Question

In tomato plants, drops of water are seen along leaf margins in the morning because of

• A. guttation
• B. transpiration
• C. imbibition
• D. plasmolysis

Answer 1

The correct option is A guttation

Due to high humidity, cool air and warm soil, water can move upto the leaves due to root pressure at night. Water absorbed by the roots enters a plant's stem and travels up to its leaves. Some of the water here is used in photosynthesis, the remaining escapes through the stomata through evaporation. This process of loss of water in the form of vapours from the aerial parts of the plant is called transpiration.
Transpiration cannot remove water from the leaves at night, as it does during the day. This is because the stomata is closed during night time. This results in the exudation of liquid through special openings present on the the leaf margins called hydathodes. The process of exudation of liquid (xylem sap) from the margins of leaves of vascular plants is known as guttation.
Imbibition is a special type of diffusion in which water molecules are absorbed by solids causing an increase in volume.
When the cell is placed in a solution that is hypertonic (has more solutes) to the protoplasm, water moves out of the cell and the cell membrane of a plant cell shrinks away from its cell wall. This process is known as plasmolysis. There is no water loss associated with imbibition and plasmolysis.