Water loss ratio in photosynthesis

Steps:

• Photosynthesis equation: 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂, requiring 6 CO₂ per glucose.
• Plants lose 400 H₂O per CO₂ gained through open stomata.
• Calculate total loss: 6 CO₂ × 400 H₂O/CO₂ = 2400 H₂O.
• This accounts for CO₂ fixation during glucose synthesis.

Why D is correct:

• Balanced photosynthesis equation mandates 6 CO₂ molecules for one glucose, yielding 6 × 400 = 2400 H₂O lost.

Why the others are wrong:

• A: Assumes only 2 CO₂ (800 H₂O), ignoring full equation.
• B: Assumes 3 CO₂ (1200 H₂O), undercounting CO₂ needs.
• C: Assumes 5 CO₂ (2000 H₂O), still short of 6 required.

Final answer: D