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ISA BCMA practice questions

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Question 1Tree Biology

Which pigment primarily captures light energy for photosynthesis in tree leaves?

  1. Lignin
  2. Anthocyanin
  3. Chlorophyll Correct answer.
  4. Suberin

Explanation

Chlorophyll absorbs mainly red and blue wavelengths and drives the light reactions of photosynthesis. Accessory pigments pass energy to chlorophyll but do not replace it as the main light-capturing pigment.

Question 2Tree Biology

Through which structures does most water vapor escape from a broadleaf tree's foliage?

  1. Lenticels
  2. Stomata Correct answer.
  3. Hydathodes
  4. The cuticle

Explanation

Stomata are epidermal pores bounded by guard cells and are the main route for both water loss and carbon dioxide uptake. The cuticle restricts water loss but also resists gas exchange.

Question 3Tree Biology

Sugars made in a tree's leaves are transported to the roots mainly through which tissue?

  1. Phloem Correct answer.
  2. Xylem
  3. Pith
  4. Periderm

Explanation

Phloem sieve elements carry sugars from sources such as leaves to sinks such as roots, fruits and growing shoots. Xylem conducts water and dissolved minerals upward rather than sugars downward.

Question 4Tree Biology

The vascular cambium adds which tissues as a woody stem grows in girth?

  1. Pith and cortex parenchyma
  2. Xylem inward, phloem outward Correct answer.
  3. Cork and cork cambium
  4. Primary xylem and primary phloem

Explanation

The vascular cambium is a lateral meristem that produces secondary xylem toward the inside of the stem and secondary phloem toward the outside. This bidirectional division is what thickens woody stems and roots.

Question 5Tree Biology

What is the primary function of root hairs?

  1. Increases surface area for uptake Correct answer.
  2. Stores starch through the winter
  3. Carries sugars down to the roots
  4. Anchors the tree in the soil

Explanation

Root hairs are thin extensions of epidermal cells just behind the root tip that expand absorptive surface area for water and mineral uptake. Anchoring, storage and sugar transport are functions of other tissues.

Question 6Tree Biology

Apical dominance in a tree shoot refers to which phenomenon?

  1. The tendency of roots to grow downward
  2. Seasonal shedding of leaves in autumn
  3. Suppression of lateral buds by the apex Correct answer.
  4. Wood formed on the lower side of a lean

Explanation

Auxin moving basipetally from the terminal bud inhibits outgrowth of lateral buds below it, so the shoot extends mainly in length. Removing or pruning the terminal bud releases lateral buds from this suppression.

Question 7Tree Biology

In the CODIT model of compartmentalization, which boundary forms first after wounding?

  1. Wall 2, the annual ring boundary
  2. Wall 4, the new barrier zone
  3. Wall 3, ray parenchyma
  4. Wall 1, plugging of vessels Correct answer.

Explanation

Wall 1 forms quickly when existing vessels are plugged above and below the wound, restricting vertical spread of decay. The remaining walls form more slowly and in sequence as the tree responds.

Question 8Tree Biology

In a leaning conifer stem, on which side does compression wood develop?

  1. Side facing the prevailing wind
  2. Evenly around the stem
  3. Upper side of the lean
  4. Lower side of the lean Correct answer.

Explanation

Compression wood forms on the lower side of a leaning conifer stem and pushes the stem back toward vertical. Deciduous trees instead form tension wood on the upper side of the lean.

Question 9Tree Biology

What best describes the fungal partner in an ectomycorrhizal association with a tree?

  1. Grow only inside leaf tissue
  2. Form a mantle around root tips Correct answer.
  3. Penetrate root cells and fix nitrogen
  4. Cause root rot in healthy trees

Explanation

Ectomycorrhizal fungi sheath short roots with a mantle and send hyphae into the surrounding soil, improving uptake of phosphorus, other nutrients and water. They do not fix nitrogen and generally do not invade root cells.

Question 10Tree Biology

Compared with sapwood, heartwood is typically which of the following?

  1. More permeable to water
  2. Rich in living parenchyma
  3. The main pathway for water conduction
  4. Darker and less permeable Correct answer.

Explanation

As sapwood ages, parenchyma dies and extractives are deposited, producing darker, less permeable heartwood that no longer conducts water. Sapwood remains the functional conductive wood.

Question 11Tree Biology

An embolism forms in xylem most often when which condition occurs?

