Question Video: Representing the Equations of Photosynthesis, Combustion, and Respiration Reactions Chemistry

Match the equations to the processes. A: CH₄ + 2O₂ ⟶ CO₂ + 2H₂O. B: 6CO₂ + 6H₂O ⟶ C₆H₁₂O₆ + 6O₂. C: C₆H₁₂O₆ + 6O₂ ⟶ 6CO₂ + 6H₂O. 1. Photosynthesis 2. Combustion 3. Respiration. [A] A : 3, B : 2, C : 1 [B] A : 2, B : 3, C : 1 [C] A : 1, B : 3, C : 2 [D] A : 1, B : 2, C : 3 [E] A : 2, B : 1, C : 3


Video Transcript

Match the equations to the processes. A: CH4 plus 2O2 giving CO2 plus 2H2O, B: 6CO2 plus 6H2O giving C6H12O6 plus 6O2, C: C6H12O6 plus 6O2 giving 6CO2 plus 6H2O. And the possible processes are 1: photosynthesis, 2: combustion, 3: respiration. The answer options are (A) A:3, B:2, C:1; (B) A:2, B:3, C:1; (C) A:1, B:3, C:2; (D) A:1, B:2, C:3 ;or (E) A:2, B:1, C:3.

In the four main processes of the carbon cycle, photosynthesis is the only one which removes carbon dioxide from the atmosphere. In producers such as green plants, phytoplankton, some bacteria, and algae, carbon dioxide and water react together in the presence of energy from sunlight to produce glucose and oxygen. Equation B and process 1 belong together. The other three processes produce carbon dioxide by very similar equations. The general equation for these three processes is carbon compound plus oxygen forming carbon dioxide and water. In respiration, glucose reacts with oxygen to produce carbon dioxide, water, and ATP. And this happens in every living cell, both plant and animal. ATP is the molecule which transfers or delivers energy to carry out cellular processes. We can see that equation C and the process respiration belong together.

Combustion is the process of burning of fuel in the presence of oxygen to produce carbon dioxide, water, and energy. The equation in purple is a specific example of a fuel burning and oxygen. Here, the fuel is methane gas, CH4. This equation is the same as equation A and matches or belongs to process 2, combustion. So, equation A belongs to process 2; equation B, process 1; and equation C, process 3. The last process in the carbon cycle, decomposition, also produces carbon dioxide, water, and energy, as well as inorganic nutrients which go back into the soil, for example, nitrates and phosphates.

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