Waec Model Questions Vol1 2019 Biology Question 48

A desert rodent reduces water loss through three independent adaptations: (i) its urine is highly concentrated, decreasing urinary water loss by 40 % compared with a non‑desert rodent; (ii) a nasal counter‑current heat exchanger lowers respiratory water loss by 30 %; (iii) nocturnal activity reduces metabolic water loss by 25 % relative to diurnal activity. A comparable non‑desert rodent loses 10 mL of water per day in urine, 5 mL by respiration and 8 mL through metabolic processes. In addition, the desert rodent retains 2 mL of metabolic water produced by oxidation of food. Calculate the total daily water loss of the desert rodent after all three adaptations act, and give the result in millilitres to one decimal place.