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 function of a tree’s roots?
a) Photosynthesis
b) Absorption of water and nutrients
c) Production of seeds
d) Protection against insects
Roots primarily absorb water and nutrients from the soil,
anchoring the tree and supporting its growth.
2. Which type of tree growth occurs at the tips of branches and
roots?
a) Secondary growth
b) Primary growth
c) Lateral growth
d) Apical dominance
Primary growth occurs at apical meristems, increasing the length
of shoots and roots.
3. What is the ideal soil pH range for most urban trees?
a) 4.0–5.0
b) 5.0–6.0
c) 6.0–7.0
d) 7.5–8.5
Most trees grow best in slightly acidic to neutral soils, allowing
optimal nutrient availability.
,4. Which tree species is most likely to tolerate urban air pollution?
a) Sugar maple
b) Red oak
c) Ginkgo biloba
d) American beech
Ginkgo biloba is highly tolerant to urban pollution, compacted
soils, and adverse growing conditions.
5. What is the primary purpose of pruning young trees?
a) Increase fruit production
b) Develop strong structure
c) Reduce leaf drop
d) Prevent pest infestation
Pruning young trees helps establish strong branch structure,
reducing future hazards.
6. Which of the following is a symptom of overwatering in trees?
a) Leaf scorch
b) Yellowing leaves
c) Early flowering
d) Excessive fruiting
Overwatering can suffocate roots, reducing nutrient uptake and
causing chlorosis.
7. What is the most effective method to prevent the spread of oak
wilt?
a) Spraying leaves with fungicide
b) Avoiding pruning during active beetle periods
c) Applying nitrogen fertilizer
d) Watering deeply
, Oak wilt spreads via root grafts and insect vectors; avoiding
pruning when beetles are active reduces infection.
8. What type of root system do pine trees typically have?
a) Fibrous roots
b) Taproot with lateral roots
c) Adventitious roots
d) Contractile roots
Most pines develop a deep taproot for anchorage, with lateral
roots for nutrient absorption.
9. Which pruning cut removes a branch back to its point of origin
without leaving a stub?
a) Heading cut
b) Thinning cut
c) Lion’s cut
d) Drop cut
A thinning cut removes a branch entirely at its origin, preserving
the tree’s natural shape.
10. What is the best treatment for a girdled tree?
a) Apply fertilizer to the soil
b) Remove constricting materials and support recovery
c) Prune all branches immediately
d) Spray with herbicide
Girdling damages the phloem; removing constrictions and
promoting root and branch recovery is critical.
11. Which of the following trees is most susceptible to Dutch
elm disease?
a) Sugar maple
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. Which of the following is the primary function of a tree’s roots?
a) Photosynthesis
b) Absorption of water and nutrients
c) Production of seeds
d) Protection against insects
Roots primarily absorb water and nutrients from the soil,
anchoring the tree and supporting its growth.
2. Which type of tree growth occurs at the tips of branches and
roots?
a) Secondary growth
b) Primary growth
c) Lateral growth
d) Apical dominance
Primary growth occurs at apical meristems, increasing the length
of shoots and roots.
3. What is the ideal soil pH range for most urban trees?
a) 4.0–5.0
b) 5.0–6.0
c) 6.0–7.0
d) 7.5–8.5
Most trees grow best in slightly acidic to neutral soils, allowing
optimal nutrient availability.
,4. Which tree species is most likely to tolerate urban air pollution?
a) Sugar maple
b) Red oak
c) Ginkgo biloba
d) American beech
Ginkgo biloba is highly tolerant to urban pollution, compacted
soils, and adverse growing conditions.
5. What is the primary purpose of pruning young trees?
a) Increase fruit production
b) Develop strong structure
c) Reduce leaf drop
d) Prevent pest infestation
Pruning young trees helps establish strong branch structure,
reducing future hazards.
6. Which of the following is a symptom of overwatering in trees?
a) Leaf scorch
b) Yellowing leaves
c) Early flowering
d) Excessive fruiting
Overwatering can suffocate roots, reducing nutrient uptake and
causing chlorosis.
7. What is the most effective method to prevent the spread of oak
wilt?
a) Spraying leaves with fungicide
b) Avoiding pruning during active beetle periods
c) Applying nitrogen fertilizer
d) Watering deeply
, Oak wilt spreads via root grafts and insect vectors; avoiding
pruning when beetles are active reduces infection.
8. What type of root system do pine trees typically have?
a) Fibrous roots
b) Taproot with lateral roots
c) Adventitious roots
d) Contractile roots
Most pines develop a deep taproot for anchorage, with lateral
roots for nutrient absorption.
9. Which pruning cut removes a branch back to its point of origin
without leaving a stub?
a) Heading cut
b) Thinning cut
c) Lion’s cut
d) Drop cut
A thinning cut removes a branch entirely at its origin, preserving
the tree’s natural shape.
10. What is the best treatment for a girdled tree?
a) Apply fertilizer to the soil
b) Remove constricting materials and support recovery
c) Prune all branches immediately
d) Spray with herbicide
Girdling damages the phloem; removing constrictions and
promoting root and branch recovery is critical.
11. Which of the following trees is most susceptible to Dutch
elm disease?
a) Sugar maple
