Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

In the water cycle, what is the process called when plants release water vapor into the atmosphere?

1. Evaporation

2. Transpiration

3. Condensation

4. Infiltration

The correct answer is: Transpiration

The process by which plants release water vapor into the atmosphere is known as transpiration. During transpiration, water absorbed by plant roots is transported through plants and eventually evaporates from small openings called stomata found on the leaves. This not only helps in regulating water within the plant but also contributes significantly to the moisture in the atmosphere, playing a crucial role in the water cycle. In contrast, evaporation refers to the process of water changing from a liquid to a vapor state due to heat, which can occur from surfaces like lakes or soil but does not involve plants directly. Condensation is the process where water vapor cools and changes back into liquid water, forming clouds, while infiltration refers to the process of water soaking into the ground and replenishing groundwater sources. These processes are all integral to the water cycle, but transpiration specifically highlights the role of plants in this cyclical movement of water.