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Q43 - Non-Lethal Predation Effects on Dragonfly Larval Survival and Metamorphosis

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

A population of dragonfly larvae (Leucorrhinia intacta) is separated into two groups. In both groups, larvae populations are put inside a cage with no food limitation. The first group is exposed to a fish predator that can swim freely, but cannot enter the cage. The second group is a control with no fish. The proportion of larvae surviving to metamorphosis and the proportion of live larvae failing to complete emergence in the two groups are shown in Figure Q.43.

Figure 1. Figure 1.

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

A. One of the causes of high failure rate of metamorphosis of the larvae upon exposure to a non-lethal predator is cannibalism.
B. The high mortality of larvae in the first group is due to predator-induced stress.
C. In the predator treatment, the percentage of individuals that survived the larval stage completed emergence to the adult stage is lower than the percentage of those in the fishless treatment.
D. The survival of dragonfly before metamorphosis is dependent on the predator while those during metamorphosis is not.
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Question reproduced from IBO 2016, Theoretical Paper A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)