ISA Certified Arborist Practice Exam

ISA Certified Arborist Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

Tree Biology and Physiology

• Which layer of a tree is primarily responsible for water transport?
• Phloem
• Cambium
• Xylem
• Bark

Xylem transports water and minerals from the roots to the leaves.

• Which plant hormone is primarily responsible for promoting cell

elongation?

• Ethylene
• Auxin
• Gibberellin 1 / 4

• Cytokinin

Auxin promotes cell elongation, especially in stems and young shoots.

• Which part of the tree produces new xylem and phloem each year?
• Bark
• Cambium
• Pith
• Cortex

The cambium is a layer of dividing cells that generates xylem inward and phloem outward.

• What is the primary function of phloem?
• Water absorption
• Nutrient storage
• Transport of sugars
• Structural support

Phloem transports sugars produced in leaves to other parts of the plant.

• What type of root system is characterized by a single dominant

taproot?

• Taproot system
• Fibrous root system
• Adventitious roots
• Buttress roots 2 / 4

Taproots have one main root that grows downward, typical of many trees.Tree Identification

• Which leaf arrangement is opposite?
• Maple
• Oak
• Ash
• Pine

Ash trees have opposite leaves, unlike oaks or maples which may differ.

• Which characteristic distinguishes a conifer from a deciduous tree?
• Needle-like leaves and cones
• Opposite leaves
• Smooth bark
• Deep taproots

Conifers have needle-like leaves and reproduce via cones.

• Which of the following trees is a broadleaf evergreen?
• Oak
• Live Oak
• Maple
• Birch

Live Oak retains its leaves year-round and has broad leaves. 3 / 4

• Which tree is known for producing samaras?
• Pine
• Maple
• Oak
• Elm

Maple trees produce winged seeds called samaras.

• Which feature helps distinguish elm from ash?
• Leaf margins
• Leaf vein pattern
• Flower color
• Bud color

Elm leaves have an asymmetrical base and pinnate veins, unlike ash.Soil and Fertility Management

• What is the primary component of soil that affects aeration and

drainage?

• Organic matter
• Clay content
• Soil texture
• pH

Soil texture (proportion of sand, silt, clay) controls water movement and aeration.

• Which soil pH is optimal for most trees?
• 3.5–4.5
• / 4