ISA Exam (Arborist Certification)
Practice Questions# Part 1 With Correct
Answers 2026-2027 Update.
The ideal soil ratio for solids to pore space is:
(A) 20:80 (B) 35:65 (C) 40:60 (D) 50:50 - Answer D
What is the correct scientific name for the oak tree genus?
(A) Quercus (B) Pyrus (C) Larix (D) Acer - Answer A
Which of the following is not one of the five major categories of soil horizons?
(A) O (B) E (C) N (D) B - Answer C
Loam is least composed of what soil classification?
(A) Sand(B) Silt(C) Clay(D) Loam is composed of all soils evenly - Answer C
What is the difference in magnitude of acidity between a PH level reading of 4 vs. a PH reading
of 7?
(A) 1(B) 3(C) 100 (D) 1000 - Answer D
What is not a detrimental impact on tree growth from compaction?
(A) Restricted root growth
(B) Reduction of water availability
(C) Increasing organic material
(D) Restricting air movement - Answer C
Field capacity is achieved after the draining of which of the following?
(A) Gravitational water
(B) Capillary water
(C) Micropore water
(D) Compacted drainage - Answer A
What best defines the permanent wilting point soil moisture condition?
(A) Water is present in macro and micropores
(B) The condition present immediately after the removal of gravitational water
,(C) Water is held by soil but unavailable to plants such that they can't recover
(D) No water present in soil - Answer C
What soil below most likely has the lowest infiltration rate?
(A) Loose sand
(B) Compacted sand
(C) Loose clay
(D) Compacted clay - Answer D
What major soil horizon category is not included in the zone designated as topsoil?
(A) A (B) O (C) E (D) C - Answer D
What soil type is most easily compacted?
(A) Sand(B) Clay(C) Silt(D) Bedrock - Answer B
What is not a tree characteristic which helps to prevent the loss of water?
(A) Increased leaf surface area (B) Deep root systems(C) Leaf hairs(D) Waxy outer leaf layer -
Answer A
What irrigation system type provides water slowly to specific areas of the tree root zone?
(A) Drip irrigation(B) High-pressure injection (C) Basin irrigation
(D) Soaker hose - Answer A
Trees help to control stormwater runoff by all of the following means except:
(A) Trees hold water on bark and leaves
(B) Roots intercept and retain runoff
(C) Fallen leaves create a layer of absorption on the ground
(D) All of the above - Answer D
What is not an advantage of the use of mulching?
(A) Improve infiltration
(B) Promote deep root system
(C) Reduce soil evaporation
(D) Limit weed competition - Answer B
, What is the minimum slope for drainage pipes placed above an impervious layer?
(A) 1/16" per ft (B) 1/8" per ft (C) 1/4" per ft (D) 1/2" per ft - Answer C
The main function of a rain garden is which of the following?
(A) Collect and hold stormwater runoff
(B) Increase water infiltration
(C) Distribute runoff to dry areas
(D) Facilitate deep root systems - Answer A
What macronutrient most often has the largest requirement for the health of trees?
(A) Iron(B) Sulfur(C) Potassium (D) Nitrogen - Answer D
What essential element is more readily available in an acidic environment than alkaline?
(A) Iron(B) Calcium (C) Sulfur (D) Potassium - Answer A
Required fertilizer distribution rates for quick release are ______________ than for that of slow-
release.
(A) Greater(B) Less(C) Equal(D) No relationship - Answer B
What project factor listed below has a detrimental effect on the surface application of fertilizer?
(A) Constrained time(B) Inexperienced workers (C) Surface runoff(D) Shallow root structure -
Answer C
What element can be classified as a micronutrient?
(A) Magnesium (B) Calcium(C) Iron(D) Sulfur - Answer C
What method of fertilizer application may result in the development of thick patches of grass in
spots surrounding the tree?
(A) Liquid injection(B) Surface application (C) Foliar application (D) Implants - Answer A
What characteristic is used to differentiate between vascular plant classifications?
(A) Roots (B) Leaves (C) Seeds (D) Skin - Answer C
Of the options listed below which has the broadest level of taxonomic hierarchy?
