ISA Certified Arborist Practice Exam
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
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
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
