Within Lichens, Fungal Hyphae Tightly Press Against Their Photosynthetic Symbiont

Multiple Choice

Within lichens, fungal hyphae tightly press against their photosynthetic symbiont, sometimes breaching the cell wall to invade these cells and encourage the "leak" of photosynthetic products.Despite the effect fungi have on their photosynthetic counterparts, what evidence supports the claim that lichens are an example of mutualism?

A) Some fungi involved in these associations can grow independently of their photosynthetic partners.
B) The fungal component protects the photosynthetic counterpart from accumulating too much sugar from photosynthesis.
C) In many places where lichens grow, the photosynthetic counterparts would be unable to survive without the fungal association.
D) The fungal component provides the photosynthetic cells with carbon, while the photosynthetic cells process this carbon into sugar for the fungus.
E) Genome sequencing of these photosynthetic counterparts shows key metabolic genes are missing, suggesting a dependence on the fungus to provide these metabolites.