(A) Genus (B) Order (C) Class (D) Family - Answer C
Practice Questions# Part 1 With Correct
Answers 2026-2027 Update.
The ideal soil ratio for solids to pore space is:
(A) 20:80 (B) 35:65 (C) 40:60 (D) 50:50 - Answer D
What is the correct scientific name for the oak tree genus?
(A) Quercus (B) Pyrus (C) Larix (D) Acer - Answer A
Which of the following is not one of the five major categories of soil horizons?
(A) O (B) E (C) N (D) B - Answer C
Loam is least composed of what soil classification?
(A) Sand(B) Silt(C) Clay(D) Loam is composed of all soils evenly - Answer C
What is the difference in magnitude of acidity between a PH level reading of 4 vs. a PH reading
of 7?
(A) 1(B) 3(C) 100 (D) 1000 - Answer D
What is not a detrimental impact on tree growth from compaction?
(A) Restricted root growth
(B) Reduction of water availability
(C) Increasing organic material
(D) Restricting air movement - Answer C
Field capacity is achieved after the draining of which of the following?
(A) Gravitational water
(B) Capillary water
(C) Micropore water
(D) Compacted drainage - Answer A
What best defines the permanent wilting point soil moisture condition?
(A) Water is present in macro and micropores
(B) The condition present immediately after the removal of gravitational water
,(C) Water is held by soil but unavailable to plants such that they can't recover
(D) No water present in soil - Answer C
What soil below most likely has the lowest infiltration rate?
(A) Loose sand
(B) Compacted sand
(C) Loose clay
(D) Compacted clay - Answer D
What major soil horizon category is not included in the zone designated as topsoil?
(A) A (B) O (C) E (D) C - Answer D
What soil type is most easily compacted?
(A) Sand(B) Clay(C) Silt(D) Bedrock - Answer B
What is not a tree characteristic which helps to prevent the loss of water?
(A) Increased leaf surface area (B) Deep root systems(C) Leaf hairs(D) Waxy outer leaf layer -
Answer A
What irrigation system type provides water slowly to specific areas of the tree root zone?
(A) Drip irrigation(B) High-pressure injection (C) Basin irrigation
(D) Soaker hose - Answer A
Trees help to control stormwater runoff by all of the following means except:
(A) Trees hold water on bark and leaves
(B) Roots intercept and retain runoff
(C) Fallen leaves create a layer of absorption on the ground
(D) All of the above - Answer D
What is not an advantage of the use of mulching?
(A) Improve infiltration
(B) Promote deep root system
(C) Reduce soil evaporation
(D) Limit weed competition - Answer B
, What is the minimum slope for drainage pipes placed above an impervious layer?
(A) 1/16" per ft (B) 1/8" per ft (C) 1/4" per ft (D) 1/2" per ft - Answer C
The main function of a rain garden is which of the following?
(A) Collect and hold stormwater runoff
(B) Increase water infiltration
(C) Distribute runoff to dry areas
(D) Facilitate deep root systems - Answer A
What macronutrient most often has the largest requirement for the health of trees?
(A) Iron(B) Sulfur(C) Potassium (D) Nitrogen - Answer D
What essential element is more readily available in an acidic environment than alkaline?
(A) Iron(B) Calcium (C) Sulfur (D) Potassium - Answer A
Required fertilizer distribution rates for quick release are ______________ than for that of slow-
release.
(A) Greater(B) Less(C) Equal(D) No relationship - Answer B
What project factor listed below has a detrimental effect on the surface application of fertilizer?
(A) Constrained time(B) Inexperienced workers (C) Surface runoff(D) Shallow root structure -
Answer C
What element can be classified as a micronutrient?
(A) Magnesium (B) Calcium(C) Iron(D) Sulfur - Answer C
What method of fertilizer application may result in the development of thick patches of grass in
spots surrounding the tree?
(A) Liquid injection(B) Surface application (C) Foliar application (D) Implants - Answer A
What characteristic is used to differentiate between vascular plant classifications?
(A) Roots (B) Leaves (C) Seeds (D) Skin - Answer C
Of the options listed below which has the broadest level of taxonomic hierarchy?
(A) Genus (B) Order (C) Class (D) Family - Answer C
