Study the diagram given below and answer the questions that follow: . Why is oil placed over water?

Oil is placed over water to prevent evaporation of water from the test tube. Transpiration is the process by which plants lose water as vapours through the aerial parts. To prevent evaporation of water from the surface inside the tube, oil is placed. In bright sunlight the extent of water decreases quickly.

Study the diagram given below and answer the question that follows: . What do we observe with regard to the level of water when this set-up is placed in bright sunlight.

Water is necessary for plants but only a small amount of water taken up by the roots is used for growth and metabolism. The remaining 97–99.5% is lost by transpiration and guttation. When this set-up is placed in bright sunlight there is decrease in water level as the rate of transpiration increases. In bright sunlight the level of water decreases rapidly.

Study the diagram given below and answer the question that follow: . What do we observe with regard to the level of water when this set-up is placed in humid conditions.

As the humidity of the air surrounding the plant rises the transpiration rate falls. It is easier for water to evaporate into dryer air than into more saturated air. When this set-up is placed in humid conditions there will be a negligible change in water level as the rate of transpiration is minimum.

Study the diagram given below and answer the questions that follow: . What do we observe with regard to the level of water when this set-up is placed in windy day.

Wind will move the air around, with the result that the more saturated air close to the leaf is replaced by drier air. When this set-up is placed on windy days there will be a decrease in water level due to more transpiration as the rate of transpiration increases with wind velocity.

Study the diagram given below and answer the question that followss: . Mention any three adaptations found in plants to overcome the transpiration process.

The three adaptations by which plants tend to scale back transpiration are: 1. Narrower leaves reduce the surface area, in some cases, they are modified in spines. 2. Thick layer of the cuticle reduces the rate of transpiration. 3. The reduced number of stomata on the upper layer of leaves also reduces the rate of transpiration.