Question

A friend of yours has a terrarium on her windowsill containing various houseplants. She wonders why the glass is often fogged with water droplets. What would you tell her is the cause of the droplets?

A. adhesion
B. photosynthesis
C. pressure flow
D. root pressure
E. transpiration

Answer 1

Transpiration is the cause of the water droplets on the terrarium glass, as plants release water vapor, which then condenses. This process involves the movement of water through the plant due to cohesion and adhesion of water molecules.

Step-by-step explanation:

The cause of the water droplets fogging the glass of the terrarium is transpiration. This is a process where plants release water vapor through leaf pores called stomata. In the closed environment of a terrarium, this water vapor then condenses on the cool glass surface, forming droplets. During transpiration, water from the roots is pulled up due to negative pressure and as water evaporates from the leaves into the air inside the terrarium, it increases the humidity. Eventually, when the water vapor comes in contact with the cooler glass, it changes back into liquid water, creating the fogged appearance. This process is essential for the transport of water and nutrients from the roots to the leaves of the plant.

Tension created during transpiration helps the ascent of sap due to cohesion and adhesion of water molecules. Cohesion keeps the water molecules bonded together, while adhesion helps them cling to the plant tissues, which aids in the movement of water against gravity from the roots up through the plant.