  1. Stomata open widely at midday
  2. Xylem tension draws in air Correct answer.
  3. Phloem pressure rises sharply
  4. Root pressure pushes water upward

Explanation

Under strong water stress, xylem tension can pull air through a pit membrane into a conduit, breaking the water column. The resulting embolism blocks flow and lowers the stem's hydraulic conductance.

Question 12Tree Biology

Where does a deciduous tree mainly hold its carbohydrate reserves through winter?

  1. In living parenchyma of roots and stems Correct answer.
  2. In the fallen leaves on the forest floor
  3. In the heartwood at the stem center
  4. In the dead outer layers of bark

Explanation

Sugar is moved into parenchyma of roots, trunk and branches and stored as starch, then mobilized to support spring growth before leaves expand. Dead tissues such as heartwood and outer bark are not storage sites.

Question 13Tree Biology

Ethylene is chiefly responsible for which set of tree responses?

  1. Cell division in the cambium
  2. Fruit ripening and leaf abscission Correct answer.
  3. Gravitropic bending of roots
  4. Phototropic bending of growing shoots

Explanation

Ethylene is a gaseous hormone that promotes ripening, senescence and formation of the abscission zone that lets leaves drop. Tropic bending and cambial growth are governed mainly by auxin and other growth regulators.

Question 14Tree Biology

In a temperate tree's annual ring, which wood forms first in spring?

  1. Latewood with thick cell walls
  2. The pith at the stem center
  3. The cork cambium
  4. Earlywood with wide vessels Correct answer.

Explanation

Earlywood forms first when soil water and growth are plentiful, so conduits are wide and walls thin. Latewood follows later in the season with narrower, thicker-walled cells.

Question 15Tree Biology

Which mechanism lifts water to the crown of a tall tree?

  1. Active pumping by xylem parenchyma
  2. Root pressure alone
  3. Phloem loading at the leaves
  4. Cohesion-tension from transpiration Correct answer.

Explanation

Transpiration creates negative pressure at the leaves that pulls a continuous water column upward, held together by cohesion and adhesion. Root pressure is far too weak to raise water to great heights.

Question 16Tree Biology

Actinorhizal trees such as alder obtain nitrogen through root nodules formed with which organism?

  1. Rhizobium bacteria
  2. Mycorrhizal fungi
  3. Agrobacterium
  4. Frankia Correct answer.

Explanation

Frankia is an actinomycete that forms nitrogen-fixing nodules on roots of actinorhizal trees including alder and Casuarina. Rhizobium nodulates legumes, and mycorrhizal fungi aid nutrient uptake rather than nitrogen fixation.

Question 17Tree Biology

According to the hydraulic safety-efficiency trade-off, xylem conduits with large diameters tend to do which of the following?

  1. Have thicker walls than tracheids
  2. Occur mainly in gymnosperm wood
  3. Conduct efficiently but cavitate readily Correct answer.
  4. Conduct water slowly, resisting freezing

Explanation

Flow through a conduit scales steeply with diameter, so wide vessels are hydraulically efficient. Their large pit membranes, however, fail under high tension, making them more vulnerable to cavitation.

Question 18Tree Biology

Auxin produced in a shoot apex moves through the stem in which manner?

  1. Radially, through xylem rays
  2. Basipetally, in a polar manner Correct answer.
  3. Acropetally, within the phloem
  4. Bidirectionally, within sieve tubes

Explanation

Auxin is transported cell to cell from the shoot tip toward the base in a polar, basipetal direction, which is how it maintains apical dominance. This polar transport is separate from the mass flow in phloem sieve tubes.

Question 19Tree Biology

Tyloses form in a hardwood vessel when which event takes place?

  1. Fungal hyphae colonize the tracheids
  2. Cambial cells divide to form new phloem
  3. Ray cells die and leave air-filled spaces
  4. Parenchyma expands into vessel lumens Correct answer.

Explanation

Tyloses are balloon-like outgrowths of living parenchyma that push through pits into vessel lumens and block them. They are a common defense after wounding and in the transition to heartwood in hardwoods.

Question 20Tree Biology

Which anatomical feature reliably distinguishes hardwood from softwood?

  1. Presence of vessels Correct answer.
  2. Presence of tracheids
  3. Presence of rays
  4. Presence of annual rings

Explanation

Hardwoods are angiosperms and have vessel elements in addition to other cell types, while softwoods are conifers whose water conduction relies on tracheids alone. Tracheids, rays and growth rings occur in both groups.

