ISA ARBORIST EXAM SCRIPT 2025/2026 QUESTIONS WITH
ANSWERS GRADED A+
✔✔arbuscular mycorrhizae: - ✔✔commonly called endomycorrhizae infects the internal
tree root cells and are most common in deciduous forests.
✔✔armillaria root disease: - ✔✔cause death to trees under all types of stress by
reducing absorption and translocation of water and minerals from the soil to the tree.
✔✔arthropods: - ✔✔microscopic insects and mites that are vital in processing soil
organic matter and mineralizing detritus.
✔✔ascender: - ✔✔attached to the rope, this piece of equipment will grip in one direction
(down) and slide in the other (up) allowing the climber to ascend up the rope in contrast
with descender.
✔✔axial parenchyma - ✔✔cells that run in a vertical direction on the trunk.
✔✔axil - ✔✔the point of attachment of a leaf petiole to a stem.
✔✔back cut - ✔✔a cut made on a tree trunk or branch, opposite from the notch, face
cut, or undercut.
✔✔bacteria - ✔✔organisms that break down organic and inorganic materials such as
fungi, insects, and animals in the soil. They also detoxify harmful substances and adjust
the soil pH. Many also convert nitrogen in the air to a usable form for tree growth.
Bacteria can be found everywhere that life can be supported.
✔✔barrier zone - ✔✔a barrier zone is a chemical boundary within the wood present at
the time of wounding which resist the spread of pathogens.
✔✔balancer - ✔✔a rigging sling(s), usually with at least one spliced eye and a Prusik to
position the load line.
✔✔bark - ✔✔a protective covering on the outside of a tree trunk and made of an outer
periderm and an inner phloem. It keeps moisture and gases in the tree and resists
attack by insects and microorganisms.
✔✔bark distortions - ✔✔overgrown knots, mechanical wounds, holes of all types,
ingrown bark, and other defects which can be seen on the bark appearance.
✔✔bark fissures - ✔✔form on trees whose bark plates only divide in one direction such
as oaks. Some trees, such as beech, do not form fissures because the bark plates
divide in two directions as the tree grows in girth.
,✔✔barrier zone - ✔✔chemical boundary within wood that is present at the time of
wounding and resists the spread of pathogens.
✔✔basal rot or butt rot - ✔✔decay of the lower trunk, flare, or buttress roots, also called
butt rot.
✔✔basic assessment - ✔✔a detailed visual inspection of a tree and the surrounding
site.
✔✔bast fibers - ✔✔elongated, tapering, thick-walled cells that provide strength to wood.
✔✔berry - ✔✔a simple fleshy fruit
✔✔bifurcation - ✔✔the natural division of a branch or stem into two or more stems.
✔✔bimetallic connector: - ✔✔the connector on a lightning protection system consisting
of two or more types of metals intended to reduce the likelihood of forming an
electrolytic couple.
✔✔biological control management: - ✔✔the management of pests using organisms that
focus on control of plant competition, allelopathy, animals, insects, or pathogens.
✔✔biomass - ✔✔a mass that contains some form of living cells.
✔✔biorational pesticide - ✔✔a pesticide formulated from naturally occurring plant
extracts, microbes, or microbial byproducts.
✔✔biostimulant - ✔✔any substance or microorganism applied to plants with the aim to
enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits,
regardless of its nutrients content.
✔✔biotic - ✔✔pertaining to living organisms and their ecological and physiological
relations.
✔✔bleeding - ✔✔the flow of sap from plant wounds.
✔✔blight - ✔✔any disease that kills young plant tissues.
✔✔block and tackle - ✔✔a system of two or more pulleys and rope used to lift or pull
heavy loads.
with rotating sheaves with bearing and bushing to reduce friction
✔✔bole - ✔✔the main trunk of a tree below the branches.
,✔✔bore cut - ✔✔using the tip of a chain saw to cut into or through the middle of a piece
of wood.
✔✔botanicals: - ✔✔compounds and pesticides made from plants.
✔✔bracing - ✔✔the installation of screws, cables, threaded-steel rods in branches,
leaders, or trunks to provide supplemental support and to reduce the probability of
failure of one or more parts of the tree.
✔✔bract - ✔✔a modified leaf that compliments the flower.
✔✔branch collar - ✔✔the swollen area of bark at the underside of a branch.
✔✔branch bark ridge - ✔✔the raised area of bark at the top of the branch union that
marks where the smaller branch and parent branch meet.
✔✔branch bark ridge and branch collar - ✔✔the natural features of a fork or union that
consist of raised bark but may or may not be obvious. Neither the branch bark ridge nor
collar should be cut when pruning the tree.
✔✔bridge graft - ✔✔the method to used to repair a girdled trunk in which scion wood is
grafted above and below the injury to reconnect the trunk vascular cambium.
✔✔bollards - ✔✔friction device-posts strapped to a tree for taking wraps with a load line
✔✔buds - ✔✔organs that contain preformed parts of leaves or needles, flowers, or
both. Buds are structures that are made up of embryonic shoots.
