ISA CERTIFIED ARBORIST EXAM
QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES
2026 Q&A | INSTANT DOWNLOAD PDF
1. Which of the following is the primary site of photosynthesis in a tree?
A. Bark
B. Roots
C. Flowers
D. Leaves
Leaves contain chlorophyll, which captures sunlight and converts it to
energy through photosynthesis.
2. What is the best pruning time for most deciduous trees?
A. Early summer
B. Late winter to early spring
C. Late summer
D. Fall
Pruning during dormancy reduces stress and the risk of disease.
3. Which type of root system is most common in trees adapted to dry
environments?
A. Fibrous roots
B. Taproots
C. Adventitious roots
D. Deep taproots
Deep taproots allow trees to access water far below the surface.
,4. What is the main function of xylem?
A. Transport sugars
B. Transport water and minerals
C. Store starch
D. Produce hormones
Xylem conducts water and dissolved nutrients from roots to leaves.
5. What is the primary cause of tree girdling roots?
A. Fungal infection
B. Poor pruning
C. Improper planting
D. Over-fertilization
Planting too deep or in confined spaces can cause roots to circle and
strangle the trunk.
6. Which of the following is a characteristic of compound leaves?
A. Single leaf blade
B. Multiple leaflets attached to one petiole
C. Leaf scars on stems
D. Thorn-like structures
Compound leaves have multiple leaflets originating from a single petiole.
7. What is the most common method of tree propagation in commercial
arboriculture?
A. Seed germination
B. Cuttings and grafting
C. Layering
D. Tissue culture
Cuttings and grafting produce genetically identical trees and maintain
desirable traits.
8. What is the main function of phloem?
A. Transport water
B. Transport sugars
C. Store minerals
, D. Support structural integrity
Phloem moves the products of photosynthesis from leaves to roots and
growing tissues.
9. Which of the following soil types drains the fastest?
A. Clay
B. Loam
C. Sand
D. Silt
Sandy soils have large particles, allowing rapid water movement.
10.Which of the following is a symptom of nitrogen deficiency in trees?
A. Necrotic leaf margins
B. Stunted lateral roots
C. Chlorosis of older leaves
D. Excessive flowering
Nitrogen is mobile in plants, so deficiency shows first in older leaves as
yellowing.
11.What is the primary purpose of pruning co-dominant stems?
A. Reduce water uptake
B. Prevent weak unions and storm damage
C. Increase flowering
D. Promote root growth
Co-dominant stems are prone to splitting; pruning reduces risk.
12.Which of the following is a typical symptom of Verticillium wilt?
A. Leaf curl
B. Excessive root growth
C. Wilting and yellowing of leaves on one branch or side
D. Bark cracking
Verticillium wilt often affects only part of the canopy due to vascular
blockage.
QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES
2026 Q&A | INSTANT DOWNLOAD PDF
1. Which of the following is the primary site of photosynthesis in a tree?
A. Bark
B. Roots
C. Flowers
D. Leaves
Leaves contain chlorophyll, which captures sunlight and converts it to
energy through photosynthesis.
2. What is the best pruning time for most deciduous trees?
A. Early summer
B. Late winter to early spring
C. Late summer
D. Fall
Pruning during dormancy reduces stress and the risk of disease.
3. Which type of root system is most common in trees adapted to dry
environments?
A. Fibrous roots
B. Taproots
C. Adventitious roots
D. Deep taproots
Deep taproots allow trees to access water far below the surface.
,4. What is the main function of xylem?
A. Transport sugars
B. Transport water and minerals
C. Store starch
D. Produce hormones
Xylem conducts water and dissolved nutrients from roots to leaves.
5. What is the primary cause of tree girdling roots?
A. Fungal infection
B. Poor pruning
C. Improper planting
D. Over-fertilization
Planting too deep or in confined spaces can cause roots to circle and
strangle the trunk.
6. Which of the following is a characteristic of compound leaves?
A. Single leaf blade
B. Multiple leaflets attached to one petiole
C. Leaf scars on stems
D. Thorn-like structures
Compound leaves have multiple leaflets originating from a single petiole.
7. What is the most common method of tree propagation in commercial
arboriculture?
A. Seed germination
B. Cuttings and grafting
C. Layering
D. Tissue culture
Cuttings and grafting produce genetically identical trees and maintain
desirable traits.
8. What is the main function of phloem?
A. Transport water
B. Transport sugars
C. Store minerals
, D. Support structural integrity
Phloem moves the products of photosynthesis from leaves to roots and
growing tissues.
9. Which of the following soil types drains the fastest?
A. Clay
B. Loam
C. Sand
D. Silt
Sandy soils have large particles, allowing rapid water movement.
10.Which of the following is a symptom of nitrogen deficiency in trees?
A. Necrotic leaf margins
B. Stunted lateral roots
C. Chlorosis of older leaves
D. Excessive flowering
Nitrogen is mobile in plants, so deficiency shows first in older leaves as
yellowing.
11.What is the primary purpose of pruning co-dominant stems?
A. Reduce water uptake
B. Prevent weak unions and storm damage
C. Increase flowering
D. Promote root growth
Co-dominant stems are prone to splitting; pruning reduces risk.
12.Which of the following is a typical symptom of Verticillium wilt?
A. Leaf curl
B. Excessive root growth
C. Wilting and yellowing of leaves on one branch or side
D. Bark cracking
Verticillium wilt often affects only part of the canopy due to vascular
blockage.