Question 21Tree Identification and Selection

A twig bears two leaves at the same node, one on each side of the stem. Which leaf arrangement is this?

  1. Whorled
  2. Fascicled
  3. Opposite Correct answer.
  4. Alternate

Explanation

Leaf arrangement is defined by how many leaves arise at each node and how they are positioned. Opposite arrangement means two leaves attach at the same node on opposite sides of the stem, as in maples and ashes.

Question 22Tree Identification and Selection

Which description fits a pinnately compound leaf?

  1. Leaflets arranged along a central rachis Correct answer.
  2. A single blade with a lobed margin
  3. Leaflets all arising from one point
  4. A needle-like blade attached singly to the twig

Explanation

In a pinnately compound leaf, leaflets are attached along both sides of a central axis called the rachis. Palmate leaves have leaflets arising from a single point, and simple leaves have one undivided blade.

Question 23Tree Identification and Selection

Eastern white pine (Pinus strobus) is identified in part by the number of needles in each fascicle. How many needles per fascicle does it typically have?

  1. One
  2. Two
  3. Three
  4. Five Correct answer.

Explanation

White pine needles are borne in bundles called fascicles, typically five per bundle. Fascicle count is a reliable field character because related pines differ consistently, such as red pine with two and pitch pine with three.

Question 24Tree Identification and Selection

Parallel venation in leaves is typical of which group?

  1. Conifers
  2. Monocots Correct answer.
  3. Dicotyledonous trees
  4. Ferns

Explanation

Monocots, such as palms and grasses, generally have leaves with veins running parallel to one another. Dicots have netted or branching venation, which is the pattern seen in most broadleaf trees.

Question 25Tree Identification and Selection

A tree rated hardy to USDA zone 5 is expected to survive minimum winter temperatures near which value?

  1. -23°C (-10°F)
  2. -34°C (-30°F)
  3. -29°C (-20°F) Correct answer.
  4. -18°C (0°F)

Explanation

USDA hardiness zones are based on average annual minimum temperature, with each zone spanning about 5.6°C (10°F). Zone 5 corresponds to a minimum of about -29°C (-20°F).

Question 26Tree Identification and Selection

Which statement correctly describes a gymnosperm such as a pine?

  1. It has broad, flat deciduous leaves
  2. Seeds are exposed on cone scales Correct answer.
  3. It bears fruit that encloses its seeds
  4. It produces true flowers with petals

Explanation

Gymnosperm means "naked seed": ovules and seeds are borne exposed on the scales of cones rather than enclosed in an ovary. Angiosperms, by contrast, enclose their seeds within fruit.

Question 27Tree Identification and Selection

Buds whose scales overlap like roof shingles, with the edges of individual scales visible, are described as:

  1. Accessory
  2. Imbricate Correct answer.
  3. Naked
  4. Valvate

Explanation

Imbricate buds have overlapping scales, each with a visible margin, which is the most common bud type in temperate trees. Valvate buds have scales meeting edge to edge without overlapping, and naked buds lack scales entirely.

Question 28Tree Identification and Selection

The small dots or short lines visible inside a leaf scar on a dormant twig are called:

  1. Lenticels
  2. Bundle scars Correct answer.
  3. Bud scales
  4. Stipules

Explanation

Bundle scars mark the points where vascular bundles passed from the stem into the petiole. Their number and arrangement are useful identification characters, such as three in walnut and many in sumac.

Question 29Tree Identification and Selection

A dichotomous key offers the couplet "leaves needle-like" versus "leaves broad and flat." A specimen has flattened needles in two ranks. Which action is most appropriate?

  1. Stop, because flattened needles are not needles
  2. Reject the specimen as unidentifiable
  3. Record the tree as a broadleaf evergreen
  4. Follow the needle-like lead in the key Correct answer.

Explanation

A key is used by matching the specimen to the description that fits best at each couplet. Flattened needles, such as those of hemlock or yew, are still needle-like rather than broad and flat.

Question 30Tree Identification and Selection

A tree will be planted in a lawn directly beneath an overhead electric line. Which selection criterion matters most?

  1. Fast growth rate
  2. Mature size Correct answer.
  3. Fall leaf color
  4. Spring flower color

Explanation

Matching a tree's ultimate size to the available space is the core of "right tree, right place." A tree whose mature height and spread fit under the line will require far less corrective pruning and cause fewer conflicts.

