ICAR AIEEA-PG — Forestry/Agroforestry & Silviculture (Major Subject Group 09) · India · National Testing Agency for ICAR
Original practice questions written to the published syllabus · not past papersHow trees grow, take up water and nutrients, fix carbon, allocate it to wood, roots and reproduction, and respond to drought, heat, cold and shade.
In the exams: ICAR AICE-JRF 59 Unit 3 (growth substances) and Unit 12 (enhanced CO2); ICAR AIEEA-PG Group 09 Unit I plant physiology basics
How our questions for ICAR AIEEA-PG spread across the units of Tree Physiology. Difficulty: 20 easy, 44 medium, 2 hard.
| Mineral nutrition and mycorrhizae | 7 | |
| Shoot and root growth patterns: determinate and indeterminate growth | 7 | |
| Dormancy, phenology and cold hardiness | 7 | |
| Stress physiology: drought, salinity, flooding, frost | 7 | |
| Cambial activity, wood formation and growth rings | 6 | |
| Plant growth regulators and their role in propagation | 6 | |
| Reproductive physiology: flowering, pollination, seed development | 6 | |
| Water relations: transpiration, cohesion-tension, xylem embolism | 5 | |
| Photosynthesis in trees: C3 pathway, light response, shade tolerance | 5 | |
| Respiration and carbon allocation | 5 | |
| Elevated CO2 and temperature effects on tree growth | 5 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
P50 in a xylem vulnerability curve is:
C. The water potential at which 50% of conductivity is lost
P50 summarises embolism resistance; more negative P50 means more resistant xylem.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
Which group consists of shade-intolerant (light-demanding) species?
B. Pines, larches, birches and poplars
Pioneer genera such as pines, larches, birches and poplars demand light; firs, hemlocks, beeches, yews and sugar maple are classically shade-tolerant.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
Green leaves contain 2.0% N and freshly fallen leaves 0.9% N (on a comparable basis). What is the N resorption efficiency?
D. 55%
(2.0 − 0.9)/2.0 × 100 = 55%. 45% is the fraction remaining in litter; 1.1 is the difference in percentage points.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
Distinct annual growth rings in tropical trees form mainly where:
C. A marked dry season or annual flood occurs
In the tropics cambial dormancy is induced mainly by water deficit or flooding; aseasonal humid climates often give indistinct rings.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
Fast-grown short-rotation conifer plantations often yield timber with lower density and more warp because they contain a high proportion of:
D. Juvenile wood
Juvenile wood near the pith has shorter cells, lower density and higher microfibril angle; tension wood occurs in angiosperms.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
In determinate (preformed) shoot growth, the leaves of next year's shoot are:
A. Formed in the bud during the previous season
Preformed shoots expand in one spring flush; indeterminate shoots continue to form leaves during the season.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
Growth inhibition of a bud that cannot be overcome by favourable conditions until a chilling requirement is met is called:
C. Endodormancy
Lang's endodormancy is internal to the bud; ecodormancy (quiescence) is imposed by environment; paradormancy by other organs.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
Flooding injures roots of intolerant trees mainly because:
C. Waterlogged soil quickly runs out of oxygen
Oxygen diffuses about ten thousand times more slowly in water than in air; roots switch to inefficient anaerobic respiration.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
Tree-ring studies worldwide show a rise in intrinsic water-use efficiency with rising CO₂. What have they generally found for growth?
B. Little matching growth gain
Higher iWUE has often not translated into faster growth, suggesting nutrients, drought or warming limit responses.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
Atmospheric CO₂ was about 280 ppm before industrialisation. Roughly what level had it reached by the mid-2020s?
D. Over 420 ppm
Global mean concentration passed 420 ppm in the early 2020s.
Further reading: See the manual sources: Pallardy, Physiology of Woody Plants; Tyree and Zimmermann; Lambers et al.; Smith and Read; Hartmann and Kester
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