International Society of
MAXE · ASI
Arboriculture
✦ ✦
ISA Certified Arborist Program
EST. 1924
P R O M O T I N G T H E P R O F E S S I O N A L P R A C T I C E O F A R B O R I C U LT U R E
ISA Certified Arborist
T R E E B I O LO G Y, S O I L S C I E N C E , W AT E R M A N AG E M E N T & N U T R I T I O N
INSTITUTION International Society of PROGRAM ISA Certified Arborist Certification
Arboriculture (ISA)
COURSE CODE ISA — Certification Exam COURSE TITLE Arboriculture — Comprehensive
Certification
ACADEMIC YEAR EXAM TITLE ISA Certified Arborist
TOTAL QUESTIONS 91 Questions FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question unless otherwise instructed.
▸ Tree biology, plant identification, soil science, water management, and nutrition are all testable content.
▸ Correct answers and detailed rationales appear below each question for study purposes.
▸ All content is derived from ISA Certified Arborist study materials.
, SECTION I — TREE BIOLOGY, IDENTIFICATION, SOIL,
Questions 1 – 91
WATER & NUTRITION
1. A characteristic of sandy soils in arid regions is that they:
A. Have high organic matter content naturally
B. Tend to become alkaline, and salts build up due to lack of heavy rainfall
C. Are always acidic due to rapid leaching
D. Hold water better than clay soils
CORRECT ANSWER B — Tend to become alkaline, and salts build up due to lack of heavy
rainfall
RATIONALE In arid regions, limited rainfall prevents leaching of soluble salts and carbonates,
causing sandy soils to become alkaline over time. Salts accumulate because there
is insufficient water to wash them through the soil profile. This is a key
consideration for arborists working in dry climates.
2. What is the loss of water vapor from the leaves called?
A. Respiration
B. Osmosis
C. Transpiration
D. Photosynthesis
CORRECT ANSWER C — Transpiration
RATIONALE Transpiration is the evaporative loss of water vapor from leaves, primarily through
stomata. This process creates the tension that pulls water upward through the
xylem and provides evaporative cooling. Respiration (A) releases energy from
food. Osmosis (B) is water entry into roots. Photosynthesis (D) produces food.
,3. Select the scientific name that is written correctly:
A. Quercus Rubra
B. Quercus rubra
C. quercus Rubra
D. quercus rubra
CORRECT ANSWER B — Quercus rubra
RATIONALE Scientific names follow binomial nomenclature: the genus is capitalized
(Quercus) and the specific epithet is lowercase (rubra). Both should be italicized
or underlined. Option A has the species capitalized incorrectly. Options C and D
fail to capitalize the genus name.
4. The climatic factor that determines hardiness zones is:
A. Annual rainfall totals
B. Low temperature extremes
C. Growing season length
D. Wind exposure
CORRECT ANSWER B — Low temperature extremes
RATIONALE USDA Hardiness Zones are primarily based on average annual minimum winter
temperatures. This indicates which plants can survive the coldest temperatures in
a given geographic area. While rainfall (A), growing season (C), and wind (D) affect
plant health, they do not define hardiness zones.
, 5. What process combines carbon dioxide and water in a reaction driven by light to produce
sugars, with oxygen as a product?
A. Respiration
B. Transpiration
C. Photosynthesis
D. Osmosis
CORRECT ANSWER C — Photosynthesis
RATIONALE Photosynthesis is the process: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂. Carbon
dioxide and water combine using light energy captured by chlorophyll to produce
glucose (sugar) and oxygen. Respiration (A) is the reverse process. Transpiration
(B) is water loss. Osmosis (D) is water movement.
6. In 1 foot (0.3 m) of clay soil with 4 inches (10 cm) of water in the soil, approximately how
many inches of water would be available to the tree?
A. Four inches
B. Two inches
C. One inch
D. Half an inch
CORRECT ANSWER C — One inch
RATIONALE In clay soil, much of the water is held tightly in micropores and is unavailable to
plants. Of the total water present, only a fraction is available for root uptake.
Approximately 1 inch of the 4 inches would be available, with the rest being
hygroscopic water (too tightly bound) or gravitational water (already drained).
