©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Arborist ISA Review Exam Questions
and Answers 100% Solved | Graded A+
abiotic - ✔✔pertaining to the nonliving parts of an ecosystem, such as soil
particles, bedrock, air, water.
abscisic acid (ABA) - ✔✔a plant hormone that stimulates stomatal closure
and promotes seed and bud dormancy.
abscission zone - ✔✔a wall of cells at the base of a petiole, that allows the
leaf to separate from the stem.
- two functions: leaf drop and to protect the region of the stem against
desiccation
acceptable risk - ✔✔the amount of risk that an owner is willing to accept
before tree failure.
acidic soil - ✔✔having a pH less than 7.0, in contrast with alkaline which
has a pH that is higher than 7.0.
,©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
actinomycetes - ✔✔microorganisms that have some characteristics of fungi
and bacteria. Soil actinomycetes are very tolerant of water stress and
contribute through their actions to that "good earth" aroma after a rain.
action threshold - ✔✔the point at which a pest requires the implementation
of a management tactic or control.
acute crotches - ✔✔stronger and wider than a co-dominant crotch, they are
not likely to be a branch that will fail in high winds and are considered
desirable.
adaptive growth - ✔✔an increase in wood production in localized areas on
a tree, in response to a decrease in wood strength or external loading to
maintain an even distribution of forces across the structure.
adsorption - ✔✔adhesion on contact of molecules to the surface of solids
or liquids with which they are in contact.
adventitious/epicormic growth - ✔✔new growth arising directly from
dormant or new buds on main branches, stems, or trunks often in response
to moisture and light that has no connection to apical meristems.
adventitious root: - ✔✔a root arising from parts of the root or the stem,
often in response to moisture and darkness that has no connection to
apical meristems.
,©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
aerial roots: - ✔✔roots that grow from stems toward the soil with the
capacity to become prop roots when they anchor in the soil.
aerobic microorganisms - ✔✔these microbes require free, gaseous oxygen
for growth.
aggregate: - ✔✔soil such as sand, silt, or clay, a cluster of soil particles and
organic matter, bonded together by exudates from microorganisms. It is
often used under paved surfaces, as backfill.
agroforestry or agro-sylviculture: - ✔✔is a land use management system in
which trees or shrubs are grown around or among crops or pastureland.
ait terrminal - ✔✔the uppermost point of a lightning protection system in a
tree. It is usually made of copper.
alkaline soil - ✔✔having a pH greater than 7.0, in contrast with acidic soil
which has a pH lower than 7.0.
alkaloids - ✔✔substances that are produced by trees and contain nitrogen
and are used by humans for medicines.
allelopathy - ✔✔the production of substances by one tree that adversely
affect other trees nearby. Root exudates from some trees can kill or stall
growth of many soil organisms.
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
amy;lase - ✔✔an enzyme that can change the starch chains back to
glucose molecules.
anerobic microorganism - ✔✔these microbes live in the absence of free
oxygen.
anon-eye nut - ✔✔drop-forged eye nut is used to fasten through-hardware
anchor(s), used when cabling trees. Advantage is the length of the rod can
be adjusted.
angiosperms - ✔✔hardwood trees that have covered seeds such as oaks
and maples. The seed is born within an ovary.
anions - ✔✔negatively charged atoms or molecules in fertilizer that become
available to the plant in water.
anther - ✔✔the pollen producing part of a flower.
anthocyanin - ✔✔a chemical that gives the red pigments to leaves and
other plant organs.
apical meristem - ✔✔meristems that increase the length of stems and
roots, and produce flowers.
apoplast (apoplasm) - ✔✔the framework of non-living cells and cell walls in
wood and bark. The apoplast stores bound water, which does not flow.
Arborist ISA Review Exam Questions
and Answers 100% Solved | Graded A+
abiotic - ✔✔pertaining to the nonliving parts of an ecosystem, such as soil
particles, bedrock, air, water.
abscisic acid (ABA) - ✔✔a plant hormone that stimulates stomatal closure
and promotes seed and bud dormancy.
abscission zone - ✔✔a wall of cells at the base of a petiole, that allows the
leaf to separate from the stem.
- two functions: leaf drop and to protect the region of the stem against
desiccation
acceptable risk - ✔✔the amount of risk that an owner is willing to accept
before tree failure.
acidic soil - ✔✔having a pH less than 7.0, in contrast with alkaline which
has a pH that is higher than 7.0.
,©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
actinomycetes - ✔✔microorganisms that have some characteristics of fungi
and bacteria. Soil actinomycetes are very tolerant of water stress and
contribute through their actions to that "good earth" aroma after a rain.
action threshold - ✔✔the point at which a pest requires the implementation
of a management tactic or control.
acute crotches - ✔✔stronger and wider than a co-dominant crotch, they are
not likely to be a branch that will fail in high winds and are considered
desirable.
adaptive growth - ✔✔an increase in wood production in localized areas on
a tree, in response to a decrease in wood strength or external loading to
maintain an even distribution of forces across the structure.
adsorption - ✔✔adhesion on contact of molecules to the surface of solids
or liquids with which they are in contact.
adventitious/epicormic growth - ✔✔new growth arising directly from
dormant or new buds on main branches, stems, or trunks often in response
to moisture and light that has no connection to apical meristems.
adventitious root: - ✔✔a root arising from parts of the root or the stem,
often in response to moisture and darkness that has no connection to
apical meristems.
,©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
aerial roots: - ✔✔roots that grow from stems toward the soil with the
capacity to become prop roots when they anchor in the soil.
aerobic microorganisms - ✔✔these microbes require free, gaseous oxygen
for growth.
aggregate: - ✔✔soil such as sand, silt, or clay, a cluster of soil particles and
organic matter, bonded together by exudates from microorganisms. It is
often used under paved surfaces, as backfill.
agroforestry or agro-sylviculture: - ✔✔is a land use management system in
which trees or shrubs are grown around or among crops or pastureland.
ait terrminal - ✔✔the uppermost point of a lightning protection system in a
tree. It is usually made of copper.
alkaline soil - ✔✔having a pH greater than 7.0, in contrast with acidic soil
which has a pH lower than 7.0.
alkaloids - ✔✔substances that are produced by trees and contain nitrogen
and are used by humans for medicines.
allelopathy - ✔✔the production of substances by one tree that adversely
affect other trees nearby. Root exudates from some trees can kill or stall
growth of many soil organisms.
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
amy;lase - ✔✔an enzyme that can change the starch chains back to
glucose molecules.
anerobic microorganism - ✔✔these microbes live in the absence of free
oxygen.
anon-eye nut - ✔✔drop-forged eye nut is used to fasten through-hardware
anchor(s), used when cabling trees. Advantage is the length of the rod can
be adjusted.
angiosperms - ✔✔hardwood trees that have covered seeds such as oaks
and maples. The seed is born within an ovary.
anions - ✔✔negatively charged atoms or molecules in fertilizer that become
available to the plant in water.
anther - ✔✔the pollen producing part of a flower.
anthocyanin - ✔✔a chemical that gives the red pigments to leaves and
other plant organs.
apical meristem - ✔✔meristems that increase the length of stems and
roots, and produce flowers.
apoplast (apoplasm) - ✔✔the framework of non-living cells and cell walls in
wood and bark. The apoplast stores bound water, which does not flow.
