Page 1 of 165
ISA ARBORIST CERTIFICATION EXAM TEST
BANK () QUESTIONS AND
VERIFIED RATIONALIZED ANSWERS, 100%
PASSING SCORE GUARANTEED
||COMPLETE A+ GUIDE
Q1. Where does most of a tree’s woody biomass (dry weight)
come from?
A) Water absorbed by roots
B) Minerals from soil
C) Carbon dioxide from air
D) Organic matter in soil
Answer: C) Carbon dioxide from air
Rationale: Through photosynthesis, trees convert atmospheric
,Page 2 of 165
CO₂ into carbohydrates. Minerals and water contribute less
than 5% of dry mass.
Q2. Which tissue is responsible for lateral growth (increase in
girth)?
A) Apical meristem
B) Vascular cambium
C) Cork cambium
D) Xylem
Answer: B) Vascular cambium
Rationale: Apical meristem produces height growth; vascular
cambium produces secondary xylem (wood) inward and
phloem outward.
Q3. What is the primary function of heartwood?
A) Water conduction
B) Nutrient storage
C) Structural support
D) Photosynthesis
,Page 3 of 165
Answer: C) Structural support
Rationale: Heartwood is dead, darkened wood filled with
extractives that provide decay resistance and mechanical
strength. Water conduction occurs in sapwood.
Q4. Which cells are responsible for water transport in
hardwoods?
A) Tracheids
B) Vessel elements
C) Sieve tube elements
D) Fibers
Answer: B) Vessel elements
Rationale: Hardwoods have vessels (larger diameter, more
efficient). Conifers use tracheids.
Q5. The function of lenticels is:
A) Gas exchange
B) Water absorption
, Page 4 of 165
C) Insect defense
D) Photosynthesis
Answer: A) Gas exchange
Rationale: Lenticels allow oxygen and carbon dioxide to pass
through bark for living inner bark cells.
Q6. What does CODIT stand for?
A) Compartmentalization of Decay in Trees
B) Complete Oak Decay Identification Test
C) Control of Dieback in Timber
D) Conifer Decay Isolation Technique
Answer: A) Compartmentalization of Decay in Trees
Rationale: CODIT describes how trees chemically and
physically wall off decay after wounding.
Q7. A tree’s root system typically extends how far from the
trunk?
A) Equal to the drip line
B) 1–2 times the drip line
ISA ARBORIST CERTIFICATION EXAM TEST
BANK () QUESTIONS AND
VERIFIED RATIONALIZED ANSWERS, 100%
PASSING SCORE GUARANTEED
||COMPLETE A+ GUIDE
Q1. Where does most of a tree’s woody biomass (dry weight)
come from?
A) Water absorbed by roots
B) Minerals from soil
C) Carbon dioxide from air
D) Organic matter in soil
Answer: C) Carbon dioxide from air
Rationale: Through photosynthesis, trees convert atmospheric
,Page 2 of 165
CO₂ into carbohydrates. Minerals and water contribute less
than 5% of dry mass.
Q2. Which tissue is responsible for lateral growth (increase in
girth)?
A) Apical meristem
B) Vascular cambium
C) Cork cambium
D) Xylem
Answer: B) Vascular cambium
Rationale: Apical meristem produces height growth; vascular
cambium produces secondary xylem (wood) inward and
phloem outward.
Q3. What is the primary function of heartwood?
A) Water conduction
B) Nutrient storage
C) Structural support
D) Photosynthesis
,Page 3 of 165
Answer: C) Structural support
Rationale: Heartwood is dead, darkened wood filled with
extractives that provide decay resistance and mechanical
strength. Water conduction occurs in sapwood.
Q4. Which cells are responsible for water transport in
hardwoods?
A) Tracheids
B) Vessel elements
C) Sieve tube elements
D) Fibers
Answer: B) Vessel elements
Rationale: Hardwoods have vessels (larger diameter, more
efficient). Conifers use tracheids.
Q5. The function of lenticels is:
A) Gas exchange
B) Water absorption
, Page 4 of 165
C) Insect defense
D) Photosynthesis
Answer: A) Gas exchange
Rationale: Lenticels allow oxygen and carbon dioxide to pass
through bark for living inner bark cells.
Q6. What does CODIT stand for?
A) Compartmentalization of Decay in Trees
B) Complete Oak Decay Identification Test
C) Control of Dieback in Timber
D) Conifer Decay Isolation Technique
Answer: A) Compartmentalization of Decay in Trees
Rationale: CODIT describes how trees chemically and
physically wall off decay after wounding.
Q7. A tree’s root system typically extends how far from the
trunk?
A) Equal to the drip line
B) 1–2 times the drip line
