Certified Arborist Practice Test

Stomata are small pores found on the surface of leaves and stems that play a crucial role in gas exchange for plants. They are primarily responsible for the intake of carbon dioxide, which is essential for photosynthesis, and the release of oxygen as a byproduct of this process. Additionally, stomata facilitate the transpiration process, where water vapor is released from the plant into the atmosphere. This function helps regulate moisture levels within the plant and contributes to nutrient transport through the plant's vascular system.

The other options refer to different parts of a plant. Leaf veins are vascular tissues that transport water and nutrients, while the roots anchor the plant and absorb water and minerals from the soil. The outer layer of trees, typically known as bark, serves to protect the tree and does not contribute to gas exchange. Understanding the function of stomata helps illustrate their vital role in the overall health and efficiency of plant processes.