Certified Arborist Test Tree Biology and Physiology Questions and Answers

Question 1

Which of the following describes the primary function of phloem tissue in a tree?

Accepted Answer

Transporting sugars from the leaves to other parts of the tree.

Answer

The phloem is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis, known as photosynthates, in particular the sugar sucrose, to parts of the plant where needed. This transport process is called translocation.

Question 2

A mature oak tree in a parking lot island is showing signs of stress, including leaf scorch and premature fall coloration. The soil is heavily compacted. Which physiological process is most directly inhibited by the soil compaction?

Accepted Answer

Respiration in the roots

Answer

Soil compaction reduces pore space, which limits the availability of oxygen. Tree roots require oxygen to perform respiration, the process of converting sugars into energy for growth and nutrient uptake. Without adequate oxygen, root function declines, leading to poor water and nutrient absorption and overall tree stress.

Question 3

The plant hormone primarily responsible for promoting cell division and found in high concentrations in root tips is:

Accepted Answer

Cytokinin

Answer

Cytokinins are a class of plant hormones that promote cell division (cytokinesis) in plant roots and shoots. They are involved in cell growth and differentiation, affecting apical dominance, axillary bud growth, and leaf senescence.

Question 4

According to the CODIT model (Compartmentalization of Decay in Trees), which 'wall' is the strongest and most effective at stopping the spread of decay?

Accepted Answer

Wall 4, the barrier zone formed by new growth after the injury.

Answer

CODIT describes four walls that trees form to resist the spread of decay. Wall 4 is the new protective wall formed by the cambium after the tree is wounded. It is considered the strongest barrier because it separates the tissue present at the time of wounding from the new tissue that forms subsequently.

Question 5

Transpiration is the process of water movement through a tree and its evaporation from aerial parts. Which of the following environmental conditions would most likely DECREASE the rate of transpiration?

Accepted Answer

High relative humidity

Answer

Transpiration is driven by the water potential gradient between the moist interior of the leaf and the drier air outside. High relative humidity means the air is already saturated with water vapor, which reduces the steepness of this gradient and therefore slows the rate of evaporation from the leaves.

Certified Arborist Test Practice Test

Certified Arborist Test Practice Test

Certified Arborist Test Tree Biology and Physiology Questions and Answers