Certified Arborist Practice Exam

The loss of water vapor from the leaves is called:

1. Stomata

2. Transpiration

3. Xylem

4. Phloem

The correct answer is: Transpiration

The process of losing water vapor from the leaves is known as transpiration. This process plays a crucial role in the water cycle and helps plants regulate their temperature and maintain nutrient flow. Transpiration occurs primarily through small openings in the leaves called stomata, where water vapor exits while carbon dioxide enters for photosynthesis. The other terms mentioned relate to different components of plant physiology. Stomata are the structures that facilitate the gas exchange process, but they do not define the process of water loss itself. Xylem is the tissue responsible for transporting water and nutrients from the roots to the rest of the plant, while phloem carries the products of photosynthesis. Understanding these functions helps clarify the essential role of transpiration in plant health and ecosystem dynamics.