✔✔balance the limb (with a second rope) - ✔✔branch removal involving a second rope
to reduce swing and dynamic loading
✔✔butt tied vs tip tied - ✔✔rigging line is tied to the butt end of the branch vs rigging
lined tied to the tip end .
✔✔buffering capacity - ✔✔the ability of a soil to maintain its pH.
✔✔bulk density - ✔✔the mass of soil per unit volume used as a measure of compaction.
✔✔buttress roots (hydrotropic roots) - ✔✔the lateral surface roots that aid in stabilizing
a tree.
✔✔cambium - ✔✔a cellular plant tissue from which phloem, xylem, or cork grows by
division, resulting (in woody plants) in secondary thickening.
, Xylem- inside
Phloem- outside
-layer between the phloem and the xylem
✔✔cork cambium - ✔✔produces bark or peridium
✔✔cable aid - ✔✔a tool used mainly to tighten lag hooks and eye-bolts into a tree.
✔✔carabiners (screw links) - ✔✔type of connection link in tree climbing
- always loaded along their major axis and never across the gate
✔✔cable clamp - ✔✔should be used to attach small diameter cable to anchor hardware.
There should be at least 3 clamps per anchor and the "U" of the clamp goes on the
short end of the cable.
✔✔cable end termination - ✔✔the hardware designed to anchor cables installed
through a branch or stem.
✔✔cable grip - ✔✔a mechanical device that temporarily grasps and holds wire rope or
strand cable during installation.
✔✔cabling - ✔✔the installation of a steel wire rope or synthetic-fiber rope within a tree
to provide supplemental sup-port to branches with weak unions, heavy branches, and
weak wooded species that may pose a threat of failure.
✔✔caliper - ✔✔tree trunk diameter measured 6 in. (15 cm) above the flare; if the caliper
is greater than 4 in. (10 cm), the measurement is taken at 12 in. (30 cm) above the flare.
✔✔cambium or cambial zone - ✔✔a layer of trunk cells that produce xylem on the inner
side and phloem or inner bark on the outer side.
-produce cells that become xylem,phloem or cambium
✔✔canker - ✔✔a definite, relatively localized lesion, primarily of bark and wood.
✔✔capillary water - ✔✔the water held in the capillary pores of soil.
✔✔capsule - ✔✔a simple, dry, fruit.
✔✔carbon dioxide - ✔✔a colorless gas, soluble in water, used by green plants to make
carbohydrates during photosynthesis.
ANSWERS GRADED A+
✔✔arbuscular mycorrhizae: - ✔✔commonly called endomycorrhizae infects the internal
tree root cells and are most common in deciduous forests.
✔✔armillaria root disease: - ✔✔cause death to trees under all types of stress by
reducing absorption and translocation of water and minerals from the soil to the tree.
✔✔arthropods: - ✔✔microscopic insects and mites that are vital in processing soil
organic matter and mineralizing detritus.
✔✔ascender: - ✔✔attached to the rope, this piece of equipment will grip in one direction
(down) and slide in the other (up) allowing the climber to ascend up the rope in contrast
with descender.
✔✔axial parenchyma - ✔✔cells that run in a vertical direction on the trunk.
✔✔axil - ✔✔the point of attachment of a leaf petiole to a stem.
✔✔back cut - ✔✔a cut made on a tree trunk or branch, opposite from the notch, face
cut, or undercut.
✔✔bacteria - ✔✔organisms that break down organic and inorganic materials such as
fungi, insects, and animals in the soil. They also detoxify harmful substances and adjust
the soil pH. Many also convert nitrogen in the air to a usable form for tree growth.
Bacteria can be found everywhere that life can be supported.
✔✔barrier zone - ✔✔a barrier zone is a chemical boundary within the wood present at
the time of wounding which resist the spread of pathogens.
✔✔balancer - ✔✔a rigging sling(s), usually with at least one spliced eye and a Prusik to
position the load line.
✔✔bark - ✔✔a protective covering on the outside of a tree trunk and made of an outer
periderm and an inner phloem. It keeps moisture and gases in the tree and resists
attack by insects and microorganisms.
✔✔bark distortions - ✔✔overgrown knots, mechanical wounds, holes of all types,
ingrown bark, and other defects which can be seen on the bark appearance.
✔✔bark fissures - ✔✔form on trees whose bark plates only divide in one direction such
as oaks. Some trees, such as beech, do not form fissures because the bark plates
divide in two directions as the tree grows in girth.
,✔✔barrier zone - ✔✔chemical boundary within wood that is present at the time of
wounding and resists the spread of pathogens.
✔✔basal rot or butt rot - ✔✔decay of the lower trunk, flare, or buttress roots, also called
butt rot.
✔✔basic assessment - ✔✔a detailed visual inspection of a tree and the surrounding
site.
✔✔bast fibers - ✔✔elongated, tapering, thick-walled cells that provide strength to wood.
