Question

recall the summary reactions for cellular respiration and photosynthesis, which give the \what gets used up\ reactants on the left side and \what comes out at the end\ products on the right side:
respiration: ( c_6h_{12}o_6 + 6o_2 \to 6co_2 + 6h_2o + atp )
photosynthesis: ( 6co_2 + 6h_2o + \text{light energy} \to c_6h_{12}o_6 + 6o_2 )
in what sense are cellular respiration and photosynthesis opposites?
○ in each process, the etc and atp synthase run in the opposite direction.
○ the reactants and products of photosynthesis (( co_2 + h_2o + \text{energy} ) and ( \text{glucose} + o_2 )) are the products and reactants of cellular respiration.
○ cellular respiration produces glucose, while photosynthesis consumes glucose.
consider the overall equations for each process again. in terms of reactants and products, the two processes appear to be the reverse of each other. which two statements explain why they are not just the reverse of one another? select the two best answers.
□ most of the key molecules, machines, and specific chemical reactions are different between the two processes.
□ one occurs only during the day; one occurs only at night.
□ overall, photosynthesis is about transforming light energy to chemical energy. overall, cellular respiration is a transfer of chemical energy from glucose to atp.
□ photosynthesis only occurs in plants, while cellular respiration only occurs in animals.

Explanation:

• For the first question:
• Analyze each option. In cellular respiration, glucose and oxygen are reactants, and carbon dioxide and water are products. In photosynthesis, carbon dioxide and water (along with light energy) are reactants, and glucose and oxygen are products. So, the reactants and products of photosynthesis are the products and reactants of cellular respiration.
• For the second question:
• Option 1: The key molecules (e.g., different enzymes in electron - transport chain (ETC) and ATP synthase in different contexts), machines (different organelles play different roles in a more detailed sense, like chloroplasts in photosynthesis and mitochondria in respiration), and specific chemical reactions (e.g., light - dependent reactions in photosynthesis vs. glycolysis, Krebs cycle in respiration) are different.
• Option 3: Photosynthesis is about converting light energy to chemical energy (stored in glucose), while cellular respiration is about transferring chemical energy from glucose to ATP (a more immediately usable form of energy for the cell).

Answer:

• First question: The reactants and products of photosynthesis ($CO_2 + H_2O+$ energy and glucose $+O_2$) are the products and reactants of cellular respiration.
• Second question: Most of the key molecules, machines, and specific chemical reactions are different between the two processes; Overall, photosynthesis is about transforming light energy to chemical energy. Overall, cellular respiration is a transfer of chemical energy from glucose to ATP.