Gce Model Questions Vol1 2020 Biology Question 46

Two desert plants use different photosynthetic adaptations. Plant A employs CAM photosynthesis, opening its stomata at night for \(8\ \text{h}\). Plant B uses the C\(_4\) pathway, opening its stomata during the day for \(6\ \text{h}\). At a reference temperature of \(25^{\circ}\text{C}\) the base transpiration rates are \(0.5\ \text{g h}^{-1}\) for Plant A and \(1.2\ \text{g h}^{-1}\) for Plant B. The actual transpiration rate changes with temperature: for each degree above \(25^{\circ}\text{C}\) it increases by \(5\%\) and for each degree below \(25^{\circ}\text{C}\) it decreases by \(3\%\). Night temperature is \(20^{\circ}\text{C}\) and day temperature is \(35^{\circ}\text{C}\). Calculate the total water loss of each plant in one day and state which adaptation conserves water better.