Q55 - Extrafloral Nectaries and Herbivory Defense
Extrafloral nectaries (EFNs) are nectar-secreting glands located outside of flowers. They attract ants and other predatory insects that defend the plant against herbivores. This is an example of biotic defense.
Plants can also invest in mechanical defense, such as tough leaves with low specific leaf area (SLA). Low SLA indicates thicker, more structurally reinforced leaves.
The figures show data comparing herbivory levels, SLA, and other traits between species with and without EFNs in a tropical community.
True or false?
Q55.1. Plants with extrafloral nectaries (EFNs) suffered less herbivory than plants without EFNs.
Q55.2. Both H. umbellata and B. campestris invest in EFNs.
Q55.3. All plants without EFNs had significantly lower SLA (specific leaf area) than plants with EFNs.
Q55.4. Plants without EFNs had significantly greater herbivory levels regardless of their SLA values.
Q55.5. Biotic defense (via EFNs) reduced herbivory by more than 50% compared to mechanical defense alone.
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