Neco Model Questions Vol1 2025 Biology Question 13

Desert plants use structural and physiological adaptations to minimise water loss.\n\nA cactus employs CAM photosynthesis, opening its stomata only at night for 8 h at a transpiration rate of \(0.2\ \text{g h}^{-1}\). During the day its stomata are closed, so water loss is negligible.\n\nA typical non‑CAM desert shrub keeps its stomata open during the day for 12 h at \(0.8\ \text{g h}^{-1}\) and at night for 12 h at \(0.3\ \text{g h}^{-1}\).\n\nCalculate the total water loss (in grams) for each plant over a 24‑hour period and the percentage reduction in water loss achieved by the cactus. Which type of adaptation (structural - spines reducing surface area, or physiological - CAM) contributes most to this reduction? Provide a brief justification.