Question 31Tree Identification and Selection

In the name Acer rubrum 'October Glory', what does the portion in single quotes identify?

  1. Cultivar Correct answer.
  2. Species epithet
  3. Genus
  4. Family

Explanation

Single quotes around a name following the species denote a cultivated variety, or cultivar. The genus is the first word and the species epithet is the second, so the quoted name identifies a selected horticultural form.

Question 32Tree Identification and Selection

A pin oak growing in strongly alkaline soil commonly shows interveinal chlorosis because:

  1. Iron is less available for uptake Correct answer.
  2. Nitrogen is leached from the soil
  3. Too much phosphorus is present
  4. The tree is receiving too much water

Explanation

At high soil pH, iron becomes chemically unavailable even when it is present in the soil, producing yellowing between green veins. Acid-loving species such as pin oak are especially prone to this disorder.

Question 33Tree Identification and Selection

For a street planting along a road that receives heavy winter deicing salt, which trait should be given the highest priority?

  1. Deep taproot
  2. Salt tolerance Correct answer.
  3. Fast growth rate
  4. Attractive fruit display

Explanation

Deicing salt accumulates in soil and in spray, damaging sensitive trees over time. Choosing a species rated salt-tolerant is the most direct way to reduce decline at such a site.

Question 34Tree Identification and Selection

Which is the strongest reason to favor a native species over an exotic one for a naturalized site?

  1. They grow faster than non-native trees
  2. They never require irrigation or pruning
  3. They are immune to introduced pests
  4. They suit local climate and soils Correct answer.

Explanation

Native species are adapted to the local climate, soils, and associated organisms, which usually improves establishment and reduces long-term maintenance. No tree is maintenance-free or fully immune to pests.

Question 35Tree Identification and Selection

A tree that maintains a single dominant central leader and a pyramidal crown is described as having which form?

  1. Vase
  2. Excurrent Correct answer.
  3. Decurrent
  4. Columnar

Explanation

Excurrent form means the central leader remains dominant, producing a conical or pyramidal crown, as in many conifers and some shade trees. Decurrent form is spreading, with no single dominant leader.

Question 36Tree Identification and Selection

Which step best reduces the chance of planting an invasive tree species?

  1. Planting only trees with showy flowers
  2. Choosing the least expensive cultivar
  3. Selecting the largest available specimen
  4. Checking regional invasive species lists Correct answer.

Explanation

Invasive status varies by region and climate, so local noxious-weed or invasive-plant lists are the most reliable screening tool before selection. A species that is benign in one region may be problematic in another.

Question 37Tree Identification and Selection

A twig has a chambered pith and leaf scars containing three bundle scars. Which genus is most likely?

  1. Acer
  2. Fraxinus
  3. Juglans Correct answer.
  4. Platanus

Explanation

Walnut (Juglans) twigs are characterized by a chambered pith and large leaf scars with three bundle scars. Acer and Fraxinus have opposite arrangement, and Platanus has leaf bases that encircle the bud.

Question 38Tree Identification and Selection

A city needs a large shade tree for a site where emerald ash borer is established and Dutch elm disease is present. Which choice best avoids both problems?

  1. Ulmus americana
  2. Fraxinus pennsylvanica
  3. Gleditsia triacanthos Correct answer.
  4. Fraxinus americana

Explanation

Honeylocust is not a host for emerald ash borer or the Dutch elm disease pathogen, so it avoids both risks. Ash species are killed by emerald ash borer, and American elm is highly susceptible to Dutch elm disease.

Question 39Tree Identification and Selection

Which common landscape tree is dioecious, with pollen cones and seed-bearing structures on separate trees?

  1. Quercus alba
  2. Ginkgo biloba Correct answer.
  3. Liquidambar styraciflua
  4. Platanus occidentalis

Explanation

Ginkgo is dioecious, so male and female cones are borne on different trees, which is why male cultivars are specified where the fleshy, odorous seeds would be a problem. The other species are monoecious, bearing both flower types on the same tree.

Question 40Tree Identification and Selection

Which species is best suited to a hot, dry site with compacted, alkaline soil in full sun?

  1. River birch
  2. Silver maple
  3. Black willow
  4. Honeylocust Correct answer.

Explanation

Honeylocust tolerates drought, compacted soil, and high pH, making it a dependable choice for harsh urban sites. The other species are bottomland trees that prefer moist, usually acidic soils.

