ISA Certified Arborist Practice Exam

Photosynthesis is the process by which trees and other green plants absorb carbon dioxide from the atmosphere and, using sunlight as energy, convert it into glucose and oxygen. This process takes place in the chloroplasts of plant cells, primarily in the leaves. During photosynthesis, trees utilize light energy to facilitate the transformation of carbon dioxide and water into sugars, which serve as food for the plant, while releasing oxygen as a byproduct.

Transpiration refers to the process of water movement through a plant and its evaporation from aerial parts, primarily leaves. While it plays a key role in a tree’s water regulation and nutrient uptake, it does not involve the direct absorption and conversion of carbon dioxide.

Respiration is a metabolic process that occurs in both plants and animals, where glucose is broken down to release energy, using oxygen and producing carbon dioxide and water as byproducts. Unlike photosynthesis, this process does not involve the absorption of carbon dioxide for creating glucose; rather, it uses glucose that has already been produced.

Decomposition describes the breakdown of organic materials by microorganisms, ultimately returning nutrients to the soil, but it does not involve the photosynthetic use of carbon dioxide by trees.

Thus, photosynthesis is accurately defined as the process that encapsulates the