Answer:
lichens are not purely mutualistic relationships.
Explanation:
An organism is said to mutualistic relationship when two organisms which are of different species "work together," each benefiting from the relationship.
A mutualistic relationship entails that each organism needs the other in one way or the other to survive.
This mutual relationship in some occassions happen because of coexistence within a place or sharing of an ecosystem.
An example of mutualistic relationship is that of The bee and the flower. Bees fly from one flower to another gathering nectar, which they make into food, benefiting the bees. When they land in a flower, the bees get some pollen on their hairy bodies, and when they land in the next flower, some of the pollen from the first one rubs off, this leads to pollinating for the plant. This benefits the plants. In this mutualistic relationship, the bees get to eat, and the flowering plants get to reproduce.
If haustoria from the fungal partner were to appear within the photosynthetic partner of a lichen, and if the growth rate of the photosynthetic partner consequently slowed substantially, then this would support the claim that lichens are not purely mutualistic relationships.