Question 41Soil Management

Which sequence lists soil particles in order from smallest to largest diameter?

  1. Sand, silt, clay
  2. Silt, clay, sand
  3. Clay, sand, silt
  4. Clay, silt, sand Correct answer.

Explanation

Soil separates are defined by particle diameter: clay is less than 0.002 mm, silt is 0.002 to 0.05 mm, and sand is 0.05 to 2.0 mm. Therefore the correct order from smallest to largest is clay, silt, sand.

Question 42Soil Management

Which soil separate has the greatest total water-holding capacity?

  1. Gravel
  2. Silt
  3. Clay Correct answer.
  4. Sand

Explanation

Clay particles have the greatest specific surface area and the finest pore network, so a clay soil retains the most total water. Much of that water may be held too tightly for plant uptake, but total water-holding capacity is highest in clay.

Question 43Soil Management

Approximately what proportion of the volume of a well-structured loam soil is pore space?

  1. 50% Correct answer.
  2. 10%
  3. 75%
  4. 25%

Explanation

A well-structured mineral soil is roughly half solids and half pore space. About 50% pore space provides a balance of air-filled macropores and water-filled micropores.

Question 44Soil Management

Cation exchange capacity is best defined as the soil's capacity to:

  1. retain anions such as nitrate
  2. conduct water through macropores
  3. neutralize soil acidity permanently
  4. hold and exchange positively charged ions Correct answer.

Explanation

Cation exchange capacity is the sum of exchangeable cations such as calcium, magnesium, potassium, and hydrogen held on negatively charged surfaces of clay and organic matter. It is measured in cmol(+)/kg or meq/100 g.

Question 45Soil Management

In which soil pH range are most plant nutrients generally most available?

  1. 4.0 to 5.0
  2. 5.0 to 6.0
  3. 6.0 to 7.0 Correct answer.
  4. 7.5 to 8.5

Explanation

Most essential nutrients reach their greatest overall availability at a soil pH of about 6.0 to 7.0. At lower pH, aluminum and manganese can become toxic and phosphorus is fixed; at higher pH, iron, manganese, zinc, and phosphorus become less available.

Question 46Soil Management

What is the primary benefit of maintaining an organic mulch ring over a tree's root zone?

  1. It eliminates any need for mechanical soil aeration
  2. It increases soil bulk density around the root zone
  3. It raises soil pH to reduce iron chlorosis
  4. It buffers temperature and conserves moisture Correct answer.

Explanation

Organic mulch insulates the soil surface, reducing temperature extremes and evaporation, and it improves soil structure as it decomposes. It does not replace aeration or eliminate irrigation needs.

Question 47Soil Management

A soil test shows bulk density of 1.65 g/cm3 in a clay loam beneath a heavily trafficked lawn, compared with 1.25 g/cm3 in an adjacent bed. What does this most likely indicate?

  1. Increased cation exchange capacity
  2. Compaction with reduced macropores Correct answer.
  3. Higher organic matter content
  4. Improved aggregation and pore space

Explanation

Bulk density is the mass of dry soil per unit volume. Compaction squeezes particles together, reducing pore space and increasing bulk density, so a reading of 1.65 versus 1.25 g/cm3 indicates compaction.

Question 48Soil Management

In a sandy soil with low clay content, which fraction contributes most to cation exchange capacity?

  1. Silt particles
  2. Sand particles
  3. Iron oxides
  4. Organic matter Correct answer.

Explanation

Sand and silt have little surface charge, so their cation exchange capacity is low. Organic matter has a high cation exchange capacity per unit mass and is usually the dominant exchange surface in sandy soils.

Question 49Soil Management

Which material is applied to lower soil pH?

  1. Dolomitic lime
  2. Wood ash
  3. Elemental sulfur Correct answer.
  4. Ground limestone

Explanation

Elemental sulfur is oxidized by soil microorganisms to sulfuric acid, which lowers pH. Limestone and dolomitic lime raise pH, and wood ash is alkaline.

Question 50Soil Management

Which symptom is most typical of iron deficiency in a tree growing on high-pH soil?

  1. Purple discoloration of stems
  2. Wilting from root rot
  3. Interveinal chlorosis on young leaves Correct answer.
  4. Marginal necrosis on older leaves

Explanation

Iron is relatively immobile in plants, so deficiency appears first on new growth as interveinal yellowing with green veins. High soil pH reduces iron availability even when iron is present in the soil.