Question

For the same amount of $C{O}_2$ fixed, a $C_4$ plant, in comparison with a $C_3$ plant, loses only

• A. Half amount of water
• B. Equal amount of water
• C. Double amount of water
• D. None of these.

Answer 1

The correct option is A Half amount of water

Answer is option A i.e. "Half amount of water"
C4​ plant loses half as much as water as a C3​ plant as C4​ plants need not to open their stomata for long to take in carbon dioxide due to high efficiency of the C4​ pathway and this reduces water loss due to transpiration. The water loss per gram of biomass produced with C3 cycle is high (450-950). However, the water loss per gram of biomass produced with C4 cycle is low (250-350)