Question

question 18
which of these is not a product or reactant of photosynthesis and cellular respiration?
a. energy
b. hydrogen
c. sugar
d. water

Explanation:

1. Recall the equations of photosynthesis and cellular respiration:

• Photosynthesis: \(6CO_2 + 6H_2O+\text{energy (light)}

ightarrow C_6H_{12}O_6 + 6O_2\)

• Cellular respiration: \(C_6H_{12}O_6+6O_2

ightarrow 6CO_2 + 6H_2O+\text{energy (ATP)}\)

1. Analyze each option:

• Option A (energy): Energy is a reactant in photosynthesis (light energy) and a product in cellular respiration (ATP energy).
• Option B (hydrogen): Neither photosynthesis nor cellular respiration has hydrogen (\(H_2\)) as a direct reactant or product. The hydrogen is part of water (\(H_2O\)) or glucose (\(C_6H_{12}O_6\)), not as elemental hydrogen.
• Option C (sugar): Sugar (glucose, \(C_6H_{12}O_6\)) is a product of photosynthesis and a reactant of cellular respiration.
• Option D (water): Water is a reactant in photosynthesis and a product in cellular respiration.

Answer:

B. hydrogen