Which of the following best describes the relationship between cellular respiration and photosynthesis?

• A. Cellular respiration is essentially the reverse of photosynthesis, with reactants and products swapped.
• B. Cellular respiration produces glucose, while photosynthesis breaks it down.
• C. Both processes require oxygen as a reactant.
• D. Cellular respiration and photosynthesis are unrelated processes.

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the processes of photosynthesis and cellular respiration. Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose. Cellular respiration is the process by which organisms break down glucose to release energy in the form of ATP.
2. Step 2: Compare the chemical equations for both processes. Photosynthesis can be represented as: ${6\mathrm{CO}2}_{}+{6H2O}_{}\to {C6H\mathrm{12}O6}_{}+{6O2}_{}$. Cellular respiration can be represented as: ${C6H\mathrm{12}O6}_{}+{6O2}_{}\to {6\mathrm{CO}2}_{}+{6H2O}_{}+\mathrm{ATP}$.
3. Step 3: Observe that the reactants of photosynthesis (carbon dioxide and water) are the products of cellular respiration, and the products of photosynthesis (glucose and oxygen) are the reactants of cellular respiration. This demonstrates that the two processes are essentially reverse reactions.
4. Step 4: Clarify the role of oxygen. Photosynthesis produces oxygen as a byproduct, while cellular respiration uses oxygen as a reactant to break down glucose. Therefore, the statement 'Both processes require oxygen as a reactant' is incorrect.
5. Step 5: Conclude that the best description of the relationship between cellular respiration and photosynthesis is that cellular respiration is essentially the reverse of photosynthesis, with reactants and products swapped.