Q56 - Rubber Tree Stem Diameter Dynamics
Rubber trees (Hevea brasiliensis) are tapped for latex, a commercially valuable product. Continuous monitoring of trunk diameter reveals daily fluctuations and long-term growth patterns.
The data show trunk diameter variations measured over several days in tapped and untapped rubber trees. Daily cycles of stem contraction and expansion are superimposed on a long-term growth trend.
True or false?
Q56.1. Daily stem diameter variations show a consistent pattern of nighttime increment and daytime contraction.
Q56.2. The daily variations in stem diameter are related to water status of the xylem.
Q56.3. The daily variations in stem diameter are driven by changes in phloem pressure.
Q56.4. Latex tapping (harvesting) reduces overall trunk growth increment.
Q56.5. The latex harvesting creates a competing sink that diverts resources from trunk growth.
Question reproduced from IBO 2023, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF