ICAR AICE-JRF/SRF (PhD) — Subject 59 Forestry · India · National Testing Agency for ICAR
Original practice questions written to the published syllabus · not past papersThe structure of wood and how it determines strength, density, durability and use: macroscopic and microscopic identification of timbers and their physical and mechanical properties.
In the exams: ICAR AICE-JRF 59 Unit 7 (wood anatomy); IFoS Forestry Paper II Section B (forest resources and utilization); PRC Forest Engineering and Utilization
ICAR AICE-JRF/SRF (PhD) — Forestry, Unit 7
MCQs on wood anatomy (softwood and hardwood structure, cell wall), wood properties and their relation to utilisation.
How our questions for ICAR AICE-JRF/SRF spread across the units of Wood Anatomy & Wood Properties. Difficulty: 1 easy, 12 medium, 25 hard.
| Mechanical properties: bending, compression, hardness | 5 | |
| Hardwood structure: vessels, fibres, parenchyma; ring-porous and diffuse-porous | 4 | |
| Cell wall structure and chemical composition | 4 | |
| Wood-water relations: moisture content, fibre saturation point, shrinkage | 4 | |
| Formation of wood: cambium, sapwood and heartwood | 3 | |
| Softwood structure: tracheids, rays, resin canals | 3 | |
| Macroscopic and microscopic identification of timbers | 3 | |
| Wood density and specific gravity | 3 | |
| Natural defects and reaction wood | 3 | |
| Timber grading and the uses of important timbers | 3 | |
| Natural durability of timbers | 3 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Why is sapwood of all species non-durable?
C. It lacks extractives and holds starch and sugars
Without protective extractives and with stored food, sapwood attracts fungi and insects.
Cross-field pits in softwoods connect:
C. Ray parenchyma to axial tracheids
Their shapes (window-like, pinoid, piceoid, cupressoid, taxodioid) aid identification.
Deodar (Cedrus deodara) normally:
B. Lacks normal resin canals but can form traumatic ones
Cedars form traumatic canals in tangential rows after injury.
Fine ripple marks on tangential surfaces of Dalbergia and Pterocarpus result from:
A. Storied structure of rays and other elements
Elements arranged in horizontal tiers produce ripple marks.
A wood has total tangential shrinkage of 8% and FSP of 28%. Assuming linear shrinkage below FSP, what tangential shrinkage occurs on drying to 12% MC?
B. 4.6%
8 × (28 − 12)/28 = 4.6%. 3.4% uses 12/28 instead of (28 − 12)/28; 8% is shrinkage to oven-dry.
A quarter-sawn board shrinks less in width than a flat-sawn board because its width is:
A. Radial
Radial shrinkage is about half tangential.
A 20 × 20 mm clear specimen on a 300 mm span fails at a centre load of 2000 N. Using MOR = 3PL/(2bd²), what is its modulus of rupture?
B. 112.5 N/mm²
MOR = 3 × 2000 × 300/(2 × 20 × 400) = 112.5 N/mm². Omitting the 3 gives 75; omitting the 2 in the denominator gives 225.
Interlocked grain, common in dipterocarps and some eucalypts, causes:
C. Tearing in planing but attractive ribbon figure
Alternating spiral direction resists splitting and gives ribbon figure on quarter-sawn faces.
Brittleheart in large tropical logs is caused by:
C. Long-term compressive growth stress near the centre
The central wood fails in compression over decades.
Fast-grown plantation teak may differ from natural teak in that its heartwood can be:
D. Less durable
Durability varies with growth conditions and tree age.
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