ISA ARBORIST CERTIFICATION
PRACTICE EXAM QUESTIONS
AND CORRECT ANSWERS
LATEST UPDATE 2026/2027
GRADED A+ .
1. The ideal soil ratio for solids to pore space is:
(A) 20: 80 (B) 35: 65 (C) 40: 60 (D) 50: 50✔✔ correct answ D
2. What is the correct scientific name for the oak tree genus?
(A) Quercus (B) Pyrus (C) Larix (D) Acer✔✔ correct answ A
3. Which of the following is not one of the five major categories of soil hori-zons?
(A) O (B) E (C) N (D) B✔✔ correct answ C
4. Loam is least composed of what soil classification?
(A) Sand(B) Silt(C) Clay(D) Loam is composed of all soils evenly✔✔ correct answ C
5. 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✔✔ correct answ D
6. 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✔✔ correct answ C
7. Field capacity is achieved after the draining of which of the following?
(A) Gravitational water
(B) Capillary water
(C) Micropore water
(D) Compacted drainage✔✔ correct answ A
8. 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✔✔ correct answ C
9. What soil below most likely has the lowest infiltration rate?
(A) Loose sand
(B) Compacted sand
(C) Loose clay
(D) Compacted clay✔✔ correct answ D
10. What major soil horizon category is not included in the zone designated as topsoil?
(A) A (B) O (C) E (D) C✔✔ correct answ D
11. What soil type is most easily compacted?
(A) Sand(B) Clay(C) Silt(D) Bedrock✔✔ correct answ B
12. 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✔✔ correct answ A
13. 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✔✔ correct answ A
,14. Trees help to control stormwater runoff by all of the following means except✔✔ correct answ
(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✔✔ correct answ D
15. 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✔✔ correct answ B
16. 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✔✔ correct answ C
17. 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✔✔ correct answ A
, 18. What macronutrient most often has the largest requirement for the health of trees?
(A) Iron(B) Sulfur(C) Potassium (D) Nitrogen✔✔ correct answ D
19. What essential element is more readily available in an acidic environment than alkaline?
(A) Iron(B) Calcium (C) Sulfur (D) Potassium✔✔ correct answ A
20. Required fertilizer distribution rates for quick release are than
for that of slow-release.
(A) Greater(B) Less(C) Equal(D) No relationship✔✔ correct answ B
21. 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✔✔ correct answ C
22. What element can be classified as a micronutrient?
(A) Magnesium (B) Calcium(C) Iron(D) Sulfur✔✔ correct answ C
23. 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✔✔ correct answ A
24. What characteristic is used to differentiate between vascular plant classifi-cations?
(A) Roots (B) Leaves (C) Seeds (D) Skin✔✔ correct answ C
25. Of the options listed below which has the broadest level of taxonomic hierarchy?
(A) Genus (B) Order (C) Class (D) Family✔✔ correct answ C
26. What characteristic below is used to differentiate between a simple leaf and a compound leaf?
(A) Number of buds (B) Length of petiole (C) Shape of leaflet (D) Number of leaflets✔✔ correct answ D
27. What major group of conifers is defined by needles borne in clusters?
(A) Pine (B) Spruce (C) Fir(D) Juniper✔✔ correct answ A
28. What leaf margin type is characterized by having a smooth edge?
(A) Entire (B) Serrate (C) Serrulate (D) Dentate✔✔ correct answ A
PRACTICE EXAM QUESTIONS
AND CORRECT ANSWERS
LATEST UPDATE 2026/2027
GRADED A+ .
1. The ideal soil ratio for solids to pore space is:
(A) 20: 80 (B) 35: 65 (C) 40: 60 (D) 50: 50✔✔ correct answ D
2. What is the correct scientific name for the oak tree genus?
(A) Quercus (B) Pyrus (C) Larix (D) Acer✔✔ correct answ A
3. Which of the following is not one of the five major categories of soil hori-zons?
(A) O (B) E (C) N (D) B✔✔ correct answ C
4. Loam is least composed of what soil classification?
(A) Sand(B) Silt(C) Clay(D) Loam is composed of all soils evenly✔✔ correct answ C
5. 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✔✔ correct answ D
6. 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✔✔ correct answ C
7. Field capacity is achieved after the draining of which of the following?
(A) Gravitational water
(B) Capillary water
(C) Micropore water
(D) Compacted drainage✔✔ correct answ A
8. 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✔✔ correct answ C
9. What soil below most likely has the lowest infiltration rate?
(A) Loose sand
(B) Compacted sand
(C) Loose clay
(D) Compacted clay✔✔ correct answ D
10. What major soil horizon category is not included in the zone designated as topsoil?
(A) A (B) O (C) E (D) C✔✔ correct answ D
11. What soil type is most easily compacted?
(A) Sand(B) Clay(C) Silt(D) Bedrock✔✔ correct answ B
12. 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✔✔ correct answ A
13. 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✔✔ correct answ A
,14. Trees help to control stormwater runoff by all of the following means except✔✔ correct answ
(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✔✔ correct answ D
15. 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✔✔ correct answ B
16. 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✔✔ correct answ C
17. 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✔✔ correct answ A
, 18. What macronutrient most often has the largest requirement for the health of trees?
(A) Iron(B) Sulfur(C) Potassium (D) Nitrogen✔✔ correct answ D
19. What essential element is more readily available in an acidic environment than alkaline?
(A) Iron(B) Calcium (C) Sulfur (D) Potassium✔✔ correct answ A
20. Required fertilizer distribution rates for quick release are than
for that of slow-release.
(A) Greater(B) Less(C) Equal(D) No relationship✔✔ correct answ B
21. 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✔✔ correct answ C
22. What element can be classified as a micronutrient?
(A) Magnesium (B) Calcium(C) Iron(D) Sulfur✔✔ correct answ C
23. 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✔✔ correct answ A
24. What characteristic is used to differentiate between vascular plant classifi-cations?
(A) Roots (B) Leaves (C) Seeds (D) Skin✔✔ correct answ C
25. Of the options listed below which has the broadest level of taxonomic hierarchy?
(A) Genus (B) Order (C) Class (D) Family✔✔ correct answ C
26. What characteristic below is used to differentiate between a simple leaf and a compound leaf?
(A) Number of buds (B) Length of petiole (C) Shape of leaflet (D) Number of leaflets✔✔ correct answ D
27. What major group of conifers is defined by needles borne in clusters?
(A) Pine (B) Spruce (C) Fir(D) Juniper✔✔ correct answ A
28. What leaf margin type is characterized by having a smooth edge?
(A) Entire (B) Serrate (C) Serrulate (D) Dentate✔✔ correct answ A
