbed by the plants through stomata and water is absorbed through roots and both are utilised for the fixation of glucose. Plant themselves use glucose for aerobic respiration and other organisms which are dependent upon plants are consuming glucose through plants. These organisms also breakdown glucose obtained from plants by aerobic respiration. And when the organism release carbon dioxide and water into the atmosphere after aerobic respiration, it is again absorbed by the plants and the whole process repeats.

Increasing atmospheric carbon dioxide concentration and deforestation and related to each other. More the number of plants are there in the environment, higher will be the rate of photosynthesis and more amount of carbon dioxide will be fixed into glucose and this will help in keeping the atmospheric carbon dioxide concentration at lower levels. But deforestation has led to decline in the number of plants and therefore the rate of photosynthesis has also decrease. Because of this, the concentration of carbon dioxide in the atmosphere has increased which has led to an increase in the global temperature and has affected climate adversely.

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