ISA Certified Arborist : Chapter 1 - Tree Biology
Exam Questions And Correct Answers 2025-
2026 | Get It Correct !!!
Abscission Zone -
-Correct Answers
Area at the base of a petiole, small branch, or flower
where cellular breakdown leads to leaf, flower, or fruit
drop.
Absorbing Roots -
-Correct Answers
Fine roots with functional root hairs that are responsible
for the uptake of water and minerals.
Adventitious Bud -
-Correct Answers
Bud arising peripherally from a place other than a leaf
axil or shoot tip, usually as a result of hormonal triggers.
Aerial Roots -
-Correct Answers
Above ground roots. Usually adventitious in nature and
sometimes having unique adaptive functions.
Angiosperm -
-Correct Answers
Plant with seeds borne in an ovary. Consists of two large
groups; monocotyledons (grasses, palms, and related
plants) and dicotyledons (most woody trees, shrubs,
herbaceous plants, and related plants).
1
,Anthocyanin -
-Correct Answers
Red or purple pigment responsible for those colors in
some parts of plants.
Apical Bud -
-Correct Answers
Bud at the tip of a twig or shoot.
Apical Dominance -
-Correct Answers
Condition in which the terminal bud inhibits the growth
and development of the lateral buds on the same stem
formed during the same season.
Apical Meristem -
-Correct Answers
Growing point in buds and at the tips of the shoots.
Auxins -
-Correct Answers
Plant hormones that promote or regulate the growth
and development of plants. Produced at sites where
cells are dividing, primarily in the shoot tips. Auxin-like
compounds may be synthetically produced.
Axial Transport -
-Correct Answers
Movement of water, minerals, or photosynthates
longitudinally within a tree.
2
, Axillary Bud -
-Correct Answers
Bud in the axil of a leaf. Lateral bud.
Barrier Zone -
-Correct Answers
Chemical and anatomical barrier formed by the
cambium in response to wounding. Inhibits the spread
of decay into xylem tissue formed after the time of
wounding. Wall 4 in the CODIT model.
Branch Bark Ridge -
-Correct Answers
Raised strip of bark at the top of a branch union, where
the growth and expansion of the trunk or parent stem
and adjoining branch push the bark into a ridge.
Branch Collar -
-Correct Answers
Swollen area where a branch meets the trunk or
another branch that is created by the overlapping
vascular tissues from both the branch and the trunk.
Branch Union -
-Correct Answers
Point where a branch originates from the trunk or
another branch.
Bud -
-Correct Answers
3
Exam Questions And Correct Answers 2025-
2026 | Get It Correct !!!
Abscission Zone -
-Correct Answers
Area at the base of a petiole, small branch, or flower
where cellular breakdown leads to leaf, flower, or fruit
drop.
Absorbing Roots -
-Correct Answers
Fine roots with functional root hairs that are responsible
for the uptake of water and minerals.
Adventitious Bud -
-Correct Answers
Bud arising peripherally from a place other than a leaf
axil or shoot tip, usually as a result of hormonal triggers.
Aerial Roots -
-Correct Answers
Above ground roots. Usually adventitious in nature and
sometimes having unique adaptive functions.
Angiosperm -
-Correct Answers
Plant with seeds borne in an ovary. Consists of two large
groups; monocotyledons (grasses, palms, and related
plants) and dicotyledons (most woody trees, shrubs,
herbaceous plants, and related plants).
1
,Anthocyanin -
-Correct Answers
Red or purple pigment responsible for those colors in
some parts of plants.
Apical Bud -
-Correct Answers
Bud at the tip of a twig or shoot.
Apical Dominance -
-Correct Answers
Condition in which the terminal bud inhibits the growth
and development of the lateral buds on the same stem
formed during the same season.
Apical Meristem -
-Correct Answers
Growing point in buds and at the tips of the shoots.
Auxins -
-Correct Answers
Plant hormones that promote or regulate the growth
and development of plants. Produced at sites where
cells are dividing, primarily in the shoot tips. Auxin-like
compounds may be synthetically produced.
Axial Transport -
-Correct Answers
Movement of water, minerals, or photosynthates
longitudinally within a tree.
2
, Axillary Bud -
-Correct Answers
Bud in the axil of a leaf. Lateral bud.
Barrier Zone -
-Correct Answers
Chemical and anatomical barrier formed by the
cambium in response to wounding. Inhibits the spread
of decay into xylem tissue formed after the time of
wounding. Wall 4 in the CODIT model.
Branch Bark Ridge -
-Correct Answers
Raised strip of bark at the top of a branch union, where
the growth and expansion of the trunk or parent stem
and adjoining branch push the bark into a ridge.
Branch Collar -
-Correct Answers
Swollen area where a branch meets the trunk or
another branch that is created by the overlapping
vascular tissues from both the branch and the trunk.
Branch Union -
-Correct Answers
Point where a branch originates from the trunk or
another branch.
Bud -
-Correct Answers
3
