ISA Certified Arborist Exam Questions and Correct
Answers (Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary function of xylem in trees?
A. Transport sugars
B. Store nutrients
C. Transport water
D. Produce energy
Answer: C
Xylem is responsible for transporting water and dissolved minerals from
roots to the rest of the tree.
2. Which soil texture has the highest water-holding capacity?
A. Sand
B. Silt
C. Clay
D. Loam
Answer: C
,Clay particles are very small and hold water tightly, giving them the
highest water retention.
3. What is the process by which trees lose water vapor through
leaves?
A. Respiration
B. Transpiration
C. Photosynthesis
D. Evaporation
Answer: B
Transpiration is the loss of water vapor through stomata in leaves.
4. Which part of the tree produces food?
A. Roots
B. Bark
C. Leaves
D. Cambium
Answer: C
Leaves carry out photosynthesis, producing food for the tree.
,5. What is the ideal time to prune most trees?
A. Late spring
B. Early summer
C. Dormant season
D. Fall
Answer: C
Pruning during dormancy minimizes stress and disease risk.
6. What is included bark?
A. Bark trapped between branches
B. Bark peeling off
C. Bark disease
D. Bark growth
Answer: A
Included bark occurs when bark is trapped between branch unions,
weakening structure.
7. Which nutrient deficiency causes chlorosis?
A. Nitrogen
B. Iron
, C. Potassium
D. Calcium
Answer: B
Iron deficiency commonly leads to yellowing between leaf veins.
8. What is the purpose of mulching?
A. Increase soil compaction
B. Retain moisture and regulate temperature
C. Kill insects
D. Increase pH
Answer: B
Mulch conserves moisture and stabilizes soil temperature.
9. What does DBH stand for?
A. Diameter Below Height
B. Diameter at Breast Height
C. Depth Below Height
D. Diameter Branch Height
Answer: B
DBH is a standard measurement taken at 4.5 feet above ground.
Answers (Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary function of xylem in trees?
A. Transport sugars
B. Store nutrients
C. Transport water
D. Produce energy
Answer: C
Xylem is responsible for transporting water and dissolved minerals from
roots to the rest of the tree.
2. Which soil texture has the highest water-holding capacity?
A. Sand
B. Silt
C. Clay
D. Loam
Answer: C
,Clay particles are very small and hold water tightly, giving them the
highest water retention.
3. What is the process by which trees lose water vapor through
leaves?
A. Respiration
B. Transpiration
C. Photosynthesis
D. Evaporation
Answer: B
Transpiration is the loss of water vapor through stomata in leaves.
4. Which part of the tree produces food?
A. Roots
B. Bark
C. Leaves
D. Cambium
Answer: C
Leaves carry out photosynthesis, producing food for the tree.
,5. What is the ideal time to prune most trees?
A. Late spring
B. Early summer
C. Dormant season
D. Fall
Answer: C
Pruning during dormancy minimizes stress and disease risk.
6. What is included bark?
A. Bark trapped between branches
B. Bark peeling off
C. Bark disease
D. Bark growth
Answer: A
Included bark occurs when bark is trapped between branch unions,
weakening structure.
7. Which nutrient deficiency causes chlorosis?
A. Nitrogen
B. Iron
, C. Potassium
D. Calcium
Answer: B
Iron deficiency commonly leads to yellowing between leaf veins.
8. What is the purpose of mulching?
A. Increase soil compaction
B. Retain moisture and regulate temperature
C. Kill insects
D. Increase pH
Answer: B
Mulch conserves moisture and stabilizes soil temperature.
9. What does DBH stand for?
A. Diameter Below Height
B. Diameter at Breast Height
C. Depth Below Height
D. Diameter Branch Height
Answer: B
DBH is a standard measurement taken at 4.5 feet above ground.
