Question

In the process of photosynthesis, plants use carbon dioxide (CO2), water (H2O), and light energy to produce a sugar (C6H12O6) and oxygen (O2). In the process of aerobic respiration, animals and plants release energy from sugar and oxygen and produce carbon dioxide and water. The chemical equations that describe these reactions look like this:

6CO2 + 6H2O + light --> C6H12O6 + 6O2 C6H12O6 + 6O2 -- > 6CO2 + 6H2O + ATP

How do these equations explain why the total amount of O2 and CO2 remains the same for both reactions? (think about the cycle)
They prove light is essential
They show energy creation
They illustrate conservation of matter
They demonstrate water production

Answer 1

They illustrate conservation of matter.

Explanation: The equations show the same atoms (C, O, H) simply being rearranged between reactants and products: photosynthesis converts CO2 and H2O into sugar and O2, while respiration converts that sugar and O2 back into CO2 and H2O. No atoms are created or destroyed, so the total amounts of O2 and CO2 cycle and remain the same overall.