Free ISA Tree Biology and Physiology Questions and Answers

Question 1

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

Accepted Answer

Transporting sugars produced during photosynthesis from the leaves to other parts of the tree.

Answer

The phloem is a critical component of a tree's vascular system responsible for transporting the sugars (produced via photosynthesis in the leaves) to areas of growth and storage, such as the roots, fruits, and meristems. Xylem transports water, heartwood provides support, and the bark is the protective layer.

Question 2

An arborist observes a tree with a tall, dominant central leader and suppressed lateral branch growth. This growth pattern is a classic example of:

Accepted Answer

Apical dominance

Answer

Apical dominance is the phenomenon where the central, terminal bud (apical bud) produces hormones, primarily auxin, that inhibit the growth of the lateral buds below it. This results in the tree prioritizing vertical growth over lateral branching, leading to a strong central leader.

Question 3

The process by which a tree releases water vapor into the atmosphere through small pores (stomata) in its leaves is known as:

Accepted Answer

Transpiration

Answer

Transpiration is the process of water movement through a tree and its evaporation from aerial parts, such as leaves. This process is vital for cooling the tree, moving water and nutrients from the roots, and enabling the uptake of carbon dioxide for photosynthesis.

Question 4

According to the CODIT model (Compartmentalization of Decay in Trees), which 'wall' is considered the strongest and is formed by the cambium after an injury occurs, separating new wood from the damaged tissue?

Accepted Answer

Wall 4

Answer

Wall 4, also known as the barrier zone, is the strongest of the four walls in the CODIT model. It is new wood tissue produced by the cambium after the injury, forming a protective barrier that prevents the spread of decay into the wood that grows after the wound occurs.

Question 5

A client is concerned about a large, mature oak tree in their yard after a recent period of soil compaction from construction equipment. Why is oxygen in the soil crucial for the health of the tree's root system?

Accepted Answer

Oxygen is necessary for the process of root respiration, which releases energy for growth and nutrient uptake.

Answer

Tree roots, like other living cells, must perform respiration to break down sugars and release energy for vital functions, including growth and the active uptake of mineral nutrients. This process requires oxygen. Soil compaction reduces pore space, limiting oxygen availability and impairing root health and function.

(ISA) ISA Certified Arborist Practice Test

(ISA) ISA Certified Arborist Practice Test

Free ISA Tree Biology and Physiology Questions and Answers