Question

The diagram represents a process in plants.
The setup was placed in the bright sunlight. Answer the following question.
What happens to the level of water when this setup is placed in:
$1$. Humid conditions?
$2$. Windy conditions?

Answer 1

The diagram represents the measurement of rate of transpiration in plants. A thin film of oil is applied over the water in the vessel to prevent its evaporation. As the plant transpires, water will evaporate from the leaves and this will create a suction pull that will cause the plant roots to absorb water from the vessel. This will cause decrease in weight of the apparatus.

When the setup is placed:

1. In humid conditions, the air is saturated with water vapour. This causes a decline in the rate of transpiration. Since the transpiration will be less, the water level of the vessel will not fall.

2. In windy conditions, transpiration is more as moving air causes the water to evaporate from the surface of the leaves and this in turn causes more water to get absorbed by the roots of the plant. Thus, water level in the vessel will fall.