A student measured the rate of water uptake of a leafy shoot using a potometer under four sets of conditions. The results were: still air at 20 C = 1.0 cm3 per hour; air moved by a fan at 20 C = 2.4 cm3 per hour; still humid air at 20 C = 0.4 cm3 per hour; still air at 30 C = 1.8 cm3 per hour.