The law of conservation of mass states that mass cannot be created or destroyed in a closed system. It applies directly to photosynthesis and respiration, as these processes involve the rearrangement of atoms, not their disappearance or creation.

Here's how it works in each process:

Photosynthesis:

* Equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

* Explanation: Six molecules of carbon dioxide (CO₂) and six molecules of water (H₂O) are used as reactants. These molecules are rearranged to form one molecule of glucose (C₆H₁₂O₆) and six molecules of oxygen (O₂). The total number of atoms on each side of the equation is the same.

* Conservation of Mass: The total mass of the reactants (CO₂ and H₂O) is equal to the total mass of the products (C₆H₁₂O₆ and O₂). No mass is lost or gained during the process.

Respiration:

* Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

* Explanation: Glucose (C₆H₁₂O₆) reacts with six molecules of oxygen (O₂) to produce six molecules of carbon dioxide (CO₂) and six molecules of water (H₂O). Again, the number of atoms on each side of the equation is balanced.

* Conservation of Mass: The total mass of glucose and oxygen is equal to the total mass of carbon dioxide and water. No mass is lost or gained during the process.

In essence, photosynthesis and respiration are essentially reverse reactions. Photosynthesis "stores" chemical energy by converting light energy into the chemical bonds of glucose. Respiration "releases" that energy by breaking those bonds and using the energy to power cellular activities.

The law of conservation of mass is a fundamental principle that underlies these essential biological processes, ensuring that matter is neither created nor destroyed, only rearranged.