Waec Model Questions Vol1 2023 Biology Question 13

A desert rodent employs three independent water‑conserving mechanisms: (i) its urine is concentrated to an osmolality of 3000 mOsm kg⁻¹, whereas a typical mammal excretes urine at 900 mOsm kg⁻¹; urine accounts for 40 % of its total daily water loss. (ii) a nasal counter‑current heat exchanger recovers 60 % of the evaporative water loss from breathing; breathing contributes 30 % of the total water loss after the urine adaptation has taken effect. (iii) the rodent is nocturnal, reducing its exposure temperature by 15 °C compared with a diurnal lifestyle; each 1 °C drop in ambient temperature lowers total water loss by 0.1 mL day⁻¹. If the basal water loss of a comparable diurnal mammal at 30 °C is 5 mL day⁻¹, calculate the rodent's total water loss per day after all three adaptations act, assuming independence of the mechanisms. Give your answer to two decimal places.