ISA ARBORIST EXAM 191 2026 QUESTIONS
WITH SOLUTIONS GRADED A+
◉ 7-Strand, Common Grade Cable. Answer: Steel-cable construction
in which seven strands are twisted together in a spiral pattern. Used
to add supplemental structural support to trees.
◉ 12-Strand Rope. Answer: For arborist ropes, a braided rope
consisting of 12 strands. Most are coreless.
◉ What are the two types of 12 strand ropes?. Answer: Tight braid
and loose braid.
◉ Tight Braid. Answer: It is not easily spliceable, used for climbing
and rigging lines.
◉ Loose Braid. Answer: Easily spliceable braid, commonly used for
slings.
◉ 16-Strand Rope. Answer: For arborist ropes, a braided rope that
has a 16-strand, load-bearing cover and a filler core that is not
significant in load carrying.
,◉ 24-Strand Rope. Answer: For arborist ropes, a braided rope that
has a 24-strand cover and is available in double braid or kernmantle
construction.
◉ Abiotic Disorder. Answer: Plant malady caused by nonliving,
environmental, or man-made agents.
◉ Abscission Zone. Answer: Area at the base of the petiole where
cellular breakdown leads to leaf and fruit drop.
◉ Absorbing Roots. Answer: Fine, fibrous roots that take up water
and minerals. Most are within the top 12 inches of soil.
◉ Access Line. Answer: 1) Second climbing line hung in a tree in
case it is needed to reach a victim in an emergency. 2) Climbing line
installed in a tree to gain access to, but not use to work in, the tree.
◉ Access Route. Answer: Defined entrance and exit route for a
property during construction, tree work, or landscape operations.
◉ Acclimation. Answer: Physiological adaption process of plants and
other living organisms to a climate or environment different from
their native environment or where originally grown.
,◉ Actinomycetes. Answer: Group of soil bacteria resembling fungi.
Actinomycetes play a role in the decomposition of organic matter
and the release of mineral elements.
◉ Action Threshold. Answer: Pest population or plant damage level
that requires action to prevent irreversible or unacceptable
physiological and/or aesthetic harm.
◉ Acute. Answer: Disorder or disease that occurs suddenly or over a
short period of time. Contrast with chronic.
◉ Adaptability. Answer: Genetic ability of plants and other living
organisms to adjust or acclimate to different environments.
◉ Adventitious Bud. Answer: Bud arising from a place other than a
leaf axil or shoot tip, usually as a result of hormonal triggers.
◉ Aerial Rescue. Answer: Method of bringing an injured worker
down from a tree or aerial lift device.
◉ Aerial Roots. Answer: Aboveground roots. Usually adventitious in
nature and sometimes having unique adaptive functions.
, ◉ Aerobic. Answer: With oxygen. Process that occurs in the
presence of oxygen.
◉ Aggregate. Answer: 1) Close cluster or mix of small particles of
soil and/or organic matter of varying sizes that are bonded together;
sand, gravel, or small rocks in soil; and/or sand, gravel, or small
rocks used under paved surfaces.
◉ Aggregate. Answer: Clusters of flowers or fruits that appear as a
single unit.
◉ Aggregate. Answer: Individual tree crowns that form a canopy.
◉ Air Excavation Device, Air Excavator. Answer: Device that directs a
jet of highly compressed air to excavate soil.
◉ When is an air excavation device used?. Answer: Used within the
root zone of trees to avoid or minimize damage to the roots, or near
underground structures such as pipes and wires to avoid or
minimize damage to them.
◉ Air Terminal. Answer: Uppermost point of a tree lighting
protection system.
WITH SOLUTIONS GRADED A+
◉ 7-Strand, Common Grade Cable. Answer: Steel-cable construction
in which seven strands are twisted together in a spiral pattern. Used
to add supplemental structural support to trees.
◉ 12-Strand Rope. Answer: For arborist ropes, a braided rope
consisting of 12 strands. Most are coreless.
◉ What are the two types of 12 strand ropes?. Answer: Tight braid
and loose braid.
◉ Tight Braid. Answer: It is not easily spliceable, used for climbing
and rigging lines.
◉ Loose Braid. Answer: Easily spliceable braid, commonly used for
slings.
◉ 16-Strand Rope. Answer: For arborist ropes, a braided rope that
has a 16-strand, load-bearing cover and a filler core that is not
significant in load carrying.
,◉ 24-Strand Rope. Answer: For arborist ropes, a braided rope that
has a 24-strand cover and is available in double braid or kernmantle
construction.
◉ Abiotic Disorder. Answer: Plant malady caused by nonliving,
environmental, or man-made agents.
◉ Abscission Zone. Answer: Area at the base of the petiole where
cellular breakdown leads to leaf and fruit drop.
◉ Absorbing Roots. Answer: Fine, fibrous roots that take up water
and minerals. Most are within the top 12 inches of soil.
◉ Access Line. Answer: 1) Second climbing line hung in a tree in
case it is needed to reach a victim in an emergency. 2) Climbing line
installed in a tree to gain access to, but not use to work in, the tree.
◉ Access Route. Answer: Defined entrance and exit route for a
property during construction, tree work, or landscape operations.
◉ Acclimation. Answer: Physiological adaption process of plants and
other living organisms to a climate or environment different from
their native environment or where originally grown.
,◉ Actinomycetes. Answer: Group of soil bacteria resembling fungi.
Actinomycetes play a role in the decomposition of organic matter
and the release of mineral elements.
◉ Action Threshold. Answer: Pest population or plant damage level
that requires action to prevent irreversible or unacceptable
physiological and/or aesthetic harm.
◉ Acute. Answer: Disorder or disease that occurs suddenly or over a
short period of time. Contrast with chronic.
◉ Adaptability. Answer: Genetic ability of plants and other living
organisms to adjust or acclimate to different environments.
◉ Adventitious Bud. Answer: Bud arising from a place other than a
leaf axil or shoot tip, usually as a result of hormonal triggers.
◉ Aerial Rescue. Answer: Method of bringing an injured worker
down from a tree or aerial lift device.
◉ Aerial Roots. Answer: Aboveground roots. Usually adventitious in
nature and sometimes having unique adaptive functions.
, ◉ Aerobic. Answer: With oxygen. Process that occurs in the
presence of oxygen.
◉ Aggregate. Answer: 1) Close cluster or mix of small particles of
soil and/or organic matter of varying sizes that are bonded together;
sand, gravel, or small rocks in soil; and/or sand, gravel, or small
rocks used under paved surfaces.
◉ Aggregate. Answer: Clusters of flowers or fruits that appear as a
single unit.
◉ Aggregate. Answer: Individual tree crowns that form a canopy.
◉ Air Excavation Device, Air Excavator. Answer: Device that directs a
jet of highly compressed air to excavate soil.
◉ When is an air excavation device used?. Answer: Used within the
root zone of trees to avoid or minimize damage to the roots, or near
underground structures such as pipes and wires to avoid or
minimize damage to them.
◉ Air Terminal. Answer: Uppermost point of a tree lighting
protection system.
