Gce Model Questions Vol1 2023 Biology Question 27

Two desert shrubs, Species A and Species B, employ different leaf adaptations to minimise water loss. Species A has a leaf area of \(150\ \text{cm}^2\) and a stomatal density of \(250\ \text{stomata\,mm}^{-2}\). Each stomata transpires water at a rate of \(0.02\ \text{mmol\,H}_2\text{O\,h}^{-1}\). Species B has a leaf area of \(120\ \text{cm}^2\) and a stomatal density of \(180\ \text{stomata\,mm}^{-2}\), with each stomata transpiring at \(0.025\ \text{mmol\,H}_2\text{O\,h}^{-1}\). Both species produce \(0.9\ \text{g}\) dry biomass per day. Calculate the water‑use efficiency (WUE) for each species, defined as grams dry biomass produced per mole of water lost, and state which species shows the more efficient drought adaptation.