ISA Certified Arborist Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the main function of phloem in trees?
A. Transport water from roots to leaves
B. Store nutrients
C. Transport sugars from leaves to other parts of the tree
D. Provide structural support
Phloem transports the products of photosynthesis, mainly sugars,
from the leaves to roots and other parts of the tree.
2. Which factor most influences a tree’s growth rate?
A. Trunk color
B. Availability of water and nutrients
C. Leaf shape
, D. Bark texture
Water and nutrients are essential for photosynthesis and cellular
growth, directly impacting growth rate.
3. What is the ideal soil pH range for most landscape trees?
A. 3.5–4.5
B. 5.0–5.5
C. 7.5–8.5
D. 6.0–7.0
A slightly acidic to neutral pH allows optimal nutrient availability for
most trees.
4. Which of the following is a primary symptom of girdling roots?
A. Increased leaf size
B. Decline in overall tree health and canopy dieback
C. Excessive flowering
D. Faster growth rate
Girdling roots constrict the trunk or main roots, limiting nutrient and
water transport, causing canopy decline.
5. What is the main purpose of pruning a young tree?
A. Remove all leaves
, B. Develop strong structure and branch framework
C. Stop growth
D. Change species
Proper pruning helps establish a strong, well-structured canopy and
reduces future defects.
6. Which pruning cut removes a branch back to a lateral branch?
A. Heading cut
B. Stub cut
C. Thinning cut
D. Flush cut
Thinning cuts remove a branch back to its point of origin on a larger
branch or trunk without leaving stubs.
7. What is the primary symptom of verticillium wilt in trees?
A. Root knot formation
B. Leaf curling only in spring
C. Wilting, yellowing, and browning of leaves, often branch-specific
D. Formation of mushrooms on bark
Verticillium wilt blocks water movement in vascular tissues, leading
to branch-specific wilting.
, 8. Which tree root type grows mostly horizontally near the soil surface?
A. Taproot
B. Heartroot
C. Lateral roots
D. Fibrous roots
Lateral roots grow outward near the soil surface and provide stability
and nutrient absorption.
9. Which soil texture has the highest water-holding capacity?
A. Sand
B. Clay
C. Silt
D. Gravel
Clay particles are very small and can retain large amounts of water
compared to coarser soils.
10. What is the primary purpose of cabling in tree care?
A. Remove diseased branches
B. Fertilize the tree
C. Support weak or structurally compromised branches
D. Prune roots
Cabling helps stabilize weak branches and reduces risk of failure.
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the main function of phloem in trees?
A. Transport water from roots to leaves
B. Store nutrients
C. Transport sugars from leaves to other parts of the tree
D. Provide structural support
Phloem transports the products of photosynthesis, mainly sugars,
from the leaves to roots and other parts of the tree.
2. Which factor most influences a tree’s growth rate?
A. Trunk color
B. Availability of water and nutrients
C. Leaf shape
, D. Bark texture
Water and nutrients are essential for photosynthesis and cellular
growth, directly impacting growth rate.
3. What is the ideal soil pH range for most landscape trees?
A. 3.5–4.5
B. 5.0–5.5
C. 7.5–8.5
D. 6.0–7.0
A slightly acidic to neutral pH allows optimal nutrient availability for
most trees.
4. Which of the following is a primary symptom of girdling roots?
A. Increased leaf size
B. Decline in overall tree health and canopy dieback
C. Excessive flowering
D. Faster growth rate
Girdling roots constrict the trunk or main roots, limiting nutrient and
water transport, causing canopy decline.
5. What is the main purpose of pruning a young tree?
A. Remove all leaves
, B. Develop strong structure and branch framework
C. Stop growth
D. Change species
Proper pruning helps establish a strong, well-structured canopy and
reduces future defects.
6. Which pruning cut removes a branch back to a lateral branch?
A. Heading cut
B. Stub cut
C. Thinning cut
D. Flush cut
Thinning cuts remove a branch back to its point of origin on a larger
branch or trunk without leaving stubs.
7. What is the primary symptom of verticillium wilt in trees?
A. Root knot formation
B. Leaf curling only in spring
C. Wilting, yellowing, and browning of leaves, often branch-specific
D. Formation of mushrooms on bark
Verticillium wilt blocks water movement in vascular tissues, leading
to branch-specific wilting.
, 8. Which tree root type grows mostly horizontally near the soil surface?
A. Taproot
B. Heartroot
C. Lateral roots
D. Fibrous roots
Lateral roots grow outward near the soil surface and provide stability
and nutrient absorption.
9. Which soil texture has the highest water-holding capacity?
A. Sand
B. Clay
C. Silt
D. Gravel
Clay particles are very small and can retain large amounts of water
compared to coarser soils.
10. What is the primary purpose of cabling in tree care?
A. Remove diseased branches
B. Fertilize the tree
C. Support weak or structurally compromised branches
D. Prune roots
Cabling helps stabilize weak branches and reduces risk of failure.
