Q95 - Slug, Earthworm, and Vegetation-Type Effects on Forest Seedling Survival

Theoretical B Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

To understand the effects of several factors on plants (Agrimonia rostellata and Trillium erectum) in forest ecosystems, students transplanted seedlings into experimental sites and observed the proportion of surviving seedlings growing with native or non-native vegetation, with or without slugs, and with low or high earthworm density. The results are shown in the figure below.

Figure Q.95 Proportion of surviving seedlings, for Agrimonia rostellata (panels A, B) and Trillium erectum (panels C, D), each shown with and without slugs present, crossed with native vs. non-native vegetation and low vs. high earthworm density.

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

A. Slug exclusion has a positive effect on the survival of Agrimonia rostellata and Trillium erectum in high earthworm density.

B. Slug effects are dependent on other stressors, especially on interactions with non-native plants and earthworms.

C. Earthworms have positive effects on Agrimonia rostellata and Trillium erectum.

D. Non-native plants and slugs synergistically decrease seedling survival through increased competition and consumption.

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Question reproduced from IBO 2016, Theoretical Paper B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)