MAXE · ASI
Arboriculture
✦ ✦
ISA Certified Arborist Program
EST. 1924
P R O M O T I N G T H E P R O F E S S I O N A L P R A C T I C E O F A R B O R I C U LT U R E
ISA Certified Arborist
T R E E B I O LO G Y, S O I L S C I E N C E , W AT E R M A N AG E M E N T & N U T R I T I O N
INSTITUTION International Society of PROGRAM ISA Certified Arborist Certification
Arboriculture (ISA)
COURSE CODE ISA — Certification Exam COURSE TITLE Arboriculture — Comprehensive
Certification
ACADEMIC YEAR EXAM TITLE ISA Certified Arborist
TOTAL QUESTIONS 91 Questions FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question unless otherwise instructed.
▸ Tree biology, plant identification, soil science, water management, and nutrition are all testable content.
▸ Correct answers and detailed rationales appear below each question for study purposes.
▸ All content is derived from ISA Certified Arborist study materials.
, SECTION I — TREE BIOLOGY, IDENTIFICATION, SOIL,
Questions 1 – 91
WATER & NUTRITION
1. A characteristic of sandy soils in arid regions is that they:
A. Have high organic matter content naturally
B. Tend to become alkaline, and salts build up due to lack of heavy rainfall
C. Are always acidic due to rapid leaching
D. Hold water better than clay soils
CORRECT ANSWER B — Tend to become alkaline, and salts build up due to lack of heavy
rainfall
RATIONALE In arid regions, limited rainfall prevents leaching of soluble salts and carbonates,
causing sandy soils to become alkaline over time. Salts accumulate because there
is insufficient water to wash them through the soil profile. This is a key
consideration for arborists working in dry climates.
2. What is the loss of water vapor from the leaves called?
A. Respiration
B. Osmosis
C. Transpiration
D. Photosynthesis
CORRECT ANSWER C — Transpiration
RATIONALE Transpiration is the evaporative loss of water vapor from leaves, primarily through
stomata. This process creates the tension that pulls water upward through the
xylem and provides evaporative cooling. Respiration (A) releases energy from
food. Osmosis (B) is water entry into roots. Photosynthesis (D) produces food.
,3. Select the scientific name that is written correctly:
A. Quercus Rubra
B. Quercus rubra
C. quercus Rubra
D. quercus rubra
CORRECT ANSWER B — Quercus rubra
RATIONALE Scientific names follow binomial nomenclature: the genus is capitalized
(Quercus) and the specific epithet is lowercase (rubra). Both should be italicized
or underlined. Option A has the species capitalized incorrectly. Options C and D
fail to capitalize the genus name.
4. The climatic factor that determines hardiness zones is:
A. Annual rainfall totals
B. Low temperature extremes
C. Growing season length
D. Wind exposure
CORRECT ANSWER B — Low temperature extremes
RATIONALE USDA Hardiness Zones are primarily based on average annual minimum winter
temperatures. This indicates which plants can survive the coldest temperatures in
a given geographic area. While rainfall (A), growing season (C), and wind (D) affect
plant health, they do not define hardiness zones.
, 5. What process combines carbon dioxide and water in a reaction driven by light to produce
sugars, with oxygen as a product?
A. Respiration
B. Transpiration
C. Photosynthesis
D. Osmosis
CORRECT ANSWER C — Photosynthesis
RATIONALE Photosynthesis is the process: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂. Carbon
dioxide and water combine using light energy captured by chlorophyll to produce
glucose (sugar) and oxygen. Respiration (A) is the reverse process. Transpiration
(B) is water loss. Osmosis (D) is water movement.
6. In 1 foot (0.3 m) of clay soil with 4 inches (10 cm) of water in the soil, approximately how
many inches of water would be available to the tree?
A. Four inches
B. Two inches
C. One inch
D. Half an inch
CORRECT ANSWER C — One inch
RATIONALE In clay soil, much of the water is held tightly in micropores and is unavailable to
plants. Of the total water present, only a fraction is available for root uptake.
Approximately 1 inch of the 4 inches would be available, with the rest being
hygroscopic water (too tightly bound) or gravitational water (already drained).
