ISA Certified Arborist Practice Exam
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
Tree Biology and Physiology
1. Which layer of a tree is primarily responsible for water transport?
A. Phloem
B. Cambium
C. Xylem
D. Bark
Xylem transports water and minerals from the roots to the leaves.
2. Which plant hormone is primarily responsible for promoting cell
elongation?
A. Ethylene
B. Auxin
C. Gibberellin
, D. Cytokinin
Auxin promotes cell elongation, especially in stems and young
shoots.
3. Which part of the tree produces new xylem and phloem each year?
A. Bark
B. Cambium
C. Pith
D. Cortex
The cambium is a layer of dividing cells that generates xylem inward
and phloem outward.
4. What is the primary function of phloem?
A. Water absorption
B. Nutrient storage
C. Transport of sugars
D. Structural support
Phloem transports sugars produced in leaves to other parts of the
plant.
5. What type of root system is characterized by a single dominant
taproot?
A. Taproot system
B. Fibrous root system
C. Adventitious roots
D. Buttress roots
, Taproots have one main root that grows downward, typical of many
trees.
Tree Identification
6. Which leaf arrangement is opposite?
A. Maple
B. Oak
C. Ash
D. Pine
Ash trees have opposite leaves, unlike oaks or maples which may
differ.
7. Which characteristic distinguishes a conifer from a deciduous tree?
A. Needle-like leaves and cones
B. Opposite leaves
C. Smooth bark
D. Deep taproots
Conifers have needle-like leaves and reproduce via cones.
8. Which of the following trees is a broadleaf evergreen?
A. Oak
B. Live Oak
C. Maple
D. Birch
Live Oak retains its leaves year-round and has broad leaves.
, 9. Which tree is known for producing samaras?
A. Pine
B. Maple
C. Oak
D. Elm
Maple trees produce winged seeds called samaras.
10. Which feature helps distinguish elm from ash?
A. Leaf margins
B. Leaf vein pattern
C. Flower color
D. Bud color
Elm leaves have an asymmetrical base and pinnate veins, unlike ash.
Soil and Fertility Management
11. What is the primary component of soil that affects aeration and
drainage?
A. Organic matter
B. Clay content
C. Soil texture
D. pH
Soil texture (proportion of sand, silt, clay) controls water movement
and aeration.
12. Which soil pH is optimal for most trees?
A. 3.5–4.5
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
Tree Biology and Physiology
1. Which layer of a tree is primarily responsible for water transport?
A. Phloem
B. Cambium
C. Xylem
D. Bark
Xylem transports water and minerals from the roots to the leaves.
2. Which plant hormone is primarily responsible for promoting cell
elongation?
A. Ethylene
B. Auxin
C. Gibberellin
, D. Cytokinin
Auxin promotes cell elongation, especially in stems and young
shoots.
3. Which part of the tree produces new xylem and phloem each year?
A. Bark
B. Cambium
C. Pith
D. Cortex
The cambium is a layer of dividing cells that generates xylem inward
and phloem outward.
4. What is the primary function of phloem?
A. Water absorption
B. Nutrient storage
C. Transport of sugars
D. Structural support
Phloem transports sugars produced in leaves to other parts of the
plant.
5. What type of root system is characterized by a single dominant
taproot?
A. Taproot system
B. Fibrous root system
C. Adventitious roots
D. Buttress roots
, Taproots have one main root that grows downward, typical of many
trees.
Tree Identification
6. Which leaf arrangement is opposite?
A. Maple
B. Oak
C. Ash
D. Pine
Ash trees have opposite leaves, unlike oaks or maples which may
differ.
7. Which characteristic distinguishes a conifer from a deciduous tree?
A. Needle-like leaves and cones
B. Opposite leaves
C. Smooth bark
D. Deep taproots
Conifers have needle-like leaves and reproduce via cones.
8. Which of the following trees is a broadleaf evergreen?
A. Oak
B. Live Oak
C. Maple
D. Birch
Live Oak retains its leaves year-round and has broad leaves.
, 9. Which tree is known for producing samaras?
A. Pine
B. Maple
C. Oak
D. Elm
Maple trees produce winged seeds called samaras.
10. Which feature helps distinguish elm from ash?
A. Leaf margins
B. Leaf vein pattern
C. Flower color
D. Bud color
Elm leaves have an asymmetrical base and pinnate veins, unlike ash.
Soil and Fertility Management
11. What is the primary component of soil that affects aeration and
drainage?
A. Organic matter
B. Clay content
C. Soil texture
D. pH
Soil texture (proportion of sand, silt, clay) controls water movement
and aeration.
12. Which soil pH is optimal for most trees?
A. 3.5–4.5