✔✔berry - ✔✔a simple fleshy fruit
✔✔bifurcation - ✔✔the natural division of a branch or stem into two or more stems.
✔✔bimetallic connector: - ✔✔the connector on a lightning protection system consisting
of two or more types of metals intended to reduce the likelihood of forming an
electrolytic couple.
✔✔biological control management: - ✔✔the management of pests using organisms that
focus on control of plant competition, allelopathy, animals, insects, or pathogens.
✔✔biomass - ✔✔a mass that contains some form of living cells.
✔✔biorational pesticide - ✔✔a pesticide formulated from naturally occurring plant
extracts, microbes, or microbial byproducts.
✔✔biostimulant - ✔✔any substance or microorganism applied to plants with the aim to
enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits,
regardless of its nutrients content.
✔✔biotic - ✔✔pertaining to living organisms and their ecological and physiological
relations.
✔✔bleeding - ✔✔the flow of sap from plant wounds.
✔✔blight - ✔✔any disease that kills young plant tissues.
✔✔block and tackle - ✔✔a system of two or more pulleys and rope used to lift or pull
heavy loads.
with rotating sheaves with bearing and bushing to reduce friction
✔✔bole - ✔✔the main trunk of a tree below the branches.
,✔✔bore cut - ✔✔using the tip of a chain saw to cut into or through the middle of a piece
of wood.
✔✔botanicals: - ✔✔compounds and pesticides made from plants.
✔✔bracing - ✔✔the installation of screws, cables, threaded-steel rods in branches,
leaders, or trunks to provide supplemental support and to reduce the probability of
failure of one or more parts of the tree.
✔✔bract - ✔✔a modified leaf that compliments the flower.
✔✔branch collar - ✔✔the swollen area of bark at the underside of a branch.
✔✔branch bark ridge - ✔✔the raised area of bark at the top of the branch union that
marks where the smaller branch and parent branch meet.
✔✔branch bark ridge and branch collar - ✔✔the natural features of a fork or union that
consist of raised bark but may or may not be obvious. Neither the branch bark ridge nor
collar should be cut when pruning the tree.
✔✔bridge graft - ✔✔the method to used to repair a girdled trunk in which scion wood is
grafted above and below the injury to reconnect the trunk vascular cambium.
✔✔bollards - ✔✔friction device-posts strapped to a tree for taking wraps with a load line
✔✔buds - ✔✔organs that contain preformed parts of leaves or needles, flowers, or
both. Buds are structures that are made up of embryonic shoots.
✔✔balance the limb (with a second rope) - ✔✔branch removal involving a second rope
to reduce swing and dynamic loading
✔✔butt tied vs tip tied - ✔✔rigging line is tied to the butt end of the branch vs rigging
lined tied to the tip end .
✔✔buffering capacity - ✔✔the ability of a soil to maintain its pH.
✔✔bulk density - ✔✔the mass of soil per unit volume used as a measure of compaction.
✔✔buttress roots (hydrotropic roots) - ✔✔the lateral surface roots that aid in stabilizing
a tree.
✔✔cambium - ✔✔a cellular plant tissue from which phloem, xylem, or cork grows by
division, resulting (in woody plants) in secondary thickening.
, Xylem- inside
Phloem- outside
-layer between the phloem and the xylem
✔✔cork cambium - ✔✔produces bark or peridium
✔✔cable aid - ✔✔a tool used mainly to tighten lag hooks and eye-bolts into a tree.
✔✔carabiners (screw links) - ✔✔type of connection link in tree climbing
- always loaded along their major axis and never across the gate
✔✔cable clamp - ✔✔should be used to attach small diameter cable to anchor hardware.
There should be at least 3 clamps per anchor and the "U" of the clamp goes on the
short end of the cable.
✔✔cable end termination - ✔✔the hardware designed to anchor cables installed
through a branch or stem.
✔✔cable grip - ✔✔a mechanical device that temporarily grasps and holds wire rope or
strand cable during installation.
✔✔cabling - ✔✔the installation of a steel wire rope or synthetic-fiber rope within a tree
to provide supplemental sup-port to branches with weak unions, heavy branches, and
weak wooded species that may pose a threat of failure.
✔✔caliper - ✔✔tree trunk diameter measured 6 in. (15 cm) above the flare; if the caliper
is greater than 4 in. (10 cm), the measurement is taken at 12 in. (30 cm) above the flare.
✔✔cambium or cambial zone - ✔✔a layer of trunk cells that produce xylem on the inner
side and phloem or inner bark on the outer side.
-produce cells that become xylem,phloem or cambium
✔✔canker - ✔✔a definite, relatively localized lesion, primarily of bark and wood.
✔✔capillary water - ✔✔the water held in the capillary pores of soil.
✔✔capsule - ✔✔a simple, dry, fruit.
✔✔carbon dioxide - ✔✔a colorless gas, soluble in water, used by green plants to make
carbohydrates during photosynthesis.
