Describe lichen morphology, specifying the location of the fungus and the photosynthetic symbiont. What are some of the neat uses of lichens by humans?

Question

What will be an ideal response?

Answer 1

Lichen are composed of a fungus (mycobiont) and a photobiont (algae, cyanobacteria, or both). The alga or bacterium provides photosynthetic nutrition, while the fungus provides minerals and protection (from UV light damage). The mycobiont makes up the body of the lichen. The photobiont cells are typically present towards the upper surface where light levels are highest. The mycobiont is present throughout the lichen, and anchors the lichen to solid surfaces. New tissues produced by a lichen that has been turned upside will orient in the regular position. This suggests the fungus can sense light and readjust to enable the photobiont to receive adequate illumination.

Cortex of a lichen is a dense, protective skin of fungal tissue. The fungus actually surrounds each of the photobionts with hyphae. It uses specialized structures called haustoria to penetrate the photobiont cell. Through the haustoria, fungi extract the sugars produced by photosynthesis and the nitrogen from n-fixation. The third layer is the medulla, which is largely made up of fungal cells. Another layer, the lower cortex, is where the lichen is attached to the substrate by hair-like strands. The entire structure of any lichen is known as a lichen body, or thallus.

In the Russian Far East, Usnea filipendula ("beard lichen") was used as a powder to treat wounds. When it was tested for antibacterial activity, the results were quite positive.
"Wolf lichen" (Letharia vulpina) was the most widely used dye lichen for native peoples in North America. "Oakmoss lichen" is an important ingredient in fine perfumes. It is harvested commercially in large quantities in south-central Europe.